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TCA4307: Powered-off high-impedance I2C pins

Charles SALMON
Prodigy 60 points
Part Number: TCA4307

Hello,

I am designing a host with an I2C master that is connected to a I2C slave device.

Most of the time, the host is deep sleeping, and I want to make sure the system consumes very low power when deepsleeping.

In deepsleep, the I2C bus SDA/SCL are HiZ.

1) Is it sufficient to put the TCA4307 into  shutdown mode ? Or do I need to put the ENABLE pin to Low ?

2) Unfortunately I can not control the enable pin, so I need to connect it to Vcc ?

I can however control the Vcc of the TCA4307 (and I2C device attached to it).

What if I switch-off the slave power when in deep sleep mode ?

Thanks,

Charles

  • 0
    Guru 243220 points

    1. The shutdown mode is entered by pulling EN low.

    2. If you cannot control EN, then you have to force VCC to 0 V; this will also disable the device and make the I/Os Hi-Z.

    The TCA itself does not care what you do with the slave power. But the slaves might not be happy if the pull-up resistors are active while their own power is off.