I have negative experience with silpad from ATX PSU: I used silpads from secondary TO274 schottky's in 600v halfbridge running at ~95khz. Lost two 900v mosfets, few resistors, diodes, PTC, fuse when silpad isolation failed after ca 5 minutes idling.
Got it. Thanks.
Try to start SMPS w/o voltage feedback. Just feed the error amp with a potentiometer hooked up to a Vref and gnd (disconnect comp network form comp pin, connect comp pin to err amp inv input), add a 0.1...1u ceramic cap to error amp input and gnd (place it very close to the 3525)
Tested it today.
Without ANY feedback the SMPS goes full voltage the transformer can provide and load shines (of course). There is no any noise in this mode. As in manual mode with external circuit that drives GDT.
As for potentiometer I did not understand fully. I rebuilt circuit as shown on image, but:
- Below 0,7V between NI and GND the IC just shutdowns.
- Between 0,7 and 3,3V it just works full duty cycle.
- Above 3,3V I hear very similar hiss and crackle from transformer.
That's strange, I checked circuit, that's against simulation did show.
My control originally looks like that I attached.