User Manual - Schulz Electronic GmbH
Contents
1. Pic LAS D DVN D U S e r M a n u a Rev 09 01 valid from June 2009 LDP C 200 20 PicoLAS GmbH Company for Innovative Power Electronics und Laser Technology Kaiserstra e 100 52134 Herzogenrath Tel 49 0 2407 563 58 0 Fax 49 0 2407 563 58 29 E Mail info picolas de Web www picolas de Pic LAS FOCUSSING POWER TO THE POINT Table of Contents LID P 200 20 a sac naan a aa eaeds nese cans aadeos AE E ERE E ONEA 3 Description of Connections and JUMPS cccceceeeeeeeeeeeeeeeeeeeeeeeeeeecaeeceeseeetseeteeeteeeteeetseetieens 4 HOW to GetStarted c sce caccaecceecaseetpacczsnassudecacaaesentactadn ed qpancdeeassadenadaieehsdaiiessedapadedstanseaetegeae iets 5 Dos and Don ts LDP C 200 20 0 cccecececcccccecccecesssseececececennnseeeeecesesensssssesesevesennttseeseeevesennees 6 Product Specification Ea Avy ceet asain R teenie E nite eke xs tee an 7 Operating Rage enms srin raa E heel ae E saben ad Sensei sano ae Senet EA ads 8 Functional IDGSEFPTIOM ce cee Hee ac ten tsttlata e e ae EEA E E ae EEA ives 9 interface Specification rane ENEE E A EEEN TONE EEEE ERANG AN 10 Current Rise Time ACjUStment ccccccccecececeeeeeceeeeceeeeeceeeceeeeeeaeeeceeeceaeeeceeeseaeeseceeecneeeesieeenaes 11 Effect of Laser Diode Connection on the Pulse Shape eccccceeeesceeeeeeeeeeeeeeeeseeeenseenseeneeneees 11 TSU LOG es vgs ce sctsansieiesns E tseeadendsaaeacts ia ha tedeasunetaben E ants teeate 11 VED Stats IN2. the rise time increases With the poti trise on the controller board the user can influence the voltage rise of the output voltage of the pulser and thus the rise time of the laser diode current However as the rise time depends mainly on the cabling as well as on the chosen current and compliance voltage of the load no absolute relation for the current rise time can be given Bypass Effect of Laser Diode Connection on the Pulse Shape Parasitic elements in pulser and connection line to the laser diode have an important influence on pulse shape and rise time The parasitic output capacitance of the pulse Cpar the cabling inductance Leable and the parasitic capacitance of the diode Caiode form a resonant circuit Applying a step function which is done at the beginning of a pulse on a resonant circuit results in oscillations and current overshoot As these oscillations are inacceptable for most laser applications the parasitic capacitances and inductances have to be minimized Laser diodes usually have a very low parasitic capacitance in the order of some 10 pF Together with a short and low inductive connection between laser diode and driver no oscillations or overshoot should occur In addition the adjustable current rise time helps to avoid overshoot and oscillations A very short rise time and thus a very high current rise results in a strong excitation of the resonant circuit With a longer rise time and softer current rise the resonant
3. GICAUOMS ieseana ive padyesceay ocks sa categadaead a a aaa 12 Absolute Maximum RatingS cccccccecececeeeeeceeeeeeeeeeceeeecneeeeceeeecceeeeteeeceeeesneeeecieessneeeseteeeeneeees 12 Mechanical DimensiOns cccccccceceeeceeeeeeceeeeeeeeeeceeeceeeeeceeeceeeeeceeeceeeeceeeecieeecnieeesteeenieeeesees 12 LDP C 200 20 Pic LAS FOCUSSING POWER TO THE POINT Rev 09 02 valid from June 2009 Driver for High Power Laser Diodes i Ch2 SO0OmY Q Bw M 200ps 250NIS s 4 0nsipt A s 490my Figure Current monitor output scale 50A Div Product Description The LDP C 200 20 OEM is a compact high power current supply to drive almost any kind of Laser Diode The pulsing capability ranges from single pulses over hundred kilohertz repetition frequency up to continuous operation Pulses are generated by shorting the output thus the current between two pulses equals zero Several analog Inputs and monitor outputs provide an easy way to control the LPD C In combination with the PLB 21 the LDP C 200 20 is capable of generating pulses on its own No external Pulse generator is required and all parameters can be comfortably adjusted The innovative current regulation concept of the LDP C 200 20 produces compared to the commonly used linear regulation concept considerably less losses e Output current 10 200A e Output current between pulses 0 A e Compliance Voltage 2 20 V e Coverage of both cw a
