Good idea, thanks!
You can take a look at the teardown pics including IC's
here.
No question about what the obvious culprit is: Silicon Labs USB-UART chip CP2102. It makes sense, magic smoke occured on (a bit after) connecting the device to my Mac.
A bit better question is: why? I can not imagine my Mac giving out unstable voltages or current surges just out of the blue. Must be the device itself. As I complained initally in the OP, unit seemed faulty from the beginning. Now I'm thinking if the USB chip could be the root cause or just blew as a consequence of something else.
Of course, I'll try to find and replace the chip first. And try to reproduce the problem second. I have no experience with CP2102. I should dig into datasheets about which versions of the chip is used here (DCLOX4). But maybe somebody can advice on this? Mouser
offers 3 chips in the QFN-28 package.
NB One thing bothers me a bit. The PCB seem to be the same for all MS651x models. See model descriptions
here and
here. I have bought (
or at least was buying...) the most advanced, MS6514 model. Why not all the components are deployed? For example, has U9 to do something with other way of power management for a simpler model?. Or, why no diodes on temperature inputs? Can it be so that it is some copunterfeit unit? From the engineering quality it certainly does not seem so...