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HP 6104A User's Manual

1. di eas pi sla ace ig da de 2 2 3 OPERATING INSTRUCTIONS 6 6 0 wt we o 3 1 3 1 Turn On Checkout Procedures eee ese ees 3 1 3 3 Operating Modes saasa sorora soo 2 Be ese a 3 2 23 5 Normal Operating Mode 2 an eas a a e ae 3 2 3 8 Constant Voltage s s eas 68 Go ae Wo Se OL A do 3 2 3 10 Constant Currents s s e s s ee sos ses AA le 3 3 3 12 Overvoltage Crowbar Operation rosoe soseo 3 3 3 17 Connecting Load s s e s eo e as e Aa aa aca ds e ee 3 4 3 21 Operation Beyond Normal Rated Output soea os ee 3 4 3 23 Remote Programming Constant Voltage sees 3 4 3 29 Remote Programming Constant Current 325 3 36 Remote Sensing Figure 3 7 c 3 6 3 41 Series Operation s ees e e RA A ck ta 3 7 3 43 Auto Series Operation Figure 3 9 eens 3 7 3 47 Parallel Operation ee ee ee ew we we tt te e 3 8 3 49 Auto Parallel Operation Figure 3 11 ae 3 8 3 52 Auto Tracking Operation Figure 3 12 3 9 3 55 Special Operating Considerations lt 2 eee 3 9 3 56 Pulse Loading Ca ie eae ee oe ee 3 9 3 58 Output Capacitance se 3 9 3 61 Reverse Voltage Loading s ew ep we we 3 10 3 63 Reverse Current Loading s s so soaa s ee eee evens 3 10 3 65 Gross Current Limit Automatic Dual Range Switching
2. 3 10 ii SECTION GENERAL INFORMATION 1 1 DESCRIPTION 1 2 This instruction manual contains operating and service instructions for four Hewlett Packard precision power supplies The four models desig nated 6104A 61054A 6114A and 6115A are ideal for applications requiring an accurate highly stable and easily settable source of dc voltage or current All models are completely solid state and feature constant voltage constant current operation auto matic dual range operation overvoltage crowbar protection front panel voltage and current meter ing and provisions for remote voltage and current programming In addition all models are capable of auto series auto parallel and auto tracking operation Front panel mounted controls allow current limit and overvoltage trip points to be con veniently set while OVERVOLTAGE and CURRENT MODE light emitting diodes indicate when the cor responding condition is in effect 1 3 Additional features and characteristics appli cable to specific models are described in the fol lowing paragraphs Section III of this manual cov ers the use of all controls and indicators and gives procedures for implementing the various operating modes 1 4 MODELS 6104A and 6105A 1 5 These models employ individual voltage and current meters and a 10 tum potentiometer for setting output voltage levels With the exception of some component values and meter scale mark ings the two models are phys
3. 3 61 REVERSE VOLTAGE LOADING 3 62 A diode CR15 is connected across the output terminals Under normal operating conditions the diode is reverse biased anode connected to the negative terminal If a reverse voltage is applied to the output terminals positive voltage applied to the negative terminal the diode will conduct shunting current across the output terminals and limiting the voltage applied across the output ter minals to the forward voltage drop of the diode This diode protects the series transistors and the output electrolytic capacitors 3 63 REVERSE CURRENT LOADING 3 64 Active loads connected to the power supply may actually deliver a reverse current to the power supply during a portion of its operating cycle An external source cannot be allowed to pump current into the supply without loss of regulation and pos sible damage to the output capacitor To avoia these effects it is necessary to preload the sup ply with a dummy load resistor so that the power supply delivers current through the entire opera tion cycle of the load device 3 65 GROSS CURRENT LIMIT AUTOMATIC DUAL RANGE SWITCHING 3 66 The power supply can be operated at a CUR RENT setting above the high range VOLTAGE rating as given below 6104A 6114A 0 20V 0 2 0A 20 40V 0 1 0A 6105A 5115A 0 50V 0 0 8A 50 100Vi0 0 4A For instance the 6104A can be operated with the CURRENT control set to 1 5A and the VOLTAGE con trol set to 30V
4. 4 15 VOLTAGE FEEDBACK LOOP 4 16 The voltage feedback loop functions to main tain the output voltage of the supply constant Por purposes of this discussion assume that the out put voltage instantaneously rises goes positive due to a change in the external load circuit The change may be in the form of a slow rise in the out put voltage or a positive going ac signal The slow voltage change is coupled to summing point Al through the VOLTAGE control either the ten turn potentiometer for Models 6104A and 6105A or the pushbutton assembly for Models 6114A and 61154 The ac signal is coupled to Al through capacitor Cl 4 17 The rise in output voltage causes the voltage at terminal Al and thus pin 3 of the constant volt age comparator to decrease the S potential rises goes positive so that S is more negative with re spect to S therefore the input to the voltage comparator goes negative This input pin 3 of the constant voltage comparator is the non invert ing input so that the comparator s output voltage also decreases This negative going error voltage is coupled through OR gate diode A2CR2 amplified by pre driver A1Q1 and then fed to the series reg ulator via driver Q4 located on the rear heat sink The negative going input to the series regulator causes the series transistors to decrease their con duction so that they drop more of the raw dc input voltage thus reducing the output voltage to the original pre dist
5. ied by a three part serial number The first part is the power supply model number The second part is the serial number prefix consisting of a number letter combination denoting the date of a significant design change and the country of man ufacture The first two digits indicate the year 12 1972 13 1973 20 1980 etc the sec ond two digits indicate the week 01 through 52 and the letter A G J or U designates the U S A West Germany Japan or the United Kingdom respectively as the country of manufac ture The third part is the power supply serial number a different 5 digit sequential number is assigned to each power supply starting with 00101 1 24 If the serial number prefix on your unit does not agree with the prefix on the title page of this manual change sheets supplied with the manual or manual backdating changes in Appendix A define the differences between your instrument and the instrument described by this manual 1 25 ORDERING ADDITIONAL MANUALS 1 26 One manual is shipped with each instrument Additional manuals may be purchased from your local Hewlett Packard field office see list at rear of this manual for addresses Specify the model number serial number prefix and HP part number shown on the title page SECTION Il INSTALLATION 2 1 INITIAL INSPECTION 2 2 Before shipment this instrument was in spected and found to be free of mechanical and electrical defects As soon as the inst
6. 1 when the volt age and current settings are within the normal lim its for both two output ranges and therefore the comparators have complete control of the series regulator and 2 when the voltage setting is at the high range and the current setting is also set at a high value in which case the gross current limit circuit activates if the high voltage range cur rent rating half of the low voltage range current rating is exceeded The 6105A 6115A series reg ulator circuit operates in the same way except that voltage levels are highef and output current less 4 39 The power supply utilizes dual full wave rectifier filters to obtain two raw de supply volt 4 6 ages which are represented as two independent sources in Figure 4 4 a simplified schematic of the series regulator circuit Switching between the sources is accomplished by diodes CR11 and CR12 In order to best understand the action of these diodes the circuit will be analyzed for two separate in range conditions high and low out put voltage after which it will be discussed from the point of view of an out of range condition i e the voltage and current controls are both set to high rating To simplify the discussion assume that the diode voltage drops and the transistor base emitter junction voltages are all 1V when forward biased Similarly assume that the voltage across zener diodes VR3 and VR4 is 6 5V total EN a DRIVE SIGNAL de Figure 4
7. the output will be the desired output voltage NOTE The output voltage can be set above the recommended ranges but the crowbar trip voltage may not be adjustable above the recommended ranges d Slowly turn the OVERVOLTAGE control counterclockwise until the crowbar trips output falls towards 0 volt and OVERVOLTAGE indicator comes on e The crowbar remains activated and the output shorted until the supply is turned off To reset the crowbar turn the supply off If neces sary before turning the supply back on remove the external resistor installed in step c and re place the voltage programming pushbutton switch assembly connections to the Al board Next set output voltage to zero Turn supply back on and set it to desired output voltage see next paragraph for an important operating consideration 3 14 False crowbar tripping must be considered when adjusting the trip point If the trip voltage is set too close to the operating output voltage a transient in the output or load can falsely trip the crowbar It is recommended that the crowbar trip voltage be set higher than the operating output voltage by 2 0 5V For example the crowbar should be set to trip at a minimum of 31 1Vdc if the output voltage is set to 30Vdc This operating margin of course is not possible if the crowbar is set to trip at or near its lower limit 3 15 Resetting Crowbar If the crowbart ing normal operation supply output goes to
8. A Ee A E INPUT POWER 104 127 Vac 48 440Hz 150VA maximum Standard 208 254 Vac 48 440Hz 150VA maximum Switch Selected DC OUTPUT Single output dual range with automatic cross over between ranges Models 6104A amp 6114A 0 20V 2A 20 40V 1A Models 6105A amp 6115A 0 50V 0 8A 50 100V 0 4A METERS Models 6104A and 61052 current meters with 2 full scale accuracy Models 6114A and 6115A Single dual function voltage and current meter with 2 full scale accuracy TEMPERATURE RATINGS Operating 0 to 55 C Storage 40 to 750C COOLING Convection cooling is employed The supplies have no moving parts DIMENSIONS See outline diagram Figure 2 1 WEIGHT 17 lbs 7 7kg net 21 lbs 9 5kg shipping II ieOitArrtrenpRiise CONSTANT VOLTAGE OUTPUT A a a LOAD REGULATION For load current change equal to current rating of supply measured at rear terminals Models 6104A amp 6114A 0 0005 1004V Models 6105A amp 6115A 0 0005 50uV LINE REGULATION i Fora 10 change in line voltage from nominal value 115 Vac or 230 Vac Models 6104A amp 6114A 0 0005 40uV Models 6105A amp 6115A 0 0005 100pV RIPPLE AND NOISE 40yVrms 100uV p p up to 20MHz at any line Individual voltage and voltage and under any load condition within rating 1 2 Specifications Models 6104A 61054A 6114A 6115A TEMPERATURE COEFFICIENT Output voltage change per degree Centigrade c
9. However as shown in Figure 3 13 if the load resistance draws output current above the high range rating i e greater than 1A for the 6104A 6114A or 0 4A for the 6105A 6115A the power supply enters the gross current limit region the CURRENT MODE indicator comes on In the gross current limit region output current is maintained up to approximately 130 at nominal line voltage of the high range rating 1 3A for the 6104A 6114A or 0 52A for the 6105A 6115A of the supply while output voltage is maintained at the VOLTAGE setting up to the maximum high range rating If load resistance continues to change and causes output current to exceed the gross cur rent limit region however the supply is automati cally switched to the low range and output voltage is reduced to approximately 130 again at nomin al line voltage of the low range rating 26V for the 6104A 6114A or 65V for the 6105A 6115A Of course at this point the VOLTAGE setting of the supply is overridden Purther load reductions cause the supply to enter the constant current mode and output voltage is further reduced as necessary to supply the necessary output current depending upon load requirements and the CURRENT setting Notice that when operated in the gross current limit region the supply s output is uncalibrated and may not meet certain specifications ripple etc Note further that if the supply is operated at low or high line the gross current
