Flyback Controller IC identification

Question

I am trying to identify the ICs used in a AC to DC step down flyback controller circuit. The circuit includes two ICs labeled as 636O56 440Ap and 631O46 068At. The package size is SOT-23 6. However, when I search for these ICs by name, I cannot find any components that exactly match these numbers, nor do their circuits seem to match other potential ICs I've come across. I've attached images of the circuit and the ICs for reference. How can I accurately identify these ICs? Any insights or suggestions on how to proceed would be greatly appreciated.

Answer 1

The second one is probably an On-Bright OB3636A flyback controller. I found it by searching SOT23-6 "636" marking

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The first one is more difficult. It's likely that it's an On-Bright OB3631 which seems to be a PFC controller. The only reference to the existence of this chip that I could find, however, is this post on the TI forums which has a schematic attached. There is nothing about it on the official On-Bright website.

Answer 2

The 631 may be an OB2263 (a PFC controller, as nanash suggests). There is more than one supplier with different markings, some of which resemble yours.

Your hand-drawn schematic appears to be incorrect - pin 4 is shown as going to a resistor and diode whereas it clearly goes to a capacitor in your photograph. Maybe you swapped 4 & 6?

Answer 3

OB3631AMP is an OV/UV protector. This description is available on some merchandising web sites.