Need Help Identifying IC

[rfdes]

I am hoping someone may be able to identify the semiconductor shown in the photo.  It appears to be, possibly, an optical isolated thyristor based on how it is used in the circuit.  However, I am not 100% sure.  I've done the SMD marking search using some of the online databases with no luck.  The SMD package is not recognizable, so if anyone knows the official 'name' of the package that would be helpful.

I appreciate your opinions.
Thanks
Jim

[rooppoorali]

Not sure. Looks a bit like this one: http://www.aosmd.com/res/data_sheets/AOZ5019QI.pdf

[rfdes]

Thanks for the input.  The IC you mentioned is actually an SMPS part.  I am certain that my part is a logic controlled opto-isolated thryistor part as it is used to turn on/off AC 24V relays.  It is likely an Asian part and  I'm still looking but am on the verge of throwing in the towel.
Jim

[wraper]

It's made by Monolithic Power Systems, according to marking scheme of their parts, this should be MP5019 but I cannot find such part. Sometimes part number may have additional letters after MP, but MPS website search does not find any part with 5019 number anyway.

[wraper]

Overall MP50xx devices have similar packages and are mostly power switches/current protection devices. I really doubt this part can work with AC. https://www.monolithicpower.com/en/catalogsearch/result/index/?p=2&q=mp50
Also it's certainly not how optoisolators look, they have a large gap between input and output. Not a bunch of terminals all around.

[wraper]

Even though there is no data, MP5019GQV does exist https://www.avnet.com/shop/us/products/mps/mp5019gqv-z-3074457345634952895/

[rfdes]

Even though there is no data, MP5019GQV does exist https://www.avnet.com/shop/us/products/mps/mp5019gqv-z-3074457345634952895/

Well... thanks a bunch.  At least I've got a start.  I also reviewed the MPS website and agree with your assessment that the part matches their marking.

The part is used several times in a Honeywell Programmable thermostat.  I've verified that the part is used as an AC SSR with a digital control input.  I am wondering if this is a custom part made for the thermostat mfg.  I think I will reach out to MPS and ask their support engr for some information.

I appreciate your research. 
Take care -
Jim

[gamalot]

Here are some pictures from Chinese sellers.