10. Indicators 3 1 TURN ON CHECKOUT PROCEDURES c Set LINE switch 6 to ON and observe that indicator lights 3 2 The following checkout procedure describes d Adjust VOLTAGE control through the the use of the front panel controls and indicators entire output voltage range as indicated on meter Figure 3 1 for either the dual meter ten turn Adjust output for desired operating voltage VOLTAGE control supplies the 6104A or 61054A or the single meter pushbutton VOLTAGE control NOTE supplies the 6114A or 6115A The checkout pro cedures ensure that the power supply is operation To increase the 6114A 6115A output vol al tage depress the pushbutton switch a a For the 6114A 6115A set meter switch bove the associated digit To decrease O to VOLTS there is no meter switch on the the voltage depress the pushbutton 6104A or 61054 switch below the associated digit Fine b Rotate OVERVOLTAGE crowbar control output voltage adjustment is provided by D screwdriver adjust fully clockwise and ro the millivolt digit thumbwheel potentio tate CURRENT control G to middle of range meter e To ensure that the overvoltage crowbar circuit is operational rotate the OVERVOLTAGE con trol counterclockwise until the supply crowbars Output voltage will fall to approximately one volt and the OVERVOLTAGE and CURRENT MODE indica tors and respectively will light To deactivate the crowbar return the OVERVOLTAGE control to maxi
11. components is diode A1CR15 Connected across the output terminals of the supply the diode prevents internal damage from reverse voltages that might be applied across the supply This could occur for example during Auto Series operation if one supply was turned on before the other 4 63 Diodes CR23 and CR24 limit the output of the supply if the connections between both output ter minals and the sensing terminals S are inadver tently removed Diode CR14 previously mentioned in the driver amplifier description protects the driver stage from damage due to same polarity voltages that might be applied to the supply in such applications as battery charging and discharging SECTION V MAINTENANCE 5 1 INTRODUCTION 5 2 Upon receipt af the power supply the per formance check Paragraph 5 5 should be made This check is suitable for incoming inspection If a fault is detected in the power supply while mak ing the performance check or during normal opera tion proceed to the troubleshooting procedures Paragraph 5 53 After repair and replacement Paragraph 5 70 perform any necessary adjust ments and calibrations Paragraph 5 83 Before retuming the power supply to normal operation Table 5 1 REQUIRED CHARACTERISTICS Differential Voltmeter Oscilloscope DC Voltmeter AC Voltmeter Oscillator Amplifier Sensitivity 500uV full s ale min input impedance 100Mna min Sensiti
12. e Al AZ AS A4 A5 AG AT A8 8 S AIZAI4 SLAVE MASTER A8 S S AIS Al4 pea AI A2 A3 A4 AS AG AT eialelelelale vr aw al ERRE RAIS SLAVENO ARRE SLAVE NO 2 Al A2 A3 A4 AS AG A AJ A2 A3 A4 A5 AG AT e ojete le A Figure 3 11 Auto Parallel Operation Two Units and Three Units slave supply In addition the strapping pattern of the added slave should be the same as slave 1 Remote sensing and programming can be used though the strapping arrangements shown in Figure 3 11 show local sensing and programming In or der to maintain the temperature coefficient and stability specifications of the power supply the external resistors Ry should be stable low noise low temperature coefficient less than 5ppm per degree Centigrade resistors The power rating of Ry should be at least 10 times the actual power dissipated in the resistor 3 52 AUTO TRACKING OPERATION Figure 3 12 3 53 The Auto Tracking configuration is used when several different voltages referred to a com mon bus must vary in proportion to the setting of a particular instrument the control or master A fraction of the master s output voltage is fed to the comparison amplifier of the slave supply thus controlling the slave s output The master must have the largest output voltage of any power sup ply in the group It must be the most positive supply in the example shown in Figure 3 12 3 54 The output volta
13. in the output voltage until the output current reaches Ig a value equal to the front panel current control set ting At this point the supply automatically changes its mode of operation and becomes a constant cur rent source still further decreases in the value of load resistance are accompanied by a drop in the supply output voltage with no accompanying change in the output current value With a short circuit across the output load terminals Ioyr Is and EOUT 0 CONSTANT VOLTAGE OPERATING REGION c CONSTANT CURRENT OPERATING REGION SHORT CIRCUIT LOAD Es FRONT PANEL VOLTAGE CONTROL SETTING Tg FRONT PANEL CURRENT CONTROL SETTING _ s CRITICAL OR CROSSOVER VALUE C Ig OF LOAD RESISTOR Figure 4 2 Operating Locus of a CV CC Supply Operated Within Range Ratings 4 7 Thus at VOLTAGE and CURRENT settings within the two normal ranges the crossover val ue of load resistance can be defined as Ro Eg Is Adjustment of the front panel VOLTAGE and CURRENT controls permits this crossover resistance Ro to be set to any desired value from 0 to If Riis greater than Rc the supply is in constant voltage operation while if Ry is less than Rc the supply is in constant current operation 4 8 Figure 4 3 shows the output characteristics of the supply when it is operated at an output cur rent setting above the high voltage range rating assume the CURRENT control Ig and VOLTAGE control Eg are set at the
14. it to driver transistor Q4 Dri ver Q4 controls the conduction of the series regu lator by controlling the mount of drive current diverted away from the regulator As Q4 increases its conduction more drive current flowing from the 7 5V bias source through R33 is diverted from the bases of Q2 and Q3 causing a decrease in their conduction and a corresponding decrease in the output voltage 4 35 Driver transistor Q4 performs an additional function that of discharging the output capacitor during rapid down programming When the supply is rapidly down programmed diode CR13 conducts a current path is thus established from the positive of output capacitor A1C12 through Q4 and back to the negative of the capacitor thru R25 AlR14 in series with CR13 and CR14 limits the current that can flow through this path Triple junction diode CR14 protects Q4 from reverse voltages that could be developed across it in situations such as Auto Series operation when one supply is turned on be fore the other In addition CR14 aiso maintains the emitter of Ql and the base of 04 at a constant potential thus limiting the power dissipated in 04 under conditions where an external same polarity voltage is applied to the output terminals of the supply such as battery charging discharging 4 36 SERIES REGULATOR 4 37 The series regulator consists of transistors Q1 through Q3 mounted along with driver Q4 on the heat sink which serve as the ser
15. limit region will vary decrease at low line and increase at high Line 130 OF MAX HI YS RANGE CURRENT MAX HI RANGE RATING GROSS CURRENT LIMIT REGION 4 OUTPUT UNCALIBRATED Es t s130 OF MAX 1 2Emax LOW RANGE LORANGE AS J VOLTAGE 4m LOW RANGE EQut PA VOLTAGE CURRENT LIMITS V2 IMAX HIGH RANGE HI RANGE VOLTAGE CURRENT LIMITS Gross Current Limit Dual Range Switching Figure 3 13 SECT ON IV i PRINCIPLES OF OPERATION 28V UNREG 16V 14 7V XS REFERENCE SUPPLY RECTIFIER AND SERIES REGULATOR RECTIFIER DRIVER NOTE HA CONSTANT CURRENT COMPARATOR CONTROL RIS CURRENT SAMPLING RESISTOR CONSTANT VOLTAGE COMPARATOR OVER VOLTAGE PROTECTION CROWBAR METER CIRCUIT CONTROLS min DENOTES CONSTANT VOLTAGE FEEDBACK PATH e en ENOTES CONSTANT CURRENT FEEDBACK PATH Figure 4 1 4 1 OVERALL BLOCK DIAGRAM DISCUSSION 4 2 The major circuits of the power supply are shown on the overall block diagram Figure 4 1 The ac line voltage is first applied to the power transformer after which it is rectified and filtered The resulting raw dc is then fed to the series reg ulator which varies its conduction to obtain the proper output voltage or current The series regu lator includes a current limit circuit that automati cally places the supply in the low voltage range depending upon the output voltage and current set tings t
16. maximum rating of the supply As can be seen up to the maximum high voltage range current rating the supply operates as a constant voltage source furnishing the high range output voltage as specified by the setting of the VOLTAGE control As load resistance decreases and output current reaches the maximum high volt age range current rating point A the supply goes into the gross current limit region in which the out put current is maintained up to approximately 130 at nominal line voltage of the high voltage range current rating If the load resistance continues to decrease and attempts to draw more current the output current will increase slightly while the out put voltage decreases rapidly since the gross cur rent limit circuit supplies a near constant current output a decrease in load resistance results in a decrease in output voltage When the output volt age reaches a point approximately 130 again at nominal line of the low voltage range rating point B the gross current limit circuit turns off and the output current increases up to the programmed val ue Atthis point the supply enters the constant current mode in which as described above the output voltage is varied to maintain the output cur rent at the setting of the CURRENT control Notice then that under these circumstances the VOLTAGE control of the supply is overriden by the gross cur rent limit circuit and the supply is automatically switched to the lo
17. models 6114A 6115A and a differential amplifier stage A2U2 and associated components An integrated circuit is used for the differential amplifier in order to mini mize differential voltages due to mismatched trans istors and thermal differentials 4 22 The constant voltage comparator continuous ly compares the voltage drop across the VOLTAGE con trol with the output voltage and if a difference exists produces an error voltage whose amplitude is proportional to this difference The error signal ultimately alters the conduction of the series reg ulator which in turn alters the output current so that the output voltage becomes equal to the volt age drop across the VOLTAGE control Hence through feedback action the difference between the two inputs to A2U2 is held at zero volts 4 23 One input of the differential amplifier pin 2 is connected to the output voltage sensing terminal of the supply S through matching resistor R16 Potentiometer R13 provides a variable input bias that allows the output voltage of the supply to be adjusted to exactly zero when the supply is pro grammed for zero output The other input of the differential amplifier pin 3 is connected to a sum ming point TB1 Al at the junction of the program ming resistors and the current pullout resistor A2R24 Instantaneous changes in the output volt age at the summing point due to manipulation of the VOLTAGE control or changes in the external load circui
