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TCAL9539: GPIO Open Drain

Fabio Gou
Expert 4445 points
Part Number: TCAL9539

The customer want to configurate GPIO as open drain.

But I see it is push-pull design structure.

So whether it is available?

  • Guru 316920 points

    The description "push-pull design structure" means that the pin is capable of pulling high. But when a port is configured for open-drain I/O by setting its bit in the output port configuration register (4F), then its pins do not actually pull high.

  • TI__Mastermind 47748 points

    Hi Fabio,

    Clemens answered your question correctly. The pin description states that the design is push-pull architecture, but this doesn't mean that the push-pull design can be configured for open-drain by disabling the pull-up FET internal to the device. 

    Open-drain mode can be configured via register 0x4F. 

    Regards,

    Tyler

  • in reply to Tyler Townsend
    TI__Expert 4445 points

    Push-pull is set to registers46/47(Enable), 48/49(selection)
    How can we control the behavior of each pin after setting it to open drain through 4F?

    I did not see the open drain selection command from the datasheet.

  • in reply to Fabio Gou
    TI__Mastermind 47748 points

    Hi Fabio,

    Unfortunately this is port-wise meaning that individual control of p-ports via push-pull / open-drain is not possible unless the whole port is configured.

    There is a different approach around this. Please see how do conduct open-drain outputs via the output and configuration register and its implications in the FAQ here. 

    Regards,

    Tyler