4. TO THE POINT Description of Connections and Jumpers The following drawing shows all connections potis and jumpers which are available to the user The upper drawing shows the controller the lower shows the power board RS232 BOB Iset Trise J1 L J2 ker tise J 1 LEDI LED2 controller board power board RS232 connector See page 10 for detailed information Break out board connector See page 10 for detailed information Poti for current setpoint only active when PLB 20 disabled and J1 in position 1 2 Poti for current rise time adjustment Selects current setpoint input only active when PLB 20 disabled 1 2 internal poti 2 3 external input BOB connector PLB 20 communication 1 2 enable 2 3 disable Green status LED See page 12 for detailed information Red status LED See page 12 for detailed information Supply voltage Supply ground Positive laser diode output anode Negative laser diode output cathode Do not connect to ground Positive temperature regulated fan output 12 V 0 4 A Negative fan output Do not connect to ground Pic LAS FOCUSSING POWER TO THE POINT How to get started Step What to do Note 1 Unpack your Device 2 Apply a dummy load at the output e g a Dummy load must be a valid equivalent Fast Recovery Diode to a laser diode e g concerning parasitic capacitance 3 Turn the output current setpoint poti to the lowest value turn Poti fully countercloc
5. at the output 02 Flashes 2x System power up Check power supply Running self test If device is not continuously on after a few seconds the power supply might be too low or too high 03 Flashes 3x 3x off Enable not connected 10 ara On Temperature above chosen Maximum above chosen Maximum Let device cool down 11 Cont On Sa 1x Device is cooling ee switching off Let device cool down because of over temperature 12 Cont On flashes 2x Temperature approaching switch off Potentially additional temperature cooling with a fan 13 flashes 3x Internal Fault DAC not addressable Repair needed 14 Don t care flashes 4x Internal Fault Temperature sensor Repair needed failed 15 flashes 2x flashes 5x Minimum Voltage Fault Adjust power supply Power supply is below 18 V 16 flashes 2x flashes 6x Overvoltage Fault Adjust power supply Power supply exceeds 27 V Absolute Maximum Ratings Supply voltage range Vcc 18 UVLO to 27 V OVLO Input current 200 A Laser diode output current 210 A Laser diode output voltage Vcc 2 V Pulse repetition rate 200 kHz BOB connector input and output voltages 0 V to 5 V BOB connector output currents 1 mA Auxiliary 5 V supply voltage output current 30 mA RS232 connector 30 V Fan output current 500 mA fused Operating temperature 0 55 C Mechanical Dimensions Eingang Out 24V Out Out Out Eingang GND L fter ausgang 12
6. circuit is considerably less excited and though oscillations and overshoot will not appear As already mentioned above Leable influences the current rise time at the beginning of the pulse Because Leable has to be magnetized up to the inductor current which flows through Ly a higher Leable yields in a longer rise time At the end of a pulse 3 closes and shorts the output Then Liable has to be demagnetized At this time only a very low voltage is available at the output The time required to demagnetize Leable depends only on its value Higher Leabie results in a longer current fall time Test Load A common method to test the driver is to connect a regular silicon rectifier diode to the driver output Here has to be paid attention to the junction capacitance of the diode Only fast recovery diodes or similar have a low parasitic capacitance as laser diodes have To achieve reasonable test results the parasitic elements of the test diode and the connection must be very similar to a laser diode approach Regular silicon rectifier diodes have a junction capacitance of several microfarads and are not a suitable test load The use of these diodes will yield in incorrect current measurement at the pulse edges 11 Pic LAS FOCUSSING POWER TO THE POINT LED Status Indications Nr Green LED Red LED Description Solution if applicable 01 Cont On Off Ready for operation a pulse at the Trigger input will be followed by the reaction
