Chip identification? Flyback controller that uses BJT?

[mikedoubleu]

Hello all,

I'm wondering if anyone can help me identify a little 6 pin chip.  It's the controller chip for a small flyback SMPS.  I'm fairly new to these things, but it seems notable that the switching transistor is a BJT (SD13003) as opposed to a MOSFET.  I'm hoping that can help me track down the part number, but I'm having a hard time so far. 

The marking is 20F09, and also 57A on another line. 

Also, there's no feedback from the secondary here, not sure if that helps identify a category to search in...

Thanks for any help or advice!

[T3sl4co1l]

TI makes one, https://www.ti.com/lit/ds/symlink/ucc28722.pdf but I'd bet you have a Chinese version.

Tim

[mikedoubleu]

Ah shoot, close but no cigar.  Pinout a bit different.

Thanks for that though, I'll keep digging. 

[mikedoubleu]

SOLVED!  It is OB2520.