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TPS650864: Unused LDOA2 ve LDOA3

doner_t
Intellectual 645 points
Part Number: TPS650864

Tool/software:

Hello,

I will not use LDOA2 ve LDOA3 in TPS6508640 PMIC. Is it enough to tie pin PVINLDOA2_A3 to GND and leave LDOA2 & LDOA3 outs floating?  or is it still necessary to populate output capacitors LDOA2 & LDOA3 out pins?

Best Regards,

  • 0
    TI__Expert 6245 points

    Hi,

    Thank you for reaching out on E2E.

    LDOA2 and LDOA3 are part of the power up sequence, so PMIC wont be able to complete the power up sequence if LDOs didn't come up during the power up sequence.

    I will leave populate the output caps and if the board is in design phase, i would even add a place holder for bleeder resistor just incase to add a small load if needed.

    Sathish 

  • 0 in reply to Sathish Vallamkonda
    Intellectual 645 points

    Hi 

    Thank you for your quick reply. 

    Input of LDOA2 & LDOA3 (PVINLDOA2_A3) are already grounded. Thus, am I not actually disabling these two LDOs? Why do I need still add capacitors outputs? It doesn't make sense to me. Is it a general rule for LDOs? Could a no-load situation cause problems for LDOs?

    POWER FAULT MASKED of LDOA2 & LDOA3 are "yes" by default in the Table 8-3 of datasheet. So, does this mean that if LDOA2 & LDOA3 are failed, power-up sequence will not be affected? 

    Best Regards,

  • +1 in reply to doner_t
    TI__Expert 6245 points

    Hi,

    Sorry for the confusion. I went back and confirmed both those LDOs are disabled in TPS6508640. It makes sense to ground the inputs.

    When LDOs are disabled you can leave the output pins floating and no need to populate both input and output caps.

    Sathish