18. nor the aver Gye 3 9 MASTER AB Ala Al A2 A3 A4 AS AG AT RABIA E A lA But AB S S Al Al4 SLAVE To ejeje ajo jejo Al AZ A3 A4 AS AG AT MASTER AL A2 A3 A4 AS AG AT ALP O AO had a a ata a aoe SLAVE NO A por ala Pr ejeje eR lelie Al AZ AB AG AS AG AT A8 5 S AI3 Al4 A2 A3 A4 AS AG AT Ai 212l2lelg gl AS A8 AROS SR AG LJ SLAVE NO 2 Figure 3 12 Auto Tracking Operation Two and Three Units 3 58 OUTPUT CAPACITANCE 3 59 An internal capacitor C12 connected across the output terminals of the power supply helps to supply high current pulses of short duration during constant voltage operation To reduce current surges this capacitor can be removed by unstrap ping terminal A7 Any capacitance added external ly will improve the pulse current capability but will decrease the safety provided by the constant current circuit A high current pulse may damage load components before the average regulator cur rent is large enough to cause the constant current circuit to operate 3 60 The effects of the output capacitor during constant Current operation are as follows a The output impedance of the power sup ply decreases with increasing frequency b The recovery time of the output voltage is longer for load resistance changes c A large surge current causing a high pow er dissipation in the load occurs when the load re sistance is reduced rapidly
19. number full serial number and service required or a brief description of the trouble 2 9 INSTALLATION DATA 2 10 The instrument is shipped ready for bench operation It is necessary only to connect the in strument to a source of power and it is ready for operation 2 11 LOCATION 2 12 This instrument is convection cooled Suf ficient space should be allotted so that a free flow of cooling air can reach the top and rear of the in strument when it is in operation It should be used in an area where the ambient temperature remains between 0 C and 55 C 2 13 OUTLINE DIAGRAM 2 14 Figure 2 1 illustrates the outline shape and dimensions of Models 6104A 6105A 6114A and 6115A gt F pros ed a SR j Figure 2 1 Outline Diagram 2 15 RACK MOUNTING 2 16 The Model 6104A 6105A 6114A and 61154 power supplies may be rack mounted using either the dual rack adapter kit or the combining case with appropriate cooling kit described in para graph 1 20 The necessary installation instruct ions are provided with the accessories 2 17 INPUT POWER REQUIREMENTS 2 18 Models 6104A 6105A 6114A and 6115A may be operated continuously from either a nominal 120 volt or 240 volt 48 440Hz power source A two position selector switch 4 located within the a c power module on the rear panel selects the power source Before connecting the instrument to the power source check that the selector switch setting match
20. point between the raw dc sources is reached point is at approximately 21V At this point CR12 is cut off and GRLI is forward biased and the regulator reverts to the low voltage range of operation described in paragraph 4 40 The supply then will output the specified current and operate as a constant current source respond ing to the error signal developed by the constant current comparator The voltage setting then is overriden and output voltage will be adjusted be tween 0 and 20V to maintain the output current at the required value Resistor R7 allows the gross current limit region to be calibrated R7 is set at the factory at low line voltage to allow gross cur rent limit at approximately 1 2A for the 6104A and 6114A supplies or at 0 48A for the 6105A and 6115A supplies 4 45 REFERENCE SUPPLY 4 46 The reference supply includes a feedback reg ulator similar to the main supply that provides stable reference voltages referenced to that are used throughout the unit The regulated 16V reference voltage is derived from dc obtained from full wave rectifier AICRI CR2 and filter capacitor A1C1 In addition zener diode A1VR3 provides 14 7V reference voltage that is also used through out the unit Also zener diode VR4 with R26 pro vides a regulated 6 2V for use in the overvoltage crowbar circuit The 14 7V and 6 2V are de rived from dc obtained from full wave rectifier A1CR3 CR4 and filter capacitor A1C2 The 16V
21. with low temperature coefficient and power consumption Under normal operating conditions no overvoltage the output of the comparison amplifier is positive and capacitor C14 is charged positive No trigger signal therefore is received by silicon controlled rectifier SCR CR20 and it is an open circuit hav ing no effect on the normal output voltage 4 53 Potentiometer R3 OVERVOLTAGE has 6 2V with respect to 5 applied across it from the ref erence supply The other input to the comparison amplifier is taken at the junction of voltage divider R29 and R30 which is across the output terminals of the supply and divides the output voltage to a maximum of approximately 6 2V when the supply is set to maximum rated output When the voltage input to pin 3 of the comparison amplifier exceeds is less negative the voltage at pin 2 the output of the amplifier goes negative approximately 0 and capacitor C14 discharges through the primary of transformer Tl A positive trigger pulse then is applied to the gate lead of CR20 and the SCR is turned on placing a virtual short across the output of the supply Potentiometer R3 adjusts the point at which the crowbar will trip by increasing or de creasing the negative reference input to the com parison amplifier and thereby requiring the output voltage to increase or decrease in a negative di rection before it is more negative than the reference input to cause the amplifier output to go
22. 2 A3 A4 AS AG AT Al elolglelgigle WAW Figure 3 9 Auto Series Operation Two and Three Units 3 46 When the center tap of an Auto Series combin ation is grounded coordinated positive and nega tive voltages result This technique is commonly referred to as rubber banding and an external ref erence source may be employed if desired Any change in the internal or external reference source e g drift ripple will cause an equal percentage change in the outputs of both the master and slave supplies This feature can be of considerable use in analogue computer and other applications where the load requires a positive and a negative power supply and is less susceptible to an output voltage change occuring simultaneously in both supplies than to a change in either supply alone 3 47 PARALLEL OPERATION 3 48 Normal Parallel Connections Figure 3 10 Two or more power supplies can be connected in parallel to obtain a total output current greater than that available from one power supply The total output current is the sum of the output currents of the individual power supplies The output CURRENT controls of each power supply can be separately set The output voltage controls of one power sup ply should be set to the desired output voltage the other power supply should be set for a slightly larger output voltage The supply set to the lower output voltage will act as a constant voltage source the supply set to the higher
23. 3 ee gt Power Sing a PS Liked hin a il il PRECISION POWER SUPPLIES MODELS SER 6104A 6114A 6105A 6 OPERATING AND SERVICE MANUAL FOR SERIALS 1209A 00051 AND ABOVE For Serials Above 1209A 00051 a change page may be included HP Part No 5950 5976 Hewlett Packard Printed June 1972 TABLE OF CONTENTS Section Page l GENERAL INFORMATION a ss a 0 a awe a OS ee SS a 1 1 Pel Description e a s a A A A RRA AA A A 1 1 l 4 Models 6104A and 6105A y a ee eoo es 1 1 1 10 Models 6114A and 61154 eee ay er er 1 1 1 16 Specifications s s sess 1 1 1 1 18 Options E Oe eta he Godel Se QO Ar LSS 1 20 Accessories s sash Mee ee OR a OK eS 1 4 l 22 Instrument Identification esas eaa so Ba sos sosoo 1 4 1 25 Ordering Additional Manuals seer ev eevee 1 4 2 INSTALLATION s ecs as a A we eo SS EA Be 4 2 1 2 L Initial Inspection s e s s ae 6 8 ew a Wek Re 2 1 2 3 Mechanical Check lt lt lt 0 0 es a a RS 2 1 2 5 Electrical Check maica ea o 2 1 2 7 Repackaging for Shipment ssas asos sao be Od O 2 1 2 9 Installation Data as sss ee DI Be oe Fee Roe 2 1 end DOCTORA AE AA A Ee A 2 1 2 13 Outline DiagraM ss 2 1 A Rack Mountings A AN 2 1 2 17 Input Power Requirements e ee eae 2 1 2 20 Power Cable a ea Ka
24. 4 Series Regulator Simplified Schematic Models 6104A 6114A 4 40 At a low output voltage point O 5V tran sistors Q2 and Q3 are conducting this requires point to be at 6V Zener diodes VR3 and VR4 thus place the base of O1 point at 12 5V Resistor R8 keeps Q1 conducting at least a certain minimum current at all times thus point 4 is at 11 5V Diode CR12 must be either on or off If it were on point would be at 10 5V Since the anode of CR11 point is always at 30V this condition is not possible so that CR12 must be off Thus CR11 is on point G is at 29V and the 30V raw dc source is supplying the load The power dissipation in Q2 and Q3 is thus approximately 48 watts 24V drop between points f and times 2A load current Notice that under these condi tions with a minimum current through Q1 the drop across R5 is small and the bias across zener diode VR2 is not sufficient for the zener to conduct cur rent the zener is not biased past its breakdown voltage so that the gross current limit circuit has no effect on the operation of the series regulator 4 41 At a high output voltage point 40V transistors Q2 and Q3 are again conducting and point 2 is at 41V Point thus is at 40 5V due to zener diodes VR3 and VR4 Point is at 47 5V because as before Q1 is always conducting at least a certain minimum current Again diode CR12 must either be on or off Since point is at 30V CR12 must be on and
25. 61054 6115A up 60msec no load 150msec no load prog L30msec full load 75msec full load down 600msec no load 1 5sec no load prog i30msec full load 75msec full load Table 1 1 Specifications Models 6104A 61054 6114A 6115A continued OVERVOLTAGE CROWBAR PROTECTION Trip Voltage Range approximate 0 5V to 10 above rated output voltage of supply Margin Minimum 2 0 5V above output volt age to prevent false activation DC OUTPUT ISOLATION Supply may be floated at up to 300V above ground CONSTANT CURRENT OUTPUT LOAD REGULATION 0 01 500A for load voltage change equal to the voltage rating of the supply LINE REGULATION For a 10 change in line voltage from nominal value 115 Vac or 230 Vac Models 6104A amp 6114A 0 005 40pA Models 6105A amp 6115A 0 005 20pA RIPPLE AND NOISE 2004A rms lmA p p at any line voltage and under any load condition within rating TEMPERATURE COEFFICIENT Output change per degree Centigrade change in ambient following 30 minute warm up Models 6104A 6114A 0 02 50uA Models 6105A amp 6115A 0 02 254 A DRIFT Total current drift in output over 8 hour interval under constant line load and ambient following 30 minute warm up Conditions must be held constant during warm up Models 6104A amp 6114A 0 25 7mA Models 6105A amp 6115A 0 25 4mA RESOLUTION Minimum output current change obtainable using front panel current contr
26. CR11 must be off point 6 46 5V Thus the 60V raw de source is supplying the load Notice again that in the high voltage range up to 1 amp supplied by the 60V source so that the voltage drop across R5 is still not great enough to bias VR2 past its breakdown point VR2 then still has no affect on the operation of the series regulator The switch ing point between the two ranges occurs when the voltage at point equals that at point 30V this occurs when the output is approximately 21V 51V for the 6105A and 6115A 4 42 Figure 4 5 illustrates the in range operation of the series regulator from a power dissipation point of view When the output voltage is in the low range between zero and 21 volts for the 6104A and 6114A or 0 51 volts for the 6105A and 61154 transistors 02 and Q3 are controlling the output In this region the power dissipation of Qi is very low approximately 1W since the only current going through it is that flowing through R8 When the output voltage is in the high range between 21 and 40 volts or 51 and 100 most of the regula tor dissipation occurs in transistor Q1 with tran sistors Q2 and Q3 clamped to a low voltage and dissipating approximately 7 5W SERIES REGULATOR POWER DISSIPATION APPROX IMATE y N ees RSET 6104461 ida BIOBA 61ISA VOLTAGE Figure 4 5 Series Regulator Power Dissipation 4 43 The obvidus advantage in this type of regu lator circuit is the saving in power d
