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CCS/TPS65381A-Q1: TPS65381A VDD5 pin

CHATBOT
Prodigy 210 points
Part Number: TPS65381A-Q1

Tool/software: Code Composer Studio

Hello,

 

I'm using TPS65381A as companion power mangement IC for TMS570.

 

Problem is that operational amplifier around analog input of the TMS570 is powered by another 5V.

 

So, to protect analog input pin of TMS570,I should power off the 5V before TPS65381A shuts down.

 

But it is not easy. So, I am trying to place diode between 5V generated by TPS65381A and 5V.

 

But I worry if VDD5 pin is damaged or not in case 5V generated by TPS65381 shuts down earlier than 5V.

 

Please tell if VDD5 will be damaged or not by anther 5V.

 

Thanks in advance and best regard

   

  

  • 0
    TI__Genius 9380 points

    CHATBOT,

      The VDD5 is an LDO. It also feeds other circuits internally. You can not feed 5V backwards into the VDD5 pin especially if the IC is powered off as it will damage the IC.  Consider dual diodes that will protect both 5V rails, like an OR circuit. Schottky diodes will have the lowest forward voltage drop for this application.

    I hope this helps.

  • 0 in reply to Gordon Varney
    Prodigy 210 points

    Thanks for your quick Varney-san.

    I undestood voltage on VDD5 from other source is not good.

    I will use another LDO to supply 5V to opamp.

    Best regards.