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PCA9306: Question about the 200K pull-up resistance

Zhengquan Lu
Intellectual 1035 points
Part Number: PCA9306

Hi team,

    customer wants to use one signal to control several PCA9306 EN pin, then the 200K pull-up resistances would be in parallel. Is there any concern about this? If this is ok, how many PCA9306 devices could be controlled in this way? Thanks!

Best Regards

Zhengquan Lu

  • 0
    TI__Guru 73761 points

    Hey Zhengquan,

    My recommendation for the PCA9306 enable pin is to have the GPIO, a HI_Z input when you want it to be high (let the 200k pull up resistor to Vcc2 provide the high) and when you want to disable PCA9306, drive the enable pin low by making the GPIO an output logic low.

    Does this make sense?

    Thanks,

    -Bobby

  • 0 in reply to BOBBY
    TI__Intellectual 1035 points

    Hi Bobby,

        Thanks a lot for your help! I drew a diagram as below, could you please help to check whether my understanding is right? And when GPIO is logic low, there is still some current (3.3V/200k) on 200k resistance, right? Thanks!

    Best Regards

    Zhengquan Lu

  • 0 in reply to Zhengquan Lu
    TI__Guru 73761 points

    Hey Zhengquan,

    "could you please help to check whether my understanding is right?"

    Yes, this is exactly what I was saying. When the GPIO is in hi-Z, the PCA9306 is turned on and the reference voltage is not disturbed. When the GPIO drives low, all PCA9306 will be disabled. There will be a small amount of current from the 200k pull ups but only in the microamp range.

    Thanks,

    -Bobby