We just rebuilt a design with MPM3695-25 & MPM3695-10. It appears that the modules no longer respond to the some of the PMBus manufacture commands like MFR_ID and MFR_MODEL. The previous build last year did respond to the commands. Has something changed on the modules?
Hello,
Nothing should have changed with these modules. Are they on the same I2C line? If so, please ensure the addresses are different between them.
In addition, the MPM3695-25 is NRFND. I would suggest going with the MPM3695-20 if possible.
Best,
Krishan
They are on the same I²C bus with different addresses. I have a whole batch of boards where these modules now NACK for those command where they previously ACK and responded with data. This design was done before the MPM3695-20 was released.
Hello Bill,
Thanks for verifying that they are on the same I2C address with different modules. Since you are seeing a NACK where you previously saw an ACK, it means whatever is receiving that data could be corrupted, have missing parts, or there some sort of mismatch.
Have you looked at the data on an oscilloscope and verified the problem in the sent data that could be causing the NACK to occur?
While this question is considered, you should have gotten an email from MPS regarding localized support regarding this issue. Can you verify this as well?
Best,
Krishan