TCA9543A: TCA9543A SCH review

The VCC of the mux should be the lowest I²C or control signal voltage, i.e., 1.8 V.

The mux passes through low-level I²C signals (near 0 V), and opens the switch for high-level signals (near its own VCC or higher) so that the output voltage is determined by the respective pull-up resistor. But with a 3.3 V supply, at 1.8 V signal is passed through and will be too low for 3.3 V devices.

Also, the high level of the control inputs must be near or abovec VCC.

Hi Clemens

Thanks for your help

BRs

Brian

That image shows a transmission gate. But the TCA9543A uses a single N-channel MOSFET with the gate connected to VCC. The Vpass characteristics are the gate-to-source voltage characteristics of this MOSFET. (Opening the switch for voltages near or above VCC is required to allow voltage translation.)