7. controller is capable of generating pulses with a configurable repetition rate and duration on its own but also allows throughput of the external trigger input Several security features protect the laser diode and driver from damage The microcontroller supervises driver temperature inductor current input and output voltage and disconnects the driver from the power supply in case of an error by opening the security switch So D3 protects the laser diode from reverse currents bypass diode D4 protects the driver in case of a load failure Bypass Measured Variables amp Trigger Element Function S Security Switch G S S D D Buck Converter S gt Shunt Mosfets Short Output D D LD Protection Rs Current sensor for Regulation Control R LD current monitor Temperature sensor uC RS232 communication Temperature supervision Current control Pic LAS FOCUSSING POWER TO THE POINT Interface Specification The following figure shows the input and output stages of the external analog connector The monitoring outputs are filtered and buffered to improve signal quality Digital inputs enable and pulse trigger are filtered to reduce spikes and then evaluated by Schmitt triggers to ensure proper evaluation The external current setpoint input is filtered and then sampled by the microcontroller All inputs are protected by clamping diodes against over voltage An auxiliary high impedance 5 V supply voltag
8. e is provided to power e g the LDP C BOB 2 2kQ setpoint 7 5v1 1nF Took l 4700 4700 diode 220pF 470Q L 1 induct m 100pF 470Q a enable 0 A 5 ee m ontro 5v7 amp 22kQ uC 470Q I pulse 5v17 1 2nF 22kQ GND ag al 5V U 330 470Q Doa mi a 220pF The RS232 interface is mainly designed to communicate with the PLB 20 Thus it contains two additional supply voltages to power the PLB 20 10 Pic LAS FOCUSSING POWER TO THE POINT Current Rise Time Adjustment The LDP C 200 20 provides current rise time adjustment of the positive edge of a pulse When the shunt switch S3 closes the inductor current through Ly commutates from S3 to the output There it has to magnetize the parasitic inductance Liable of the cabling between pulser and laser diode During this process the current through the laser diodes rises The time during which the laser diode current rises depends on the voltage difference between the output of the pulser and the laser diode compliance voltage the current through Ly and the parasitic inductance itself Obviously higher parasitic inductance result in slower current rise and thus higher rise time Equally a higher current results in a higher rise time With a higher compliance voltage the voltage difference between pulser output and laser diode decreases and though
9. ent below 40 A results in a relative high current ripple c This won t do any harm to the driver but is for some applications not acceptable For currents below 40A we recommend e g the LDP C 40 05 LNA esee nanan eee 150 100 25 U inV Legend a Area of best performance b Compliance voltages below 4 V and above 20 V will cause a longer tailing of the current or a current droop at the beginning of the pulse c Currents below 40 A result in relative high current ripple Pic LAS FOCUSSING POWER TO THE POINT Functional Description The LDP C 200 20 operates by the following principle A buck converter S S2 D D2 Ly generates a current in its inductor Ly This current is shorted to ground through the shunt MOSFET S3 During a pulse S3 is open and the current flows through the laser diode Lp The inductor current through Ly is measured with Rs1 this allows the control circuit to regulate the current to a constant value under all circumstances The laser diode current is measured with Rsz Blocking capacitors decouple the driver from the power supply C filters the high frequency ripple of the buck converter C provides the pulse energy Inductor current laser diode current and compliance voltage are preprocessed and then lead to an external connector A trigger input for generating pulses as well as an enable input is available An RS232 interface allows communication with a PLB 20 or a PC The integrated micro
