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TCA9555 - Pull-up/pull-down resistors required for I2C address pins A0-A2?

Jonathan Bender
Expert 7895 points
Other Parts Discussed in Thread: TCA9555

Hello,

On the pin descriptions for TCA9555 (page 3), it states A0-A2 should be connected directly to VCC or GND:

The test conditions for the input current parameter (page 14) seems to support this:


However, Figure 15 (page 22) shows a 10 kohm pull-up to VCC for A2, while A1 and A0 are tied directly to ground:

Is a resistor between A0-A2 and VCC required? If not, does including it provide any additional benefit, or potentially introduce any issues?

Thanks,

Jonathan

  • 0
    TI__Genius 16510 points
    Jonathan,

    There is no hard requirement that the address pins need a pullup resistor.

    You can connect the address pins directly to VCCI or to GND. However, many customers like to use a series resistor to power rail because in the event of some internal damage (ESD event perhaps that caused an internal short to ground for example), the series resistor would limit the maximum current that could flow. Series resistors are used more as precautionary measurements, and are not requirements.

    There are no issues presented with the use of one (or without), it comes down to customers. Many customers do like to use them as an extra safe step.
  • 0 in reply to Jonathan Valdez
    TI__Expert 7895 points
    Thanks Jonathan, makes sense and seems like cheap insurance to me.

    I appreciate the quick reply and detailed explanation.

    Jonathan