It used to be a TOP222 controller IC for small 'flyback' switched mode power supplies but that one is most certainly absolutely dead!
It looks like either a 3 pin transistor or a small 8-pin IC (same device, different package) but it actually has a high voltage MOSFET and control circuit inside it. Typically used in small 'wall wart' power supplies because of their low cost. Be very careful if you work on the circuitry it came from as they generally have several hundred volts across them and are not isolated from the incoming AC power.
22283a is a date or production lot code. TOP222Y or TOP222YN (Pb-free) does fully specify the part.
There's effectively no replacement, except possibly for similar Topswitch parts from Powerint.
A combination of a discrete MOSFET and a standard current mode controller IC like UC3842 might theoretically work but needs many additional parts and will hardly fit the original circuit.
So
I replaced the part and now the power supply turns on but outputs a constant 0.6v (it is a 3-15v 40amp variable output power supply) what else could be damaged to cause this symptom?
circled in red is the original area the offline PWM switch was located
cheers!