IC for switching power supply identification.

[asrock70]

I have a power supply for USB, wattage 10 to 20W, 4x USB Port. During a storm, the control IC with an integrated MOSFET burned down.
IC is in DIP8, which is missing pin 7
The IC is wired like this

If I understand correctly
1 Current for starting the circuit
2. Power supply during work from the auxiliary winding of the transformer
3. GND
4. I don't see a possible frequency for the internal clock
5. feedback, connect to transistor collector in PC817 optron
6. Source of intrnal mostet , current mesurement on R1
8. Drain of internal MOSFET
What kind of integrated circuit could it be, you can't read it on the case, the marking probably ends with 6H, but it's just a guess and it's completely missing before that
Thanks

 

[dick_freebird]

I might suggest using some of the distributor parts selectors
online, starting with input voltage and pin count / packaging
to narrow the field. From there you can further discard
"candidates" for pinout detail, "brand fragments" and so on.