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TS3A24159: Normally Closed Switch During Power Loss

Part Number: TS3A24159
Other Parts Discussed in Thread: TMUX1574

Hi Team,


We are working with TS3A24159 for an upcoming application. I notice that one of the switches is normally closed when there is no signal present on the IN pins. During power loss to VCC is this switch high impedance? What is the VCC threshold that the switch turns off at? Not sure if I am missing this in the datasheet. Thank you!


Regards,


Garrret

  • Hi Garret,

    Thanks for reaching out.

    It is never recommended to leave control pins floating in an undefined state (no signal). Please make sure that there is always a signal at IN that aligns with the VIH and VIL levels of the switch.

    This switch does not have powered-off protection, meaning that the switch is not protected/high-impedance when VCC=0V or floating. Are you looking for a switch that is high-impedance when powered off? Here are some devices from the product search table of the same configuration with powered-off protection.

    The recommended operating conditions specify the minimum voltage for VCC is 1.65V.

    Best regards,
    Kate

  • Hi Kate,


    Thanks for your response. I believe I was unintentionally misleading. When I said that there was no signal present, I was referring to a low signal (<VIL) rather than floating. What is the state of the switch during power off? Does this mean that the NC to COM switch is low impedance and conducting when IN = L and VCC is lower than 1.65V?

    Regards,


    Garret

  • Hi Garret,

    Thanks for the clarification. Because TS3A24159 does not have powered-off protection, the state of the switch is not ensured to be high-impedance when the device is powered off. This means that a signal (while powered-off) at NC, NO, COM may cause back-powering of the switch or unexpected signal glitches in the signal path. If you believe that this may be a concern in your system, I recommend searching for a device with powered-off protection, such as TMUX1574, which is available in a new tiny leaded package (SOT-23-THN).

    Let me know what you think.

    Best regards,
    Kate