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TMUX1108: Connection of the GPIO to the MCU

Jonathan Navor
Expert 7805 points
Part Number: TMUX1108

Hi Team,

Good day! I am posting this in behalf of the customer. Kindly check as per shown below. 

I would like to ask whether the multiplexer TMUX1108 can be directly connected to the GPIO of the MCU. I want to use a multiplexer to connect the sensor. The sensor transmits a 10M square wave signal (analog signal).

The voltage of my single-chip microcomputer is 3.3V. I see that the reference voltage of the TMUX1108 data sheet is 1.08V to 5.5V, but the current is only uA.

In this case, please confirm if TMUX1108 be directly connected to the GPIO of the single-chip microcomputer and share us the technical reference for it. 

Thank you in advance. 

Best regards,

Jonathan

  • 0
    Guru 243180 points

    The control inputs (VSEL and VEN) are plain CMOS inputs and can be connected directly to the GPIOs. The allowed high voltage is specified as VIH; the 3.3 V output will work with that.

  • 0
    Prodigy 10 points

    Thank you for your reply. I would like to know whether a current-limiting resistor should be added between the power supply pin of the MCU and the power supply pin of TMUX1108, or the impedance of the switch under normal operation (3.3v).

  • 0 in reply to haibo yu
    Guru 243180 points

    Power supplies should have as low an impedance as possible. You can use the same supply for the microcontroller and the switch.

    At 3.3 V, the analog switches have a typical impedance of 4 Ω.

  • 0
    TI__Mastermind 23373 points

    Hey Jonathan,

    You can directly connect these. However, I'm not sure if you're understanding the current spec correctly. The source or drain continuous current (the current actually going through the analog switch signal path) have the ab max rated to +-30mA. The only uA currents i'm seeing are the current leakage and the supply current. This is relating to the power consumption of the device, rather than the maximum input allowed. 

    To touch on haibo's question as well, the impedance on the power supply line should be low, as clemens mentioned. Ideally, as the layout guidelines in section 11 of the datasheet show, the only thing on the power supply lines are the decoupling caps (0.1uF) to GND.

    Thanks,
    Rami