EVBUM2320 - NCP1370 Evaluation Board User`s Manual
Contents
1. 314 valley to 4 valley at high line when the LED driver load goes below 80 of its nominal value A table summarizing the valley transitions can be found in the NCP1370 data sheet 2 Figure 7 67 Valley Operation at 50 Output Current High Line In order to compensate the current variation caused by the propagation delays line feedforward is needed The resistor series with the CS pin R16 adjust the voltage offset on the current sense signal as a function of the input voltage The capacitor on CS pin C8 must be kept small in order to avoid delaying the current sense signal and thus increasing the propagation delays Here a capacitor value of 22 pF was chosen Because of the line feedforward and also for reason inherent to the constant current algorithm the obtained output current is slightly lower than the targeted output current Thus it may be necessary to adjust slightly the sense resistor by decreasing it That s why we added R23 33 Q in parallel of the other four 3 9 Q sense resistors www onsemi com 4 NCP1370BGEVB 255 254 253 252 251 250 249 Output Current mA 248 247 246 245 Input Voltage V dc Figure 8 Output Current Variation for Vi 175 V to 220 V 265 263 261 259 257 255 253 Output Current mA 251 249 247 245 Input Voltage V dc Figure 9 Output Current Variation for Vi 100 V to 200 V Figure 8 and Figure 9 shows th2. EVBUM2320 D
3. long as it is stable DC Ammeter DC Voltmeter LED Test Load Figure 18 Test Connections Connect the high voltage source between inputs and of connector Connect a dc power supply between inputs VCC and of connector Connect a power supply between inputs and 3 of X3 connector Connect the ammeter to LED output of X2 connector and then connect the LED load positive terminal to the ammeter and its negative terminal to the output of X2 connector Functional Test Procedure Set the load at 200 V output Set the input voltage to 162 V dc Measure the output current its value should be within 2 of 250 mA www onsemi com 9 Flyback Inductor Specification ELECTRICAL SPECIFICATIONS D C RESISTANCE D C RESISTANCE D C RESISTANCE NCP1370BGEVB 2056 10kKHz 100m Ls 257 C unless aha ti VALUE 0 027 ohms 20 0 288 ohms 10 0 343 ohms 210 400uH 210 SATURATION CURRENT 1 3 20 rolloff from initial 100 C 1 3 5 5 84410411 10013 Ls DIELECTRIC 1 11 tia 3 5 9410 4000 1 second 1 3 1 1 8 tie 9 10 1 1 196 MAY EXCEEDED WITH SOLDER ONLY PART MUST INSERT FULLY TO SURFACE A IN RECOMMENDED GRID 024 50411 581 LOCATES TER 1 a75 22 DOT LOCATE
4. or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application Buyer shall indemnify and hold SCILLC and its officers employees subsidiaries affiliates and distributors harmless against all claims costs damages and expenses and reasonable attorney fees arising out of directly or indirectly any claim of personal injury or death associated with such unintended or unauthorized use even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part SCILLC is an Equal Opportunity Affirmative Action Employer This literature is subject to all applicable copyright laws and is not for resale in any manner PUBLICATION ORDERING INFORMATION LITERATURE FULFILLMENT American Technical Support 800 282 9855 Toll Free Semiconductor Website www onsemi com Literature Distribution Center for ON Semiconductor USA Canada 19521 E 32nd Pkwy Aurora Colorado 80011 USA Europe Middle East and Africa Technical Support Order Literature http www onsemi com orderlit Phone 303 675 2175 or 800 344 3860 Toll Free USA Canada Phone 421 33 790 2910 Fax 303 675 2176 or 800 344 3867 Toll Free USA Canada Japan Customer Focus Center For additional information please contact your local Email orderlit onsemi com Phone 81 3 5817 1050 Sales Representative
