Mean Well HDR-150

[Vovk_Z]

I got one more unknown 6-pin chip. It is situated in the secondary side of a power supply. I guess it is an over voltage protection circuit (?).  It looks like it is an opamp (possibly with voltage reference).
It's code is A5195P. Have anybody some clue about this part?

[fzabkar]

I tried to find some Mean Well PSU circuit diagrams.

FWIW, I found this one:

https://elektrotanya.com/mean-well_psp500-48_sch.jpg/download.html

There is an M51957B chip on the secondary side:

https://docs.rs-online.com/4d41/0900766b80c2db9a.pdf (datasheet)

This is a reset supervisor IC with different pinouts and packages, so the similar part number may be a pure coincidence. You might like to take the 8-pin part and ignore the NC pins, and then compare it against your 6-pin part ...

That said, this spec sheet does refer to OVP ...

https://www.meanwell-bg.com/files/M2020/HDR/HDR-150-spec.pdf

I hope I haven't introduced a red herring.

[Vovk_Z]

I accidentally found that there is whole AP43XX opamp family. So it could be AP4312, AP4313 or AP4320 (SOT-23-6). I haven't checked it yet, but I now see AP431X family is used in other Mean Well power supplies. 
I mean SO-8 AP4310A is used a lot (this is opamp + precision voltage source), so unknown SOT-23-6 chip can possibly be from AP43XX series too. I'll investigate it next days.

Upd.: Pinout says it can be AP4320.
Upd.2: Datasheet says AP4320 has two options, A and B, 30 mV and 50 mV current sense protection. So, I ordered both, will see what suits better. Power supply under repair has 0.01 R shunt and is 3 A rated, so 30 mV option seems a bit low but 50 mV option seems a bit high.

[Vovk_Z]

Yes, A5195P (or A5190F) code is AP4320AK or AP4320BK, both works (chips arrived today). The only difference between -AK and -BK is current protection setting, and it is about 3.7-3.8 A with AP4320AK and it is about 4.7-4.8 A with AP4320BK. Both settings are fine for HDR-150-48.
PCB revision is HDR-150-R3.

[p.larner]

did that fix it?.

[Vovk_Z]

did that fix it?.

Yes. I had symptoms that clearly showed broken opamp (too high output voltage, optocouplers were replaced and nothing else seems to be broken). After its replacement the power supply works fine.