27. R20 are connected across the positive and negative ser sing terminals with A1R22 used to calibrate the meter Notice also that when slide switch 32 is in the VOLTS position resistors A1R16 and A1RI9 are connected across the current sampling resistor in order to replace the current measuring circuit that is connected across the current sampling re sistor when the switch is in the AMPS position Thus the effect of the meter circuit on the con stant current performance of the supply will be the same regardless of the position of the meter switch Similarly when measuring current S2 in AMPS pos ition the meter and series resistors A1R16 and AIRI17 are connected across the current sampling resistor with A1R17 used to calibrate the meter Further resistors A1R19 and A1R20 and A1R22 are connected across the positive output terminal and the negative sensing terminal to replace the voltage measuring circuit As described for the dual meter circuit the small voltage drop across resistor R18 compensates for the shunt load of the meter circuit which might because it drains up to 1mA affect constant current operation This volt age drop causes the constant current comparator to increase output current just enough to balance the current supplied to the meter circuit 4 61 ADDITIONAL PROTECTION FEATURES 4 62 The supply contains several special purpose components which protect it in the event of unusual circumstances One of these
28. airs of connecting wires This will minimize mutual coupling effects between loads and will re tain full advantage of the low output impedance of the power supply Each pair of connecting wires should be as short as possible and twisted or shielded to reduce noise pickup If a shielded pair is used connect the shield to ground at the power supply and leave the other end unconnected 3 19 If load considerations require that the output power distribution terminals be remotely located from the power supply then the power supply out put terminals should be connected to the remote distribution terminals via a pair of twisted or shielded wires and each load should be separately connected to the remote distribution terminals For this case remote sensing should be used Refer to paragraph 3 36 3 20 Positive or negative voltages can be obtained from the supply by grounding either one of the out put terminais or one end of the load Always use two leads to connect the load to the supply re 3 4 gardless of where the setup is grounded This will eliminate any possibility of output current return paths through the power source ground The supply can also be operated up to 300Vde above ground if neither output terminal is grounded 3 21 OPERATION BEYOND NORMAL RATED OUTPUT 3 22 The shaded area on the front panel meter face s indicates the amount of output voltage or current that may be available in excess of the nor mal rated output
29. and 14 7V 6 2V reference rectifiers are returned to common point Notice too that the raw dc input to the 16V regulator is 28V nominal which is used unregulated in the CURRENT MODE indicator and overvoltage crowbar circuits 4 47 The 16V regulating circuit consists of ser ies regulating transistor A2Q1 driver A2Q2 and comparison amplifier A2U1 As for the constant voltage and constant current comparators the 16V regulator utilizes an integrated circuit for the com parison amplifier to minimize transistor mismatches and thermal differentials The voltage across zen er diode VRI and resistor R9 and the voltage at the junction of the voltage divider comprised of resis tors R8B R5 R8A and R3 R3 is selected at the factory are compared and any difference is ampli fied by the comparison amplifier The error voltage thus appearing at the output pin 6 of the compari son amplifier is amplified by driver stage A202 and applied to series regulator Q1 in the correct phase and amplitude to maintain the 16V output at a constant level Potentiometer R5 is provided to allow the 16V reference to be precisely calibrated see Section V 4 48 Resistor Ri and diode CR1 provide an initial turn on current path for the base emitter circuit of series regulator Q1 This current flow initiates the series regulator action by turning on Q1 In addition diode CR1 assures the correct operation of the comparison amplifier by establishing th
30. cator will come on and output voltage will drop proportionately to maintain constant current In setting the CURRENT control allowance must be made for high peak cur rent which can cause unwanted cross over refer to paragraph 3 56 As discussed above however if voltage is set too high with respect to current the supply will gross current limit and override the VOLTAGE setting see paragraph 3 65 3 10 CONSTANT CURRENT 3 11 To select a constant current output within the normal range ratings of the supply proceed as follows a Short output terminals and adjust CUR RENT control for desired output current b Open output terminals and adjust VOLT AGE controls for maximum output voltage allowable voltage limit as determined by load conditions and current selected in step a If a load change causes the voltage setting to be exceeded the power supply will automatically crossover to con stant voltage output at the voltage setting and out put current will drop proportionately As discussed above however if voltage is set too high with re spect to current the supply will gross current lim it and override the VOLTAGE setting see paragraph 3 65 In setting the voltage limit allowance must be made for high peak voltages which can cause unwanted crossover refer to paragraph 3 56 3 12 OVERVOLTAGE CROWBAR OPERATION 3 13 Trip Point Adjustment The crowbar trip vol tage can be adjusted using the OVERVOLTAGE screw dri
31. e positive bias of the amplifier at a level that is al ways above by an amount equal to the drop across CRI the output of the comparison amplifier Ca pacitor A2C2 connected across the output of the reference supply removes spikes and stabilizes the reference regulator loop 4 49 BIAS SUPPLY 4 50 Additional 7 5V 3V and 4 3V bias vol tages are derived from de obtained from full wave rectifier AICR5 CR6 and filter capacitor A1C3 along with dropping resistor AIR3 Capacitor A1C10 re moves spixes from the bias supply output voltages The 7 5V bias output is developed across zener diodes AZVR3 and VR4 in the series regulator Zen er diode VR4 in conjunction with the drop across series regulator transistors Q2 and Q3 develops the 3V bias voltage The 4 3V bias voltage is supplied by zener diode A2VR5 Resistor R40 connected across VR5 limits the maximum current through the diode and also reduces overshoot when the supply is turned on or off 4 51 OVERVOLTAGE PROTECTION CROWBAR 4 52 The overvoltage protection crowbar circuit protects the load from high voltage conditions such as might result from the failure of the series regu lator transistors This protection is accomplished by placing a short across the output of the supply thus driving output voltage and current towards 0 The overvoltage protection crowbar circuit utilizes an integrated circuit A1U1 comparison amplifier 4 8 that provides high gain and high speed
32. e and thereby assuring linear voltage program ming capability 4 26 Main output capacitor A1C12 stabilizes the series regulator feedback loop when the normal strapping pattern shown on the schematic is em ployed Note that this capacitor can be removed by unstrapping terminal A8 to avoid output cur rent surges or to increase the programming speed of the supply An additional output capacitor Ci connected across the front output terminals helps maintain a low ac output impedance by compensat ing for the inductive reactance of the main output capacitor at high frequencies Cl also prevents any spikes in the output from reaching the load 4 27 CONSTANT CURRENT COMPARATOR 4 28 While basically similar in operation to the constant voltage comparator the constant current comparator includes a current programming constant current source circuit not employed in the constant voltage comparator This circuit provides a con stant current for the CURRENT programming control and is not utilized in the constant voltage compar ator because the voltage comparator must respond to variations in programming voltage current when remote voltage sensing is employed the variations may be caused by the remote sensing leads As in the constant voltage comparator the constent current comparator employs an integrated circuit A2U3 for the differential amplifier in order to minimize differential voltages due to mismatched transistors and thermal d
33. es the nominal line voltage of the source If required move the switch to the other position Note that the power cable must be re moved the plastic door on the power module must be moved aside the fuse extractor must be pulled outward and the fuse must be removed in order to gain access to the selector switch 2 19 When the instrument leaves the factory the proper fuse is installed for 115 volt operation An envelope containing a fuse for 230 volt opera tion is attached to the instrument Make sure that the correct fuse is installed if the position of the slide switch is changed 2A for 115 volt opera tion and 1A for 230 volt operation 2 2 2 20 POWER CABLE 2 21 To protect operating personnel the National Electrical Manufacturers Association NEMA rec ommends that the instrument panel and cabinet be grounded This instrument is equipped with a three conductor power cable The third conductor is the ground conductor and when the cable is plugged in to an appropriate receptacle the instrument is grounded The offset pin on the power cable s three prong connector is the ground connection 2 22 To preserve the protection feature when oper ating the instrument from a two contact outlet use a three prong to two prong adapter and connect the green lead on the adapter to ground SECTION ill OPERATING INSTRUCTIONS E A younge E 3 8 9 2 F woe DE 6114A 6115A 6104A 6105A Figure 3 1 Operating Controls and
34. ge of the slave Eg is a percentage of the master s output voltage En and is determined by the voltage divider consist ing of Ry and the voltage control of the slave sup ply Rp where Eg Em Rp Rx Rp Remote sensing and programming can be used each sup ply senses at its own load though the strapping patterns given in Figure 3 12 show only local sensing and programming In order to maintain the temperature coefficient and stability specifications of the power supply the external resistors Ry should be stable low noise low temperature co efficient less than 5ppm 9C resistors The value of Ry is found by multiplying the voltage programming coefficient of the slave supply by the desired difference between the master supply volt age and the slave supply voltage 3 55 SPECIAL OPERATING CONSIDERATIONS 3 56 PULSE LOADING 3 57 When operated within either of the two range ratings the power supply will automatically cross over from constant voltage to constant current op eration or the reverse in response to an increase over the preset limit in the output current or voit age respectively Although the preset limit may be set higher than the average output current or voltage high peak currents or voltages as occur in pulse loading may exceed the preset limit and cause crossoverto occur If this crossover limit ing is not desired set the preset limit for the peak y thao sarve arata var b a A LOY ement ani
35. hange in ambient following 30 minute warm up Model 6104A 0 005 25uV Model 6105A 0 005 50uV Model 6114A 0 001 15uV Model 6115A 0 001 154V DRIFT Total voltage drift over 8 hour interval under constant line load and ambient following a 30 minute warm up Conditions must be held con stant during warm up Models 6104A 6105A 0 005 50pV Models 6114A 6115A 0 0015 15uV TRANSIENT RECOVERY TIME Less than 50usec is required for output voltage recovery to within 10mV of the nominal output voltage following a change in output current equal to the current rating of the supply OUTPUT IMPEDANCE typical Equivalent to a 05ma resistor in series with a 34H inductor RESOLUTION Minimum output voltage change obtainable using front panel voltage controls Model 6104A 8mV Model 6114A 200uV Model 6105A 16mV Model 6115A 200uV OUTPUT VOLTAGE ACCURACY 0 025 1mV at 23 c 30c at any line vol and load cur within rating after 5 min warm up REMOTE RESISTANCE PROGRAMMING 20005 V 0 01 Programming Coefficient REMOTE VOLTAGE PROGRAMMING Programming Coefficient 1V V Programming Accuracy Accuracy of remote source 0 2mV REMOTE PROGRAMMING SPEED The maximum time required to non repetitively program from 0V to within 99 9 of the maximum rated output voltage up programming or from the maximum rated output voltage to within 0 1 of that voltage above OV down programming 6104A 6114A