5. 2 V on VCC pin The board has a low profile and its height does not exceed The output current is set to 250 mA by the sense resistors 15 mm R17 R18 R20 R21 and R23 2 1 2 2 1 4 2 P_DIN 120 p DRU_ON SGND 12 470nF 4800 SGND R30 22k D11 R31 47k 10k os MUR16 MUR160 D7 010 4148 4148 R27 10k R25 4k7 R28 25 41 22k R26 22k cya 1nF 4009 SGND SGND GND 06 1 4937 D4 4148 47uF 450U 6 10 GND UBULK 4 1 O X1 2 X1 3 O Figure 2 Evaluation Board wit 200 V 250 mA Output www onsemi com 2 NCP1370BGEVB 0 95 95 95 uT TAD 1 5 X AZZ 928 i AZZ 2 Td 92 854 671 873 i Z E X 0 42 l i 2 1 5 82178004 lt 223 7 BbTb V V eta O 1 0 95 IM 2 4 O A 2 60 NX 9r B9TANN 8a 204 264 N ST ACT 212 2 aN9 9 19007 Ze AGT T YN Yee 686 646 ecu 024 1874 3 8 8015 TO 072 266 90 NAT SUT 69 NOSES ANZY NGE ANT ON AQT sea 122 AZT b
6. NCP1370BGEVB NCP1370 Evaluation Board User s Manual NCP1370 15 a primary side constant current controller It features a built in control algorithm that allows to precisely regulate the output current of a Flyback converter from the primary side This eliminates the need for an opto coupler and associated circuitry The control scheme also support non isolated topology such as Buck Boost and SEPIC The output current regulation is within 2 over a line range of 85 265 V rms The power control uses a Critical Conduction Mode CrM approach with valley switching to optimize efficiency and EMI filtering The controller selects the appropriate valley for operation which keeps the frequency within a tighter range than would normally be possible with simple CrM operation This manual covers the specification testing and construction of the NCP1370 demonstration board The board demonstrates a 50 W LED driver for TV backlighting A dimming circuitry is also provided to show the dimming performances of the NCP1370 The board allows building 2 different power converters 200 V Output Voltage with an Output Current of 250 mA 100 V Output Voltage with an Output Current of 500 mA Specifications The board is designed to meet the specifications of Table 1 Table 1 LED Driver Specifications Description Symbol Value units wasn tinge vee rum ovina vite Output Voltage at which the OVP i
7. S TERM 4 118 187 8 ae 1 299 5 00 5 001 33 00 i 1 035 Lh 26 30 Loi bey L LOT CODE amp DATE CODE 4 L TERM 0 75 FOR REF ONLY 01 he d 8 052 12 PRI 1 32 gt 120 375 06 2 9 BOkHz P see 2504 200 5 9 mi AUK 14 50 22 211 08 RECOMMENDED SIDE PATTERN CUSTOMER TERMINALS 9410 TOGETHER BOARD Figure 19 Flyback Inductor Specification www onsemi com 10 NCP1370BGEVB Bill of Materials Table 2 NCP1370 BILL OF MATERIALS ed Qty Reference Description Value Constraint Footprint Part Number D1 D4 D5 Standard Diode 1N4148 100 V SOD 123 ON Semicondutor MMSD4148 D7 D10 1N4937 Rectifier R7 R8 R11 R12 R19 Resistor 10 5 125 mW SMD0805 Standard Standard R27 R29 R35 R13 R22 220 5 125 mW SMDO0805 R21 R30 0 ne 1 2 Output Connector Through Hole Standard Standard NI gt NIN o 4 gin 2 oll p 5 www onsemi com 11 NCP1370BGEVB References 1 St phanie Cannenterre Application note AND9131 D Designing a LED Driver
8. e output current measured Looking at Figure 8 where the LED voltage is varied from when the input voltage is varied from 120 V dc to 375 V dc 175 V to 220 V roughly 200 V 11 we can calculate the for different LED string voltages A Chroma electronic load mean output current value and the current regulation in LED mode is used to emulate the LED string voltage variation www onsemi com 5 NCP1370BGEVB The mean output current is calculated by considering the maximum and the minimum value measured over the output voltage and the input voltage range lout Max lout min louT Mean 2 eq 2 _ 253 8 246 8 2 250 3 mA The output current regulation is then calculated as follows Al OUT _ 400 OUT Max OUT Mean eq 3 lout louT Mean _ 253 8 2503 1 250 3 The output current regulation is thus 1 4 for a LED string voltage varying from 175 V to 220 V and for the input voltage varying from 120 V dc to 375 V dc Figure 9 portrays the current variation when the LED voltage is decreased down to 100 V the nominal voltage being 200 V in order to simulate the case where several LEDs are shorted We can see that the current regulation is still good We have 254 6 mA 2 5 lout2 Max lout2 min louT2 Mean 2 eq 4 _ 260 9 248 3 202546 mA Al lout2 mMax 7 loute m OUT2 _ 100 2 Max 2 Mean eq 5 louT2 Mean 260 9 254 qoo 254 6 Dimming A circuit made of the o
