AnsweredAssumed Answered

100 W LED Driver [ LT3791 ] - Design assistance needed

Question asked by roboticist on Apr 13, 2018
Latest reply on Apr 23, 2018 by lallison


I am trying to power up 100 W LED using LT3791 Buck / Boost LED Driver, but it seems like there is something wrong with it. Let me explain what I have done:

- I have designed the schematic, shown below:


- I have desinged PCB, shown below:

* top & bottom*






The only difference is that I have used different MOSFET ( instead of RENESAS RJK0651DPB and RENESAS RJK0451DPB I have used4 transistors PSMN7R5-60YLX ). 


The Driver is designed to power up CLU038-1210C4-DTE LED. 


I have measured EN/UVLO, OVLO ( I have tried different combinations of values et cetera ), PWM is working - PWMOUT is similar to PWM, the prototype was powered via power supply ( max. current 10 A ). 


The most important thing is that the circuit is working from approximately 30 V DC ( works at BUCK / BOOST and BUCK region). I have also tried it with big capactior ( 22 000 uF ) at input. I have checked simplified model in LTSpice recommended by producer. Power Ground is connected via single point to GND ( 0R resistor ). 


I would be greatful if someone can help me.


Best regards,