UVLO error after enabling boost regulator of MAX98390

Hello AliRazavi,

I do not know the answer since I am not the expert in this part. I have notified the expert and they should get back to you soon. Meanwhile, it might be handy to see the complete register writes you are sending to the part to set it up? It will save time so the expert does not have to ask you and then wait for you to reply. 

Thanks

Dave T

Hello AliRazavi,

A couple of suggestions to track down this Boost UVLO issue:

1) Confirm that the issue is not present when using the same register program settings for the MAX98390 on the MAX98390 Evaluation Kit.

2) Check that the traces used to short PGND to AGND are very short. Ideally AGND should have a single point connection directly to PGND, underneath the device's pins. The ferrite bead FB1 should not be necessary.

2b) If the ferrite bead FB1 is needed, be sure that its resistance is very low. Be sure the traces for AGND and PGND to FB1 are extremely short to reduce any unwanted inductance and resistance.

3) Is the current draw from 3v3 high when the Boost UVLO occurs? If this is the case, then there may be something limiting the boost from coming up, like if the boost peak inductor current is set too low, or the output load too high.

4) Check that the 3v3 supply is stiff and does not droop when the boost starts up.

5) Another possibility is layout parasitics, please reference the MAX98390 Evaluation System data sheet for an optimized layout, MAX98390C/D Evaluation System - Evaluates: MAX98390C/D (analog.com). 

 Best regards,

Andrew