9. ed 53 5 gt AINENA O 1 2 O T TX Figure 3 Evaluation Board wit 100 V 500 mA Output www onsemi com NCP1370BGEVB Valley Switching and Valley Lockout The 1370 implements current mode quasi resonant architecture which optimizes the efficiency over a wide load range by turning on the MOSFET when its drain source voltage 15 minimal valley Depending on the power supply design it is possible to achieve almost zero voltage switching as shown by Figure 4 When the light is dimmed the controller selects a following valley to reduce the switching frequency and Figure 4 151 Valley Operation at Low Line Full Load Figure 6 47 Valley Operation at 50 Nominal Output Current Low Line Output Current Regulation The output current value is set by the sense resistor RsENsE formed by R17 R18 R20 R21 and R23 on the board The sense resistor value can be calculated with VREF Rsense eq 1 2 Nsp lout Where Nsp is the transformer turn ratio secondary turns divided by primary turns 15 the targeted output current Vref 15 the reference voltage for constant current regulation keep the switching losses low For stable operation the valley at which the MOSFET is switch on remains locked until the light demand is changed Practically the NCP1370 transitions from quasi resonant operation to the 2nd valley at low line and from
10. harged down to O V after the 1 second timer has elapsed thanks to the dummy output resistor R32 Figure 14 Vour Waveform in Case of Open LED In order to decrease the maximum voltage reached on the output connector in case no LEDs are connected to board the circuit shown Figure 16 can be used The maximum D3 1N4148 R103 VIN 3 9k 2N3904 Figure 16 Alternative Circuit for OVP on VIN Pin As soon as the zener diode starts conducting the transistor Q3 is turned on and then bias Q4 which allow pulling the VIN pin high above 5 V immediately In this case we need Figure 15 Waveform in Case of Open LED after the OVP Timer Has Elapsed voltage reached on the board when no LED was connected was 300 V with this circuit Figure 17 Open LED with New OVP Circuit on VIN Pin to use an 18 V zener diode instead of a 16 V to avoid triggering the protection during the normal operating range www onsemi com 8 NCP1370BGEVB Test Procedure Equipment Needed High voltage source 100 to 375 V minimum 500 W capability Two dc sources 30 V DC Voltmeter 300 V dc minimum 0 1 accuracy or better DC Source 5 V Setpoint High Voltage NCP1370EVB DC Source DC Source 14 V Setpoint DC Ammeter 1 A dc minimum 0 1 accuracy better LED load between 175 to 215 V at 250 mA A constant voltage Electronic load is an acceptable substitute as
11. olled by the DIM pin and the measured a function of the PWM dimming signal duty ratio The tests current matches the expected value even at low duty ratio were made at 162 V dc We can observe that the output dimming thanks to the soft stop 200 lt 150 L 5 5 100 Q 5 50 0 Dimming Duty Ratio Figure 12 Output Current vs PWM Dimming Duty Ratio 14 12 10 lt z 8 5 6 5 Q 5 O 4 2 0 Dimming Duty Ratio Figure 13 Output Current Variation for PWM Dimming Duty Ration between 1 to 5 www onsemi com 7 NCP1370BGEVB Over Voltage Protection Open LED Protection By monitoring the auxiliary winding voltage through D3 D4 R22 and C6 we have an image of the output voltage By connecting a zener diode from C6 to the VIN pin we can trigger the over voltage protection OVP When pin VIN voltage exceeds 5 the controller stops and restarts switching after 1 second In order to reach 5 V on VIN pin a current of approximately 900 uA must be injected inside the pin by the zener diode We chose a 16 V zener diode As the OVP threshold is 5 V the comparator will trigger when the voltage on capacitor C6 exceeds 16 V 5 V 0 6 V 21 6 V 0 6 V being the forward voltage drop of diode D1 Figure 14 and Figure 15 show the output voltage waveform in case of open LED The maximum output voltage is 345 V On Figure 15 we can see that the output capacitor is disc