36. hat have been selected and the output cur rent of the supply For instance if the supply is set for high voltage output and high current output and the load attempts to draw current above the high voltage range current specification that is above 1A for the 6104A 6114A supplies or above Overali Block Diagram 0 4A for the 6105A 6115A supplies the series regulator limits the output current and then de creases the output voltage to the low range When in the low range the output current is then allowed to reach the CURRENT setting up to the maximum rating of the supply Notice further that dual rectifier filter circuits are employed to provide a low value of raw de voltage to the series regulator in order to minimize internal power consumption during low voltage high current operation Each rectifier filter furnishes most of the raw de voltage to the regulator during one of the two output voltage current ranges of the supply 4 3 The series regulator is part of a feedback loop consisting of the driver and the constant vol tage constant current comparators When operated within the specified ranges during constant voltage operation the constant voltage comparator contin uously compares the output voltage of the supply with the drop across the VOLTAGE control If these voltages are not equal the comparator produces an amplified error signal which is further amplified by the driver and then fed back to the series reg
37. ically identical For improved settability an optional three digit deca dial voltage control option 013 is available 1 6 Model 6104A Output Ratings The Model 6104A can be operated in either of two ranges 0 to 20V at 0 to 2A or 20 to 40V at Oto 1A Auto matic voltage range crossover occurs if the load current exceeds approximately 1A and the output voltage has been set above 20V 1 7 The front panel CURRENT control allows the maximum output current to be set to any desired value from 0 amps up to the maximum current rating for the range Using this control the power supply can be operated as a constant current source with 0 01 current regulation The front panel CURRENT MODE indicator lights when either the maximum gross current limit is reached or when the current l mit established by the front panel control is reached When the indicator s lighted the output voltage is uncalibrated However the front panel voltmeter continues to indicate the output voltage with an accuracy of 2 1 8 Model 6105A Output Ratings The Model 6 105A can be operated in either of two ranges 0 to 50V at 0 to 0 BA or 50 to 100V at 0 to 0 4A Automatic voltage range crossover occurs if the load current exceeds approximately 0 4A and the output voltage has been set above 50V 1 9 The Model 6105A can also be used as a cur rent source as described in paragraph 1 7 1 10 MODELS 6114A and 6115A 1 11 These models make use of a fron
38. ies or pass element that by varying its conductance in accor dance with error signals produced by the constant voltage and constant current comparators provides precise control of the output voltage and current during in range operation The regulator utilizes a power sharing circuit that results in consider ably less internal power dissipation than would be the case if a standard single stage regulator were employed This saving in dissipation is achieved by dividing the output of the supply into two reg ions the low and high voltage ranges and using separate raw dc supplies for each region range Maximum dissipation in any single stage regulator circuit occurs when the supply is short circuited at full output current under this condition the en tire raw dc voltage must be dropped across the series regulator while it is conducting the full out put current It can be seen then that if the raw dc voltage is made as low as possible when the supply is operating at a low output voltage the power dissipated in the series regulator will be minimized 4 3 The series regulator also includes a gross current limit circuit zener diode AIVR2 and associ ated resistors R5 R6 and R7 that overrides the error signal produced by the comparators if exces sive current is drawn when the output voltage is in the high range The following paragraphs discuss the operation of the 6104A 6114A series regulator during two modes of operation
39. ifferentials 4 29 The constant current comparator circuit con tinuously compares the voltage drop across the CURRENT control with the voltage drop across the current sampling resistor A1R15 If a difference exists the differential amplifier produces an error signal which is proportional to this difference The remaining components in the feedback loop driver and series regulator function to maintain the drop across the current sampling resistor and hence the output current at a constant value 4 30 One input pin 2 of the differential amplifier is connected to the inboard side of current sampling resistor A1R15 through matching resistors A2R11 and AlR18 Potentiometer A2R12 provides a vari able input bias that allows the output of the supply to be adjusted to zero current when the supply is set for zero output The other input to the differ ential amplifier pin 3 is connected to the summing point terminal A5 at the junction of the current programming resistor A1R2 and current program ming constant current source A2Q4 and A2Q5 Changes in the output current due to load changes or changes in the voltage at the summing point due to manipulation of the CURRENT control produce a difference voltage between the two inputs of the differential amplifier This difference voltage is amplified and appears at the output of the differen tial amplifier pin 6 as an error voltage which var ies the conduction of the series regulat
40. imize false triggering triggering of the SCR due to noise spikes Note alse that when the crowbar fires diode CR16 is forward biased as mentioned previously which forward biases front panel OVERVOLTAGE indicator DS3 which is a light emitting diode 4 56 A slaving arrangement of crowbar circuits in more than one unit is made possible by an extra secondary winding terminals 7 and 8 on transfor mer Tl Terminals on the rear barrier strip 413 and A14 allow easy connection to this winding Connecting these windings in parallel when opera ting in a multiple supply configuration will result in all the crowbars being activated if one of the crowbars is tripped To reset the crowbars in this arrangement all of the units must be turned off and then on Correct polarity A13 is positive must be observed when connecting the windings in parallel Figures 3 10 through 3 12 Parallel Auto Parallel and Auto Series demonstrate these connections Also the crowbars can be intercon nected down to a load impedance of approximately 10 each crowbar pulse winding has approximately 100 impedance after which considerable degrada tion of the pulse may occur 4 57 METER CIRCUIT 4 58 The meter circuit provides continuous indica tion of the output voltage and or output current Individual voltage and current meters are supplied in the 6104A and 6105A supplies while a single meter that can be used either as an ammeter or a voltmeter dependi
41. issipation Consider the case discussed in paragraph 4 40 where the supply output is 5 volts at 2 amps and the regulator is dissipating 48 watts If the supply used a conventional single stage regulator the raw dc source would have to be approximately 48V 20 higher than the maximum rated output voltage of 40V The power dissipated by the regulator would therefore be the voltage drop across it 43 volts times the current conducted 2A or 86 watts The use of the power sharing regulator thus repre sents a power dissipation saving in this particular case of more than 170 4 44 Refering back to paragraph 4 41 it was noted that since the output current is held by the con stant current comparator to 1A when the output vol tage is in the high range zener diode VR2 had no effect on circuit operation since the voltage across it does not exceed its breakdown voltage How ever assuming that the CURRENT control is set to 2A and the VOLTAGE control is still set at 40V if the load resistance decreases and attempts to draw more than approximately 1A through Qi and R5 the reverse voltage across VR2 exceeds the break down voltage of the zener diode At breakdown the diode becomes a constant current source and limits the current through the regulator to approxi mately 1 3A at nominal line voltage If load re sistance decreases further output voltage is re duced since the zener is a constant current source until the crossover
42. led on the power supply above their respective terminals The operator can ground either the positive or negative terminal or operate the power supply up to 300Vdc off ground floating The following paragraphs des cribe the procedures for utilizing the various oper ational capabilities of the power supply A more theoretical description concerning the operational features of this supply is contained in Application Note 90 and in various Tech Letters Copies of these can be obtained from your local Hewlett Packard field office 3 5 NORMAL OPERATING MODE 3 6 The power supply is normally shipped with its rear terminal strapping connections arranged for constant Voltage Constant Current local sensing local programming single unit mode of operation This strapping pattern is illustrated in Figure 3 2 Al A2 A3 A4 AS AG A7 eigiglelaiale WAW Ay Pigure 3 2 Normal Strapping Pattern 3 7 The operator selects either a constant voltage or a constant current output using the front panel controls for local programming no strapping changes are necessary Each supply is rated for two voltage and current ranges as follows Current 6104A 6114A 0 20V 0 2A 20 40Y 0 1A 6105A 6115A 0 50V 0 8A 50 100V 0 4A When the VOLTAGE and CURRENT settings are with in the specified ranges the constant voltage and constant current modes of operation are selected as described below If however VOLTAGE and CUR RENT settings are required
43. mum clockwise posi tion and turn off supply Tum supply back on and output voltage should again be value obtained in step d g To checkout the constant current circuit first tum off supply Short circuit front panel output terminals to On the 6114A or 6115A supplies set meter switch to AMPS Turn on the supply CURRENT MODE indicator comes on h Adjust CURRENT control through the en tire output current range as indicated on meter Adjust output for desired operating current _ i Remove short and connect load to output terminals Note that for maximum load protection by the crowbar the load should be connected to the rear terminals NOTE The power supply features automatic dual range operation If operating voltage and current are both set above the mid points of supply s voltage and current ratings the supply will gross current limit if current attempts to ex ceed one half the maximum current rating of the supply If output current increases further the supply enters the constant current mode in which output voltage is reduced in order to supply the desired current The VOLT AGE control setting therefore is overridden See paragraph 3 65 for more details 3 3 OPERATING MODES 3 4 The power supply is designed so that its mode of operation can be selected by making strap ping connections between particular terminals on the terminal strips at the rear of the power supply The terminal designations are stenci
