MP8675 chip burns at 3A

After facing many problems with MP4470 stability I redesigned everything with MP8675
according to the datasheet MP8675 can sustain 6A and it has overcurrent and overheat protection but when I gradually increase load current to something close or above 3A chip just burns like a fuse (although external mosfet driver continues to work)

I got chips from aliexpress and the only reason why it is happening I can suspect is that they are defective, engineering samples or counterfeit.
But it is extremely strange that anyone would bother counterfeiting this IC.

How I could fix this issue and where to get known good chips?

Do you have and eval board? That represents sort of the best that can be expected designed by engineers who are experienced with the chip.

What is your Vin? Although it says 42V a little reading of the datasheet might convince you that it will survive momentary excursions to 42V it won’t operate there very well. The datasheet shows a 12 to 3.3 converter chip temp gets to 85C at 6A . Other figures show that 42V efficiency is notably lower than 12V efficiency which means even more heat in the IC. What is you inductor? Is it saturating? I would look for an inductor at least to begin that can take 10A.

Good luck

Hi tadas,

It sounds like your application will require a schematic and layout review with MPS Now to start. Please provide as much company/project information as you can when you submit your request. Once in contact with our FAE team, you will be able to share your schematic, layout, and pictures of the IC.
I would also suggest that you always go through one of our verified sales distributors when purchasing MPS devices. That way we can get them involved with our FAE team when troubleshooting the issue.

Maybe I was too quick to declare that IC burns but at least when I replaced it it just overheats and shuts down but it works again when it cools

@ thanks, I will contact MPS but considering those “verified sales distributors” they don’t have anything to offer.

@ jshannon things changed a little after some more testing but my input voltage is about 30V max and output is 13v. inductor should not be an issue because everything overheats and shuts down at less than half of its saturation current I am using 15uh 7A inductor. power supply is rated for less than 5A

I will check how things work at 12 -> 5v conversion, so see if there can be some issues with loss of efficiency

Hi tadas,

I’m not sure what you meant by this. Did you contact one of these distributors and they did not have immediate inventory? Additionally, contacting MPS Now will give you one-on-one assistance from our FAE team. Overheating tends to be an issue with the layout, but we will learn more after receiving your request. Your issue is also the kind of troubleshooting we like to handle through MPS Now and keep the more general questions on MPS ICs and power conversion theory for the technical forum.