12. pto coupler OC1 the transistor Q2 and some resistors is used to send the digital dimming signal from the secondary side to the DIM pin of the controller on the primary side By default at start up the controller 15 in OFF mode In OFF mode the controller consumes less than 50 uA The controller leaves the OFF mode when Vcc gt and VDM gt During normal operation the OFF mode is entered when Stays below for 4 seconds Back to the evaluation board in order to start a voltage of at least 3 3 V must be applied on connector For digital or PWM dimming apply 3 3 V on DRV_ON and apply a square signal varying between 5 V to with a 200 Hz frequency on P_DIM By varying the duty cycle of this signal the output current will also vary Figure 10 shows the output voltage and current when dimming with 50 duty cycle Figure 11 shows the dimming pin voltage and the drain voltage in addition to the output current when the dimming signal has a duty cycle of 10 The resistors R12 and R11 with the capacitor C4 adds in an extra soft stop which delays the LED turn off and compensates the internal soft start of the NCP1370 and also the time needed for the output voltage to be high enough to turn on the LED Figure 10 50 PWM Dimming Figure 11 10 PWM Dimming www onsemi com 6 NCP1370BGEVB Figure 12 and Figure 13 show the output current as current is nicely contr
13. s Te OVP V Activated Output Current Nominal 2350 Input Voltage for Brown In Switching Frequency at POUT 100 kHz and VIN Min Description of the Board The board has been designed using the method described in the application note AND9131 D 1 Figure 2 shows the schematic of the 200 V 250 mA LED driver which is the default board version Figure 3 portrays the schematic of the 100 V 500 mA LED driver The resistor R12 connected to pin 1 ILIM of the controller sets the peak current limit threshold to 2 4 V A resistor divided formed by R34 and R35 is used to limit the voltage and current in ZCD pin R16 is the line feedforward resistor that compensates the output current variation caused by the propagation delays Semiconductor Components Industries LLC 2015 1 October 2015 Rev 0 ON Semiconductor www onsemi com EVAL BOARD USER S MANUAL Top View Bottom View Figure 1 NCP1370 Evaluation Board Publication Order Number EVBUM2320 D NCP1370BGEVB R1 R3 R5 R7 R8 and R10 are the brown out resistors R23 is used to adjust the output current exactly to 250 mA which have been calculated to start operating at A small output capacitor of 470 nF is used in order to have Vin 110 V a square output current waveform when PWM dimming is The controller is supplied by an external power supply In used order to start the controller needs at least 1
14. with the NCL30080 8 1 82 83 2 Data Sheet NCP1370 D ON Semiconductor and the W are registered trademarks of Semiconductor Components Industries LLC SCILLC or its subsidiaries in the United States and or other countries SCILLC owns the rights to a number of patents trademarks copyrights trade secrets and other intellectual property A listing of SCILLC s product patent coverage may be accessed at www onsemi com site pdf Patent Marking pdf SCILLC reserves the right to make changes without further notice to any products herein SCILLC makes no warranty representation or guarantee regarding the suitability of its products for any particular purpose nor does SCILLC assume any liability arising out of the application or use of any product or circuit and specifically disclaims any and all liability including without limitation special consequential or incidental damages Typical parameters which may be provided in SCILLC data sheets and or specifications can and do vary in different applications and actual performance may vary over time All operating parameters including Typicals must be validated for each customer application by customer s technical experts SCILLC does not convey any license under its patent rights nor the rights of others SCILLC products are not designed intended or authorized for use as components in systems intended for surgical implant into the body or other applications intended to support or sustain life
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