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TPS65910: PWRHOLD at startup of PMIC (TPS65910AA1RSL(R))

Conor
Guru 10090 points
Part Number: TPS65910
Other Parts Discussed in Thread: AM3352, AM3517, AM3505

Hi,

I am trying to activate the PMIC by connecting a push button switch to the PWRON terminal, but the moment I release the switch, the PMIC turns off.

The datasheet states that the ON state is maintained for 1s (tdbPWRONF + tdSONT + tdONPWHOOLD) after detecting PWRON.


Therefore, I was thinking of setting PWRHOLD to H within 1 second after detecting PWRON to maintain the power supply, but tdONPWHOOLD was not secured for about 1 second.

１）Could you please let me know the possible factors?

２）This is related to question 1). I think that not using the 32K clock of AM3352 affects 1).

- Figure.1 of TPS65910Ax User's Guide for AM335x Processors


- AM335x Starter Kit (SK) Schematic

Both OSC32KIN are Lo fixed and BOOT=10.
The datasheet says that if BOOT=00, the internal oscillator can be used, but both are BOOT=10.

Also, the TPS65910X data sheet states that if BOOT=00, the sequence will match the AM3517 and AM3505 (6.3.2 Switch-On/-Off Sequences).

・How can I secure tdONPWHOOLD 1 second with AM3352?
・ Should I set BOOT[1:0]=10 for AM3352?

Thanks,

Eevee

  • 0
    TI__Intellectual 2051 points

    Howdy. The device expert for this part is currently unavailable until 2/13. I'll look into this thread sometime this week, so please expect a delayed response.

    Best,

    David Martinez

  • 0 in reply to David Martinez
    Guru 10090 points

    Hi, David

    I understood. We are waiting for your reply.

    Thanks,

    Eevee

  • 0 in reply to Conor
    TI__Mastermind 41481 points

    Hi Eevee,

      My PTO was cancelled, so I can support you now.

      Please make sure you either set the "DEV_ON control" bit to "1" or the "PWRHOLD" pin to high BEFORE the "TdOINT1" one second delay expired.

      Your scope capture doesn't show the "PWRHOLD" pin is set to high at all.

      To be safe, you can tie the "PWRHOLD" pin to high even before push the PWRON button.

    Thanks!

    Phil 

  • 0 in reply to Phil Yi40
    Guru 10090 points

    Hi, Phil

    Thank you for your prompt reply. It seems that what we want to do is not conveyed correctly.

    [What I want to achieve]
    Press "SUBP_SW" on the board below to turn on the power of the board. After that, I want to start the PMIC by setting PWRHOLD to High with the GPIO of the CPU within 1 second from the start of pressing SUBP_SW.

    The power is turned off the moment the switch is released, even though tdbPWRONF + tdSONT + tdONPWHOLD (about 1 second) has not passed since the push switch was pressed to turn on the board.

    Thanks,

    Eevee

  • 0 in reply to Conor
    TI__Mastermind 41481 points

    Hi Eevee,

       The 1 second is not from the moment of the switch is released; it's from the moment of the switch is pushed. 

       Can you also try to set the "DEV_ON control" bit to "1"? just in case the connection of PWRHOLD pin to the GPIO of the CPU has issue. 

    Thanks!
    Phil

  • 0 in reply to Phil Yi40
    Guru 10090 points

    Hi, Phil

    Phil Yi40 said:
     The 1 second is not from the moment of the switch is released; it's from the moment of the switch is pushed. 

    I understand what you are saying. As far as the waveform below is concerned, the power is turned off before 1 second has passed since the switch was pressed.

    Thanks,

    Eevee

  • 0 in reply to Conor
    TI__Mastermind 41481 points

    Hi Eevee,

       The tdOINT has the 1 second as typical value; it could have range from 0.5S to 1.5S. 

       Can you also try to set the "DEV_ON control" bit to "1"? just in case the connection of PWRHOLD pin to the GPIO of the CPU has issue.

    Thanks!

    Phil