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TPS65987D: Failed to drive GPIO low

Antony Lin
Genius 13480 points
Part Number: TPS65987D
Other Parts Discussed in Thread: TPS65987

Hi,

For this docking project using TPS65987DDH, GPIO1 is configured as below.

This GPIO is connected from TPS65987 to a MCU GPIO directly without external pull.  The default level is high as seen from above setting, and we tried to send GPsl/GPsh to change the output level.

But, when we send GPsl to drive it low but found it failed.  It can work for either condition as below.

  1. Add a 1Mohm resistor pull-down resistor on board.
  2. Probe this signal from a scope (P6139B/Tektronix, 10Mohm, 8pF).

It seems a pull-down resistor on board is helpful, but we can't change the HW design now.  We tried to disable "Internal pull up enable" setting but not help.  Please support to provide your input.

Thanks!

Antony

  • 0
    TI__Genius 12700 points

    Hi Antony,

    I have assigned this issue to an expert who will get back to you shortly.

    Thank you,

    Hari

  • 0
    TI__Mastermind 29755 points

    Hi Antony,

    I tested on the EVM and it works using GPsl or GPsh in either open drain with internal pull up or push pull configuration.

    You can use the apps GUI and put in debug mode, check under GPIO status register (0x72) the GPIO direction (1-output, 0-input) and the data itself when you send GPsh or GPsl.

    My suggestion:

    • check the direction of the GPIO, maybe MCU is not set it correctly.
    • check if the GPIO is enable; if initial value is '1' it's enabled already.
    • check the data read back.

    Regards,

    Peter