I am trying to create 100nS optical pulses using a string of 8 IR LEDs with pulse repetition rate of 120Hz. Initially when I was driving a single LED, I used a transistor circuit. The LED's forward voltage is 1.97V and forward current is 100mA. Hence decided to use a source of 16V. My input trigger circuit with the required pulse width and PRF is working and available.

I got the LIB files from the net for UCC27531 (Driver IC) and TK22E10N1 (N-Channel MOSFET). Using the lib, I created the symbol using LT Spice. Attached is the schematic.

I am NOT able to get output from OUTL of UCC27531. I am making a mistake somewhere. Need advice.

Subbu

 

See

 

Identified an error that my MOSFET connections are wrong. As per LIB file, 1=Drain, 2=Gate and 3=Source. While the data sheet differently

 

hi TVB,
A minor point, you can use n=8 to replace 8 diodes.
E

 

Thank you very much for your help. The circuit works in the simulation mode very well. When I went to actually putting this on the board, I realized that I have UCC27531D from TI and this has OUT only, without OUTL and OUTH. I might have picked up a wrong .lib file. Am I correct in saying that?

 

I just short OUTL and OUTH in the simulation circuit and removed EN. It works.