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PCF8575 power up

Volker Meiss
Prodigy 20 points
Other Parts Discussed in Thread: PCF8575, TCA9555

Hi,
I have a question about PCF8575 after power up. According to datasheet, the device will come up with I/O logical high on outputs. Is this true?
My problem is, that I am controlling a device via the expander that maybe is not powerd up when expander comes up (another VCC group). So I maybe power the device via datalines. Only solution is that I connect the expander to the same VCC group... 

  • 0
    TI__Mastermind 30260 points

    May I suggest using the TCA9555 instead, if possible.

    The TCA9555 is a pin-2-pin equivalent device to the PCF8575, and the only difference is the removal of IOHT in the PCF8575 in favor of the integrated 100kOhm pull-up resistors.

    The TCA9555 is a newer device with an updated datasheet, and the P-ports are configured as high-Z inputs by default.