44. near zero and OVERVOLTAGE indicator comes on turn off the supply and then disconnect any load from the power supply Turn the supply back on and determine if the crowbar again trips If it does there is a problem in the power supply Refer to Section V for troubleshooting procedures that can be used to isolate the cause of the overvoltage condition If the supply does not crowbar when the load is removed check the load circuit or the trip point setting 3 16 Crowbar Terminals Terminals Al3 and Al4 at the rear of the supply allow the crowbar trigger to be either monitored by an external circuit or to be used to trip crowbar circuits in other precision power supplies by interconnecting the A13 and Al4 terminals If precision power supply crowbars are to be interconnected be sure that all Al3 term inals the positive terminal are connected and all Al4 terminals are connected see figures 3 9 through 3 11 The crowbar trigger pulse specifi cations are given below and assume that no sup plies are interconnected Input Trigger Pulse Voltage 3V minimum 10V maximum Width between 90 point at leading edge and 90 point at falling edge 10usec minimum Output Pulse Voltage 5 1V Rise and Fall Time between 10 and 90 points 200nsec Width 1543yusec Load Impedance 10a min 3 17 CONNECTING LOAD 3 18 Each load should be connected to the power supply output terminals front or rear using separ ate p
45. ng on the position of the front panel METER switch S2 is provided in the 6114A and 6115A supplies The following paragraphs de scribe each of the two meter circuits 4 59 Dual Meter Circuit 6104A and 6105A To measure voltage the voltmeter and its series re sistors A1R20 and AIR22 are connected between the positive and negative sensing terminals Po tentiometer A1R22 allows the voltmeter to be cali brated For current measurements the ammeter is connected across the current sampling resistor Potentiometer A1R17 allows the ammeter to be cali brated Notice that during constant current opera tion the voltmeter and its resistors act as a shunt load across the output terminals of the supply drawing a small amount of current away from the load 0 1mA depending on the output voltage Voltage divider A1R18 and A1R21 compensates for this decrease in load current by subtracting a small voltage the drop across R18 from the voltage drop across the current sampling resistor The sub tracted voltage causes the constant current compar ator to increase output current just enough to bal ance the current supplied to the meter circuit 4 60 Single Meter Circuit 6114A and 6115A The voltage and current measuring circuits for the 6114A and 6115A are selected by front slide switch 52 and are similar to the associated dual meter circuit pre viously discussed For voltage measurements the meter and series resistors A1R17 ALR22 and A1
46. ntrols are set too low automatic crossover to constant current operation will occur and the output voltage will drop Remote sensing and programming can be used though the strapping arrangements shown in Figure 3 9 show local sens ing and programming Notice that the overvoltage crowbar terminals A13 and Al4 are connected in parallel which means that if any supply crowbars all supplies will be tripped 3 45 In order to maintain the temperature coeffic ient and stability specifications of the power supply the external resistors Ry shown in Figure 3 9 should be stable low noise low temperature coef ficient less than 5ppm per degree Centigrade re sistors The value of Ry is the maximum voltage rating of the master supply divided by the voltage programming current of the slave supply 1 Kp where Kp is the voltage programming coefficient The power rating of Ry should be at least 10 times the actual power dissipated in the resistor The voltage contribution of the slave is determined by its voltage control setting MASTER A8 5 5 Al3 Al4 21glPleigiaia 14 was ae a Ai A2 A3 A4 A5 AG A elalojolalalo ti Ea Ll MASTER AB 8 S AIS ANS aloe 9 lala adi id Al A2 A3 A4 AS AG AT ARALAR PL AR SLAVE NO t AB HAS S ASA HEERA A2 A3 A4 AS AG A Al glelglolaigie Ri SLAVE NO 2 ES S Al3 AB H ARABE EU O A
47. o d on the programming voltage source will not exceed luA Impedance matching resistor Rx is required to maintain the temperature coef ficient and stability specifications of the supply AI A2 A3 A4 AS AG AT REFERENCE VOLTAGE Remote Voltage Programming Constant Voltage Figure 3 4 3 29 REMOTE PROGRAMMING CONSTANT CURRENT 3 30 Either a resistance or a voltage source can be used to control the constant current output of the supply The CURRENT control on the front pan el is automatically disabled in the following pro cedures 3 31 Resistance Programming Figure 3 5 In this mode the output current varies at a rate determined by the programming coefficient as follows Model Programming Coefficient 6104A 6114A 500 ohms ampere 6105A 6115A 1 000 ohms ampere The programming accuracy is 0 25 of the program med value The output current of the supply when zero ohms is placed across the programming term inals may be set to zero by adjusting A2R12 as dis cussed in paragraph 5 95 At A2 A3 A4 A5 AG AT PROGRAMMING RESISTOR 9 S Al3 Al4 Figure 3 5 Remote Resistance Programming Constant Current 3 32 Use stable low noise low temperature co efficient at least less than 5ppm per degree Cen tigrade but preferrably 2ppm programming resis tors to maintain the power supply temperature co efficient and stability specifications A switch may be used to set discrete values of output cur
48. ode the output voltage will vary at a rate deter mined by the programming coefficient 2000 ohms Al A2 A3 A4 AS AG AT elelalgle PROGRAMMING RESISTOR Figure 3 3 Remote Resistance Programming p Constant Voltage per Volt i e the output voltage will increase 1 Volt for each 2000 ohms added in series with the programming terminals The programming accur acy is 01 of the programmed value 3 26 The output voltage of the power supply should be zero Volts 1 millivolt when zero ohms is con nected across the programming terminals The out put voltage may be adjusted closer to zero by ad justing potentiometer A2R13 as described in para graph 5 91 3 27 To maintain the stability and temperature co efficient of the power supply use programming re sistors that have stable low noise and low temp erature at least less than 5ppm per degree centi grade but preferrably 2ppm resistors characteris tics A switch can be used in conjunction with various resistance values in order to obtain discrete output voltages The switch should have make before break contacts to avoid momentarily open ing the programming terminals during the switching interval 3 28 Voltage Programming Unity Gain Figure 3 4 Employ the strapping pattern shown in Figure 3 4 for voltage programming with unity gain In this mode the output voltage will vary in a 1 to 1 ratio with the ptogramming voltage reference voltage and the l
49. ol Models 6104A amp 6114A 15mA Models 6105A amp 6115A 8mA REMOTE RESISTANCE PROGRAMMING Models 6104A amp 6114A 500 A 0 5 Models 6105A amp 6115A 1000 A 0 25 REMOTE VOLTAGE PROGRAMMING Models 6104A amp 6114A 0 5V A 1 Models 6105A amp 6115A 1V A 1 Specified with final decade potentiometer set to zero Tf potentiometer is set to value other than zero thermally induced resistance shifts may cause drift of 0 0015 200uV Potentiometer wiper jump effect may add 5mV 6104A or 10mV 6 105A When remote program med drift is 0 001 15V plus stability of remote programming device When remote programmed drift is 0 25 500A plus stability of remote programming device 1 18 OPTIONS 1 19 Options are customer requested factory mod ifications of a standard instrument All of the op tions described below apply to Models 6104A and 6105A All except option 013 apply to Models 6114A and 61154 Option No Description 008 Ten turn Output Current Control Replaces standard single turn cur rent control to allow greater resol tion in setting the output current of supply 013 Three Digit Graduated Decadial Yol tage Control Replaces standard 10 turn voltage control of Models 6104A and 61054 for improved output voltage settabil ity Option No Description 014 Three Digit Graduated Decadial Cur rent Control Includes 10 turn control replacing standard single turn current con
50. onstant current source it cannot be both Further as previously mentioned if the supply is set to operate outside of the specified high voltage range current rating i e both VOL TAGE and CURRENT are set to high values the supply will enter the current mode and limit output current if the load resistance attempts to draw more than one half of the maximum current rating of the supply As it limits output current the supply also lowers output voltage overriding the VOLTAGE setting until the low voltage range is reached At this point the supply enters the constant current mode in which the output current is maintained up to the maximum rating of the supply at the CURRENT setting by altering the output voltage 4 6 Figure 4 2 shows the output characteristics of a constant voltage constant current power sup ply When operated within either of the two nor mal output voltage current ranges 0 40V up to 1A or 0 20V up to 2A for the 6104A 6114A supplies or 0 100V up to 4A or 0 50V up to 8A for the 6105A 6115A supplies With no load attached R 00 loyy 0 and Eoyy Eg the front panel voltage control setting When a load resistance is applied to the output terminals of the power supply the output current increases while the output vol tage remains constant point D thus represents a typical constant voltage operating point Further decreases in load resistance are accompanied by further increases in Ip yy with no change
51. or assum ing the supply is in constant current operation in which case the output of the constant voltage com parator is approximately 15 5V which reverse biases OR gate diode A2GR2 4 31 The programming current constant current source Q4 and Q5 and associated components pro vides a constant current for the CURRENT program ming control Zener diode A2VR2 is a constant cur rent source and places the emitter of Q4 at a fixed 9 8V With the collector and base of Q4 strapped together the transistor acts as a diode and drops 7V so that the base of Q5 is held at a positive voltage and the transistor is forward biased sup plying a fixed constant current to the programming control Potentiometer A2R19 allows the constant programming current to be precisely set at the full output current rating of the supply see Section V for calibration procedures 4 32 DRIVER CIRCUIT 4 33 The driver amplifies the error signal from the constant voltage or constant current input circuit to a level sufficient to drive the series regulating transistors Transistor A1Q1 receives the error voltage input from either the constant voltage or constant current comparator via the OR gate diode A2CR2 or A2CR3 that is conducting at the time Diode CR2 is forward biased and CR3 is reverse biased during constant voltage operation The re verse is true during constant current operation 4 34 Predriver transistor A1Q1 receives the error signal and applies
52. ote programming modes 3 41 SERIES OPERATION 3 42 Normal Series Connections Figure 3 8 Two or more power supplies can be operated in series to obtain a higher voltage than that available from a single supply When this connection is used the output voltage is the sum of the voltages of the in dividual supplies Each of the individual supplies must be adjusted in order to obtain the total output voltage The power supply contains a protective diode connected internally across the output which protects the supply if one power supply is turned off while its series partner s is on Al A2 A3 A4 AS AG A La Ad Ly La 9 S AIZAI4 A8 eigigigigieie aii wi Al AZ A3 A4 AS AG A a A Lu Ld waw AN S S AIS AIS Qlalela 22 EF WF j Figure 3 8 Normal Series 3 43 AUTO SERIES OPERATION Figure 3 9 3 44 Two or more power supplies can be operated in Auto Series to obtain a higher voltage than that available from a single supply When this con nection is used the output voltage of each slave supply varies in accordance with that of the master supply thus the total output voltage of the com bination is determined by the setting of the front panel VOLTAGE controls on the master The master supply must be the most positive supply of the series The output CURRENT controls of all series units are operative and the current limit is equal to the lowest control setting If any of the output CURRENT co
