TPS650864: PMIC o/ps are not stable

prema R

Part Number: TPS650864

Tool/software:

We are using PMIC TPS6508641 to power Zynq ultrascale+ XQZU19EG-2FFQB1517I.

We are using 6V to power the PMIC. The PMIC o/ps are not stable. The below is the capture at buck1 output 5V. and its feedback signal FBVOUT1.

5V output:

FBVOUT1:

Buck2 o/p:

We removed R32(please refer schematics below) and checked. Then pmic output 5V is ok but still feedback is not ok

Below is our schematic:

Please note we are providing 6V to both PMIC Vsys and U5 drain. Also we provided external LC components to LX5 and have disconnected FB5 from gnd and connected to a o/p cap.

8 months ago

0 Sathish Vallamkonda 8 months ago

TI__Expert 6075 points

Hi Prema,

10ms re-try indicates that one of default power rail is having issues with not able to come up.

Please refer to the below FAQ and towards the end there is list of outputs to check in the order. Please check all the default rails are coming up wrt to CTL pins and check which one is causing the shutdown. There is a link to another E2E post within that.

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/992402/faq-tps650864-regulator-is-shutting-down-or-measuring-x-lower-than-expected---what-is-the-cause/3665210?tisearch=e2e-sitesearch&keymatch=TPS650864%252520faq#3665210

Sathish

Power management

Power management forum

TPS650864: PMIC o/ps are not stable