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TPS6593-Q1: LDO1 and LDO2 showing 0V unexpectedly

peter bradbury
Prodigy 40 points
Part Number: TPS6593-Q1
Other Parts Discussed in Thread: AM62A74

Tool/software:

Hello, we are using the TPS65931211RWERQ1 on a custom board to power the AM62A74. This is the second rev of the board and the first rev worked just fine, second rev is working just fine with the exception of this problem on one board. 

I have found that LDO1 and LDO2 which supply power to the VDDSH_SDIO and VPP_1V8 rails respectively, are showing 0V when we brought it up. I have checked for shorts while powered off and there are none. All other bucks and LDO's are showing correct voltage. There are 2.2uF caps on the output of each. 3.3V VIN for the PMIC. This is a one off problem. 

The schematic was largely (98%+) copied from the AM62A74 eval kit. 

  • 0
    TI__Mastermind 20399 points

    Hello Peter,

    Between the two board builds has the software changed at all?

    The LDO1 & LDO2 are enabled via GPIOs like below, my only conclusion being that if everything else is powering up as previous and without error with the exception of these two rails then I would like on the processor side hardware and if no differences are found there, look at the software to see if the PINMUX or GPIO toggles have been changed.

    Thank you for posting the schematic you have BTW, I don't see any influence on the PMIC from the GPIOs, so please do the above, hope that helps!

    Here's the User's Guide on the PMIC BTW

    BR,

    Nicholas McNamara