53. ource will be less than luA Impedance matching resistor Rx is required to maintain the temperature coefficient and stability specifications of the supply Al A2 A3 AG AS AG A7 REFERENCE y VOLTAGE AS zS Al3 Al 4 22121212 2 2 di y i Figure 3 6 Remote Voltage Programming Constant Current 3 35 The output current of the supply may be ad justed to exactly zero when the external program ming voltage is zero by adjusting resistor A2R12 as discussed in paragraph 5 95 3 36 REMOTE SENSING Figure 3 7 3 37 Remote sensing is used to maintain good reg ulation at the load and reduce the degradation of regulation which would occur due to the voltage drop in the leads between the p wer supply and the load Remote sensing is accomplished by utilizing the strapping pattern shown in Figure 3 7 The power supply should be turned off before changing Strapping patterns The leads from the sensing 5 terminals to the load will carry much less cur rent than the load leads and it is not required that these leads be as heavy as the load leads How ever they must be twisted or shielded to minimize noise pickup 3 6 AI A2 A3 A4 AS AG A7 alalplola lalo Led od ke LL A8 5 S AIZ AIG Figure 3 7 Remote Sensing 3 38 For reasonable load lead lengths remote sensing greatly improves the performance of the Supply However if the load is located a con siderable distance from the supply added precau tions m
54. output will act as a constant current source dropping its output voltage until it equals that of the other supply The con stant voltage source will deliver only that fraction of its total rated output current which is necessary to fulfill the total current demand Al A2 A3 A4 AS AG A7 UF Wet ba bad es Y LA pA nTa 2 o o 2 BI a Al AZ A3 A4 A5 A6 A Figure 3 10 Normal Parallel 3 49 AUTO PARALLEL OPERATION Figure 3 11 3 50 Two or more power supplies can be connect ed in an Auto Parallel arrangement to obtain an output current greater than that available from one supply Auto Parallel operation permits equal cur rent sharing under all load conditions and allows complete control of the output current from one master power supply The output current of each slave will be approximately equal to the master s output current regardless of the load conditions Because the output current controls of each slave are operative they should be set to maximum to prevent the slave reverting to constant current op eration this could occur if the master output cur rent setting exceeded the slave s 3 51 Additional slave supplies may be added in parallel with the master slave combination All the connections between the master and slave 1 are duplicated between slave 1 and the added MASTER Al A2 A3 A4 AS AG AT S S AIS AI4 alglelelelale elglelelelele Nenn gt Fol ME PAJA ojojejaajo ejejoJejele
55. rent A make before break type of switch should be used since the output current will exceed the maximum rating of the power supply if the switch contacts open during the switching interval CAUTION If the programming terminals A6 and should open at any time during the re mote resistance programming mode the output current will rise to a value that may damage the power supply and or the load If in the particular program ming configuration in use there is 4 chance that the terminals might become open it is suggested that a 1 0Ka resistor be connected across the pro gramming terminals Like the pro gramming resistor this resistor should be a low noise low temperature coef ficient type Note that when this re sistor is used the resistance value actually programming the supply is the parallel combination of the remote pro gramming resistance and the resistor across the programming terminals 3 33 Voltage Programming Figure 3 6 In this mode the output current will vary linearly with changes in the programming voltage The program ming voltage must not exceed 1 0 volt Voltage in excess of 1 0 volt will result in excessive power dissipation in the instrament and possible damage 3 34 The output current varies at a rate determined by the programming coefficient as follows Model Programming Coefficient 6104A 6114A 0 5 volts ampere 6105A 6115A 1 0 volts ampere The current required from the voltage s
56. rument is received proceed as instnicted in the following paragraphs l 2 3 MECHANICAL CHECK 2 4 If external damage to the shipping carton is evident ask the carrier s agent to be present when the instrument is unpacked Check the in strument for external damage such as broken con trols or connectors and dents or scratches on the panel surfaces If the instrument is damaged file a claim with the carrier s agent and notify your local Hewlett Packard Sales and Service Office as soon as possible see list at rear of this manual for addresses 2 5 ELECTRICAL CHECK 2 6 Check the electrical performance of the in strument as soon as possible after receipt Sec tion V of this manual contains performance check procedures which will verify instrument operation within the specifications stated in Table 1 1 This check is also suitable for incoming quality control inspection Refer to the inside front cover of the manual for the Certification and Warranty state ments 2 7 REPACKAGING FOR SHIPMENT 2 8 To insure safe shipment of the instrument it is recommended that the package designed for the instrument be used The original packaging mater ial is reusable If it is not available contact your local Hewlett Packard field office to obtain the materials This office will also furnish the address of the nearest service office to which the instrument can be shipped Be sure to attach a tag to the instrument specifying the owner model
57. s each supply is rated for two voltage current ranges Although the supply can be operated in this shaded region without being damaged it cannot be guaranteed to meet all of its performance specifications Generally when operating the supply in this manner the output is unstable when a load is connected However if the line voltage is maintained above its nominal value the supply will probably operate within the specifications above the rated output In addition the supply may be operated slightly above approx imately 130 at nominal line voltage the voltage current range specifications i e at about 1 3A up to 40V for the 6104A 6114A or at about 0 52Aup to 100V for the 6105A 6115A or at 2A up to 26V for the 6104A 6114A or 8A up to 65V for the 6105A 6115A In these operating regions however the supply is in gross current limit and certain power supply specifications such as ripple etc are degraded 3 23 REMOTE PROGRAMMING CONSTANT VOLTAGE 3 24 The constant voltage output of the power supply can be programmed controlled from a re mote location if required Either a resistance or voltage source can be used as the programming device The wires connecting the programming terminals of the supply to the remote programming device should be twisted or shielded to reduce noise pickup The front panel VOLTAGE control is automatically disabled in the following procedures 3 25 Resistance Programming Figure 3 3 In this m
58. t panel mounted four digit pushbutton control to increase and decrease output voltage in unit steps A thumbwheel control is used to set the fifth or least significant digit for output voltage accuracy in the fractional millivolt range A single meter combining both voltage and current functions is also located on the front panel A METER slide switch selects the function to be indicated on the meter With the exception of sume component val ues and meter scale markings the 6114A and 6115A are physically identical 1 12 Model 6114A Output Ratings The Model 6114A can be operated in either of two ranges 0 to 20V at 0 to 2A or 20 to 40V at Oto 1A Auto matic voltage range crossover occurs if the load current exceeds approximately 1A and the output voltage has been set above 20V 1 13 The Model 6114A can also be used as a Cur rent source as described in paragraph 1 7 1 14 Model 6115A Output Ratings The Model 6115A can be operated in either of two ranges 0 to 50V at 0 to 0 8A or 50 to 100V at 0 to 0 4A Automatic voltage range crossover occurs if the load current exceeds approximately 0 4A and the output voltage has been set above 50V 1 15 The Model 6115A can also be used as a cur rent source as described in paragraph 1 7 1 16 SPECIFICATIONS 1 17 Detailed specifications for all four models are given in Table 1 1 Table 1 1 NOTE Specifications apply to all models unless otherwise indicated IN GENERAL
59. t produce a difference voltage between the two inputs of the differential amplifier This difference voltage is amplified and appears at the output of the differential amplifier pin 6 as an error voltage which ultimately varies the conduct ion of the series regulator 4 24 Resistor R15 in series with the summing point input to the differential amplifier Limits the current through the programming resistors during rapid voltage turn down Diodes CR5 and CR6 pre vent excessive voltage excursions from over driv ing the differential amplifier Notice that when the power supply is in the constant current mode the output of the voltage differential amplifier A2U2 approximately 15 5V with respect to and turns on transistor A2Q3 thereby turning on the front panel CURRENT MODE indicator DS2 a light emitting diode Triple junction diode CR7 provides sufficient voltage drop to keep Q3 cutoff when the supply is in constant voltage mode 4 25 During constant voltage operation the pro gramming current flowing through the programming resistor s VOLTAGE control is held constant be cause of selectable resistor A2R3 and potentiometer A2R5 which allow the 16V reference to be calibra ted The reference voltage is dropped across high tolerance 05 current pullout resistor A2R24 thereby assuring a constant current flow through the VOLTAGE programming resistors See Section V for procedures to be used in calibrating this refer enc
60. that are outside of the specified ranges for normal operation for instance the 6104A is set for 30V and 1 5A the power sup ply provides automatic dual range switching if output current attempts to exceed the low range cur rent rating As current is limited to approximately 65 of the maximum low range rating at nominal line voltage the VOLTAGE setting is overridden and output voltage is reduced to the low range approximately 65 of the maximum high range voltage rating at nominal line voltage The supply next enters the constant current mode during which output voltage is reduced in order to supply the de sired current Refer to paragraph 3 65 for more in formation on how the supply operates to gross cur rent limit and automatically switch ranges 3 8 CONSTANT VOLTAGE 3 3 To select a constant voltage output within the normal range ratings of the supply proceed as follows l a Remove load from output terminals turn on supply and adjust VOLTAGE control for desired output voltage b Short output terminals and adjust CURRENT control for maximum output current allowable cur rent limit as determined by load conditions and voltage range selected in step a If a load change attempts to cause the output current to exceed this setting the power supply will automatically cross over to constant current mode and output current will be constant at the level set by the CURRENT control The CURRENT MODE indi
