AD5421BREZ changed? (AD5421BREZS1)

A little more information.  I'm driving it with an ADum5411.  In the failing units, the applied VLOOP is good, but the reported VLOOP is very low (1 to 3V).  I am getting the undervoltage faults from the failing units.  I checked each pin with a voltmeter and compared good to bad - there really is no discernable difference.  I did notice that the IO_VDD pin was fluctuating in both units and remembered that I'm disabling the ADum5411 after I set the DAC.  I stopped disabling the ADum5411, but the failing unit is still failing.

Hi KyLongley ,

Thank you for providing additional information. Before moving further I would like to confirm some details about  AD5421BREZS1. Kindly confirm where you ordered the variant, where and what type of branding you saw on the units you have on hand. It would be much appreciated if you could provide a picture displaying the "S1" branding. 

Best Regards,

Den

Hi KyLongley ,

Thank you for providing additional information. Before moving further I would like to confirm some details about  AD5421BREZS1. Kindly confirm where you ordered the variant, where and what type of branding you saw on the units you have on hand. It would be much appreciated if you could provide a picture displaying the "S1" branding. 

Best Regards,

Den

The AD5421BREZ is the working board.  The other three with S1, S2, and S3 suffixes are all giving me problems.  They were purchased by our contract manufacturer through Digikey.

Hi KyLongley ,

Thanks for more details and images, we'll investigate this further and get back to you.

Best Regards,

Den

Hi KyLongley ,

Again, thanks for bringing this to our attention, we are still investigating this matter. In order to continue our discussion about part markings, since it is not advisable to discuss such topic in our community forum, we'll be reaching out to you offline via the email that you have provided. Thank you for your patience and apologies to the inconvenience caused.

Best Regards,

Den

Den,

That would be great.  But when do I expect someone to reach out?  This could stop production and I need to know what is going on.

Hi KyLongley ,

Thanks for your patience. I have sent an email and we can continue our conversation offline. Thanks

Best Regards,

Den