10. kwise 4 Connect a Pulse source to the triggering Input e g 100 us 5 V TTL 100 Hz 5 Connect your Scope to the diode current Select high impedance termination monitor output Ipioge trigger on positive rising edge 500 mV div 6 Apply the supply voltage 24 V DC Make sure that the supply voltage can deliver enough energy to be stable during the pulses 7 Set enable pin high To protect your Laser Diode the Driver will stay disabled if the enable Pin is high during power up 8 Adjust the pulse current value to the desired Turn poti clockwise and observe the value current on the oscilloscope 9 Disconnect the supply remove the dummy To protect your Laser Diode the Driver load at the output and assemble the Laser will keep disabled if the enable Pin is Diode Polarity high during power up Pic LAS FOCUSSING POWER TO THE POINT Dos and Don ts LDP C 200 20 Never ground any lead of the output This will immediately destroy the driver Never use any grounded probes at the output This will immediately destroy the driver and the probe Never make a short at the output This will not do any harm to the laser driver but will yield in an incorrect current measurement Always use all four terminals at the driver s output This will reduce the stray impedance of the connection and yields better performance of the internal current monitor Using only two terminals will result in excessive heat p
11. nd qcw range e Several protective features e Adjustable current rise time e Max Output Power 4000 W Technical Data Output current 10 200A Max compliance voltage 20V Typ pulse rise time 100 A 0 8 5 us Typ pulse trigger delay 2 6 ps Min pulse duration 100 A lt 5 us Max pulse duration cw Max repetition rate 100 A gt 100 kHz Current ripple lt 2 5 A gt 20 kHz Current overshoot lt 5 Current settling time lt 100 ms full scale Pulse trigger input 5 V TTL into 500 Q PLB 20 0 2 V external 100 A V Internal poti PLB 20 100 A V 0 1 VV 24V DC 145 x 107 x 90 Current setting input Current monitor Voltage monitor Supply voltage Dimensions in mm Operating temperature O to 55 C Weight 1582 g Specifications measured with a fast recovery diode instead of a laser diode Technical data is subject to change without further notice See User Manual for Details Designed to shield your laser diode from damage the LDP C 200 20 features a number of powerful protective safeguards e Innovative current regulation concept actively prevents laser diode from overshoots and over current e Protection against transients through regulated current rise time e Over temperature shutdown e Enable Disable input e Shunt MOSFETs short the output clamps in case of an error e Protection of the laser diode against reverse currents Pic LAS FOCUSSING POWER
12. roduction at the terminal itself and may damage driver and cable Keep connection between power supply and the driver as well as the connection between driver and laser diode as short as possible Mount the driver on an appropriate heat sink Attach a fan to the temperature regulated fan output The fan should cool the heat sink and the driver itself Pic LAS FOCUSSING POWER TO THE POINT Product Specification Output current 10 200 A Current between Pulses OA lt 1 Parasitic voltage between lt 150 mV poles measured across the terminals Current droop during Pulse Simmer current a a ee Current setting input Internal Poti 0 2 V external 100 A V PLB 20 Se ee ee See page 8 for information about the useful operating range Current settling time lt 100 ms full scale Pic LAS FOCUSSING POWER TO THE POINT Operating Range The following diagram shows the operating range regarding pulse current and voltage of the LDP C 200 20 The best performance is achieved with currents above 40 A and compliance voltage between 2 V and 20 V area a Compliance voltages in the range from 4 V to 20 V will result in the best performance Compliance voltages below 4 V yield in longer tail currents above 20 V result in a current droop at the beginning of the pulse Both will not do any harm to the driver A compliance voltage below 1 V is not recommended and may do harm to the laser diode An output curr
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