61. towards o 4 54 When triggered the SCR has two paths through which it conducts current as follows Assuming the series regulator transistors Q2 and Q3 are not open diode CR16 is forward biased when the SCR fires and the output current flows from the output terminal the base emitter junc tions of Q2 Q3 the 7 5V supply this diode and through the SCR Thus current is diverted from the series regulator transistors and the output cur rent and of course voltage is turned down rapidly The current surge through the SCR therefore is minimized The other current path for the SCR is via diode CR17 and the output terminals However if the series regulator transistors are operable most current flows through the CR16 path In the case when the series regulator transistors collector emitter junction shorts which would open the CR16 current path described above the SCR will con duct all the current through this path the current surge will however be sustained for a longer time until the supply fuse opens Diode CR17 assures that the CR16 path is not turned on during normal operation when output voltage is set below 7 5V 4 55 Resistor R27 limits the current flowing into the gate of the SCR and diode CR18 prevents ring ing in the pulse transformer when the positive trigger pulse collapses Resistor R34 limits the current flowing through the SCR and inductor L1 is included to decrease the response time of the SCR and min
62. trol for greater resolution in setting the output current of supply 040 Interfacing for Multiprogrammer Oper ation Prepares standard HP power supplies for resistance programming by the 6940A Multiprogrammer or 6941A Multiprogrammer Extender Operation with either of these instruments re quires that the power supply be sub jected to 1 Special Calibration and 2 Protection Checkout The former procedure insures that the power sup ply can be accurately set to zero and 1 3 the maximum rated output voltage or current when programmed by the Multiprogrammer the latter pro cedure insures that the power sup ply will not be damaged by the rapid repetitive programming pos sible with the Multiprogrammer 1 20 ACCESSORIES 1 21 The accessories listed in the following chart may be ordered with the instrument or separately from your local Hewlett Packard sales office refer to list at rear of manual for addresses HP Part No Description 5060 8762 Dual Rack Adapter Kit for rack mounting one or two supplies in standard 19 inch rack 5060 8760 Blank Panel Filler panel to block unused half of rack when mounting only one supply 1052A Combining Case for mounting one or two units in standard 19 rack 5060 0789 Cooling kit for above combining case 115Vac 50 60Hz 5060 0796 Cooling kit for above combining case 230Vac 50 60Hz 1 4 1 22 INSTRUMENT IDENTIFICATION 1 23 Hewlett Packard power supplies are identif
63. ulator in the correct phase and amplitude to counteract the difference In this manner the constant vol tage comparator helps to maintain a constant out put voltage and also generates the error signal necessary to set the output voltage at the level established by the VOLTAGE controls 4 4 During constant current operation the con stant current comparator detects any difference be tween the voltage drop developed by the load cur rent flowing through the current sampling resistor and the voltage across the CURRENT control If the two inputs to the comparator are momentarily unequal an error signal is generated which after amplification alters the conduction of the series regulator by the amount necessary to reduce the error voltage at the comparator input to zero Hence the IR drop across the current sampling re sistor and therefore the output current is main tained at a constant value 4 5 The constant voltage comparator then tends to achieve zero output impedance by altering the output current whenever the load resistance changes Conversely the constant current com parator attempts to achieve infinite output imped ance by changing the output voltage in response to any load resistance changes Thus it is obvious that the two comparison amplifiers cannot operate simultaneously When the supply is operated within the two normal ranges of output voltage current it must act either as a constant voltage source or as a c
64. upply and if it exceeds a pre set adjustable threshold fires an SCR which ap plies a virtual short circuit across the supply thus reducing the output voltage to approximately zero 4 11 The meter circuit provides a continuous indi cation of the output voltage and or current of the supply two meters are provided in the 6104A and 6105A models Output voltage is sensed directly across the sensing terminals while output current is sensed by monitoring the IR drop across the cur rent sampling resistor 4 12 DETAILED CIRCUIT ANALYSIS 4 13 GENERAL 4 14 Except for differences due to the different voltage current ratings of the power supplies and the different VOLTAGE controls and meter circuits employed all of the supplies operate in a similar fashion Since the supplies are similar two schem atics have been provided one for the dual meter ten turn VOLTAGE control supplies the 6104A and 6105A and one for the single meter pushbutton VOLTAGE control supplies the 6114A and 6115A Generally then the following discussions apply to the 6104A 6114A 6105A or 61154 supplies For clarity however certain circuits i e the series regulator are discussed for specific supplies the 6104A 6114A Except for the different voltage and current values these discussions apply equal ly to the other supplies Further where specific differences in circuit operation exist between power supply models they are discussed for each supply
65. urbance level 4 18 CURRENT FEEDBACK LOOP 4 19 When operated within either of the two spec ified range ratings if the external load resistance decreases below the crossover point discussed in paragraph 4 7 the supply will operate in the constant current mode In this mode the feedback loop la to maintain the output current at a constant level For purposes of this discussion assume that the output current instantaneously rises goes positive due to a change in the exter nal load circuit This current change causes the voltage across the current sampling resistor to rise this change is coupled through front panel CURRENT control R2 to summing point A5 and thus to pin 3 of the constant current comparator as a decreasing less positive input The output of the comparator then decreases This negative going error voltage is coupled through OR gate diode A2CR3 to pre driver AlQ1 At this point the voltage and current feedback loops are joined As discussed in paragraph 4 17 the negative going error voltage is amplified in pre driver AlO1 and fed through driver Q4 mounted on the heat sink to the series regulator The series regulator thus de creases its conduction and returns the output cur rent to the original pre disturbance level by de creasing output voltage 4 20 CONSTANT VOLTAGE COMPARATOR 4 21 The constant voltage comparator consists of the VOLTAGE programming resistors R4 for models 6104A 6105A and A3R1 AB3R17 for
66. ust be observed to obtain satisfactory oper ation Notice that the voltage drop in the load leads subtracts directly from the available output voltage and also reduces the amplitude of the feed back error signals that are developed within the unit Because of these factors it is recommended that the drop in each load lead not exceed 1 0 volt If a larger drop must be tolerated please consult an HP Sales Engineer NOTE Due to the voltage drop in the load leads it may be necessary to readjust the constant current setting in the re mote sensing mode l 3 39 Observance of the precautions in paragraph 3 37 will result in a low de output impedance at the load However another factor that must be considered is the inductance of long load leads This causes a high ac impedance and could affect the stability of the feedback loop seriously enough to cause oscillation In this case it is recom mended that the following precautions be taken a Disconnect output capacitor C12 by un strapping terminal A8 b Connect a capacitor having similar char acteristics approximately the same capacitance the same voltage rating or greater and having good high frequency characteristics across the load us ing short leads 3 40 Although the strapping patterns shown in Figure 3 3 through 3 6 employ local sensing note that it is possible to operate a power supply simul taneously in the remote sensing and constant volt age constant current rem
67. ver control on the front panel The trip voltage range of the crowbar is approximately 0 5 to 45Vda for the 6104A and 6114A supplies and 0 5 to 110Vdc for the 6105A and 6115A supplies To set the crow bar trip voltage perform the following procedures NOTE Do not connect a load to the power supply when setting the crowbar trip voltage a Turn OVERVOLTAGE control fully clock wise and turn on supply b Set output voltage to desired trip voltage If the desired trip voltage is above 40 volts for the 3 3 6114A or 100 volts for the 6115A perform the next step if the desired trip setting is within the max imum voltage rating of the 6114A or 6115A supplies or in order to set the trip voltage for the 6104A and 6105A supplies go on to step d c H the output of the 6114A or 61154 can not be set to the desired crowbar trip voltage 1 Turn off the supply 2 Disconnect the voltage programming pushbutton switch assembly two wires connect the switch assembly to Main Power Supply Board Al 3 Temporarily connect an external re sistor 5 1 2W in place of the voltage program ming resistor according to the following formula Eour 5mA X R Where Eoyr is the desired output voltage 5mA is the voltage programming current amp R is the external resistor For example connect a 90Kn 5 1 2W resistor if the 6114A is to be set to 45V or a 220Kn 5 1 2W resistor if the 6115A is to be set to 110V 4 Turn onthe supply
68. vity and bandwidth 50uV om and 300KHz for all measurements except noise spike imV and 20MHz for noise spike measurement Sensitivity ImvV full scale min Accuracy 1 Sensitivity SOpV full scale min Frequency range 5Hz to 250kHz min Accuracy 3 Frequency range 5Hz to 20KHz min Output 5V rms into 6000 Accuracy 3 Power output 50 watts Frequency response 3dB 5Hz to 20kHz min repeat the performance check to ensure that the fault has been properly corrected and that no other faults exist Before performing any maintenance checks turn on the power supply and allow a half hour warm up 5 3 TEST EQUIPMENT REQUIRED 5 4 Table 5 1 lists the test equipment required to perform the various procedures described in this section Test Equipment Required RECOMMENDED MODEL i HP 3420B See Note on Page 5 2 Measure de voltages cali bration procedures HP 140A with 1403A vertical plug in and 1423A time base HP i 180A with 18034A vertical plug in and 1820A time base for spike measurement HP 412A Measure output impedance HP 3410A ripple and ac voltages HP 209A HP 6824A Measure ripple display transient recovery wave forms measure noise spikes Measure de voltages Measure output impedance Measure output impedance
69. w voltage range Since the gross current limit circuit is not as precise as the con stant voltage and current comparators the maxi mum voltage and current outputs of the supply dur 130 OF MAX Hi RANGE CURRENT zg MAXHI RANGE RATING t Es t GROSS CURRENT LIMIT REGION y 130 OF MAX lt f LOW RANGE 20V 810447 m VOLTAGE 61144 LOW RANGE VOLTAGE CURRENT LIMITS SOV 6 05A 6H5A EQUT E 1 g lt MAX CURRENT eT max RATING IA 6109A 6114A 0 4A 61054 61154 HIGH RANGE VOLTAGE CURRENT LIMITS Toyp TT Figure 4 3 Operating Locus of Supply When Operated Out of Voltage Current Range Limits 4 3 ing gross current limit is slightly above the maxi mum ratings of the supply thus allowing for a mar gin of safety in that the supply will provide up to approximately 130 of high voltage range current rating and conversely it will supply 130 of low voltage range voltage while supplying maximum current if operated in this region however power supply specifications such as output ripple are ad versely affected 4 9 The reference supply provides stable refer ence voltages used by the constant voltage compar ator the constant current comparator and the dri ver In addition unregulated 28V is supplied to front panel indicator circuits Less critical opera ting voltages are provided by the bias supply 4 10 The overvoltage protection crowbar monitors the output of the s

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