Help identifying LED Driver IC

[lmagalhaes]

Hey there,

I have some LED power supplies that I want to debug to learn a bit more, but I can't find the driver IC datasheet anywhere. The IC is a 6 pin SOT-23 like with "CB879" marking on top. I have been searching mouser for drivers similar, but most of the drivers I see are boost converters. This one is rated for 60-90Vac in 40-55VDC out.

I have some power supplies that hiccup after 63V and others that are working just fine. I probed the gate of the output MOSFET, on the ones that are working fine, the frequency is constantly changing but the duty cycle stays fairly the same across the 60V~90V input voltage, but on the ones that hiccup, the duty cycle is very close to 100% right at the 60V input voltage and then, when the output starts flashing, the gate goes from the normal behaviour to a much lower frequency with a very small duty cycle. Going back to the 62V at the input stops the flashing completely.

[gamalot]

https://pdf1.alldatasheet.es/datasheet-pdf/view/1133451/FEELING/FP7175LR-G1.html

[xavier60]

It might be useful to be aware of this Supertex part, now Microchip.
https://ww1.microchip.com/downloads/en/DeviceDoc/20005588A.pdf
Not a drop in replacement but functionally the same.
I would sometimes rather get new boards made using Microchip parts instead of trying to source the originals.

[lmagalhaes]

You're a life saver gamalot ! Could figure out that what was faulty was this IC ... replacing the IC with a known good one solved the hiccups, other boards that were overheating and other problems...