[CRITICAL HW BUG + FIX] STEVAL SPIN3204 board: maximum motor current not reaching 16A as claimed

[Standa Standa]

PCB layout of STEVAL STSPIN3204 board contais critical bug as explained in attached report which prevents the design to work up to claimed 16Arms. This bug creates extreme radiated emissions (affecting nearby instruments) and prevents the proper function of phase current sensing triggering current limit too early. It could be fixed with simple PCB modification (with cutting knife and soldering iron).

Randomly openning gerbers from other STEVAL SPIN32 boards I have found this exact bug (SPIN3202). This leads me to believe that some of your layouters and/or designers might want to refresh layout guidelines for motor control possibly with focus EMC.

If you are interested my company could offer you personalized seminar/training/hands-on which covers those topics or others from theory through practical application to example of schematic or layout reviews before design freeze.

With best regards

Stanislav

[Jolof.1]

Wow, that's really bad.. But what's most important now is ST to respond to this and correct it, and do a review of other boards to check for the same type of issues.

No one from ST staff have answered this yet!

[Dario CUCCHI · Accepted solution]

Hello Stanislav, thanks for your post and your detailed analysis.

I confirm what you have already explained and the issues introduced with the actual PCB layout.

This was a bad mistake, an oversight not immediately found, and it was propagated on different boards of the family.

Even if people work at their best and with competence, sometimes mistakes occur.

Of course I know this is not a justification and I’m sorry if this cause you some issues.

We will schedule a redesign of these boards to overcome this limitation, improve the overall layout and fix the issue.

Best Regards.

[Standa Standa]

Thanks for the response and confirmation.

With regards to how serious this bug is It would be extremely fair to all owners or people who consider buying it to put a huge red title with warning and issue description and with the step how to fix it to the web page of the product.

You can imagine how many hours it takes to convince yourself that it is not your own mistake, review and validate reference schematic, review layout with colleagues, confirm the crazy finding with measurement, apply fix and validate the results.

Please also inform the layouter and review team that vias have limited current capacity and self heating and that it is not OK to put 4 miniature vias and expect them to carry 16 Arms - again check the "good design" on the last page of the report.

Thank you

[Dario CUCCHI]

Thanks for your clear feedback.

I have already forwarded it to all the people involved, who will take the appropriate corrective actions to fix this problem as soon as possible.

I understand what means spending time in debugging and the effort it required to you.

I apologize for it.