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Linux/TPS65911: How to Power off on TPS65911

Sriram V
Intellectual 955 points
Part Number: TPS65911
Other Parts Discussed in Thread: TPS65910

Tool/software: Linux

Hello,

I am using a TPS65911 PMIC chip connected to a DM8147 chip. Unfortunately, We have not connected the following pins to the processor PWRON and PWRDN pins.

We are using the same design as the TI8148 Centaurus EVM.

How can Linux "poweroff/showdown" the PMIC when these pins are connected to the processor. is this the recommended method of powering off.

Also, I wanted to check how does the Linux PMIC driver poweroff the PMIC during Linux shutdown routine (when using Linux "poweroff" command) on Centuaurus or other designs when the PWRON and PWRDN

pins are not connected to the Processor. I think they may configure the PMIC using I2C, however i could not find any code related to it. Could you please point me to the right driver sources which does that.

Regards,

Sriram

  • 0
    TI__Genius 16410 points
    Hi Sriram,

    From a device perspective, you need to set DEVCTRL_REG.DEV_OFF=1 to turn the device off. I found that TPS65911 uses the same driver as TPS65910, so you can see the linux code on line 443 here.

    github.com/.../tps65910.c

    Regards,
    Karl
  • 0 in reply to Karl Wallinger
    Intellectual 955 points
    Hi Karl,

    I have verified that DEVCTRL_REG.DEV_OFF=1 is set during the poweroff command. However, I Still see the PMIC turned on. I wanted to find out
    how to indicate to the TPS that it should start powering off the regulators. We have not connected the PWRDN pin or the PWRON pin to the Processor from the PMIC.

    Thanks,
    Sriram
  • 0 in reply to Sriram V
    TI__Genius 16410 points
    Hi Sriram,

    Are you measuring with a scope, or just looking to see if the PMIC is on? Writing DEV_OFF=1 should shut off the PMIC - so if you still see it on, probably something else is telling it to turn back on immediately. This could be if you're writing DEV_ON=1 at the same time, or if PWRHOLD pin is high. On my EVM, I was seeing that the PMIC shut off only for 12ms in this case before turning back on.

    If you want the PMIC to shut off and stay off, please check that PWRHOLD pin is low, and that you're also writing DEV_ON=0.

    Regards,
    Karl