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PCA9539: TCA9539-Q1 impedance is (to VCC or to GND)? when I/O pin set as output type

Vincent Chiu
Prodigy 210 points

Part Number: PCA9539

Hi TI Expert

The datasheet declare "If the I/O is configured as an output....low-impedance paths between the I/O pin and either VCC or GND.". The impedance of IO will be? Due to all I/O will be input hi-z state, we need to reserve the output pull high or low for power enable & reset pins for default values.

Regarfds,

Vincent

  • 0
    Guru 322020 points

    The output impedance can be computed with VOL / IOL or (VCC − VOH) / IOH.

  • 0
    TI__Guru* 79381 points

    Hi Vincent,

    As Clemen's pointed out, the output impedances can be estimated by using the electrical characteristics provided in the datasheet. There are also figured provided in the datasheet which provide voltage's across current loads as well. (example: ". I/O Sink Current vs Output Low Voltage for Different Temperature (TA) for VCC = 1.65 V")

    Please let us know if you have additional questions.

    -Bobby