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TCA6418E: State of GPIO pins before and at power-on

Part Number: TCA6418E

Hello Sir or Madam.

I'm using the TCA641E as an I2C slave in one of my designs. 

There are 2 things I need to know about the GPIO pins for the TCA641E:

  1. Before power is applied to the GPIO chip, what is the state of the GPIO pins?
  2. After power is applied, but before any programming or communication has happened, what is the state of the GPIO pins?

According to the datasheet (page 7), the answer to #2 is "At power on, the GPIOs are configured as inputs with internal 50-kΩ pulldown resistors enabled; however, the system master can enable the GPIOs to function as inputs or outputs."

I could not find an answer to #1 on the datasheet, and technical support over the phone did not have an answer to #1.

I need a confirmation to both questions please, as it determines how I setup my schematic (include pullups, pulldowns, nothing at all, etc).

Thank you for your time.

Best Regards,

Jake Sheroff

  • Hello Jake,

    1)  The GPIOs before power (VCC=0V) is applied is high-z.

    2)  The GPIOs are by default pull down to ground by  55k Ohms until programmed. This is assuming Vcc is ON and within the operating range of the device.

    Francis Houde

  • In reply to fhoude:

    Hello Francis.

    Excellent, this is exactly what I needed to know.

    Thank you and have a great day.


    Best Regards,

    Jake Sheroff

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