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TCA9554: the P-port voltage consideration

hui zhang
Intellectual 280 points
Part Number: TCA9554

TCA9554 datasheet shows "when an I/O in configured as an input, input voltage may be raised above VCC", what is the voltage range for the I/O when used as input?  Can I/O lower than VCC?

  • 0
    Guru 243220 points

    The recommended operating conditions show the input voltages detected as low (VIL) or high (VIH).

    If your input signals are lower than VCC, then you usually need some level shifter.

  • 0
    TI__Mastermind 49110 points

    Technically our I/O pins are 5V tolerant though if you use Vcc at for example 3.3V and pull the pin to 5V, you may see additional Icc current that is no longer in spec with the datasheet's electrical parameters.

    Using the device at a lower voltage than Vcc will result in higher shoot through currents resulting in higher supply current readings.

    If for some reason you need use your device at a different logic range than the I2C lines, you can use TCA64xx as it acts as a level translator between I2C logic and p-port logic.

    -Bobby