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TPS65910 PWRHOLD's connection

Jiansheng Liu
Intellectual 310 points

Hi,

I am getting confused about PWRHOLD's connection. As the datasheet description it should be connected to VIO to maintain power rails output (that is what I am doing), however the link below about a reference design pulls up this pin to VTRC instead:

http://designsomething.org/craneboard/w/hardware/default.aspx

Since VRTC is an always-ON rail it will never get chance to have PWRHOLD back to zero, how the power-off process could be implemented (software controlled)?

The datasheet also confused about its power domain: on page 3, it is described as "PWRHOLD IO is supplied from VDDIO". On the page 37 however table 11 gives that PWRHOLD supplies is from VRTC/DGND. So which one is right?

I have problem to see PWRHOLD back to zero (connected to VDDIO) after DEV_OFF bit is set. VDDIO only falls down to about 0.8V about 3.5mS, and this residential voltage triggered another power on process so PMIC is powered on again. What is the possible root cause?

Someone help please!

Thanks

Jiansheng 

  • 0
    TI__Intellectual 2090 points

    Hi,

    I understand your confusion in fact PWRHOLD can be connected to VRTC or VDDIO or VCC7.
    Regarding your configuration, it seems that you don't realy need PWRHOLD. It means that you are looking for a way to connect it.
    The best way to connect it in your case will be to connect it to NRESPWON. Meaning that PWRHOLD will be maintain automatically at the end of POWERUP seq.

     Regarding, PWRHOLD has an internal pull down and it should bring back VDDIO to 0. I understand that you have a residential voltage but I don't understand why.

    Please refer only to TI website to find datasheet
    http://www.ti.com/product/tps65910