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TS3A27518E-Q1: EN#, IN1, IN2 connected together

Matth. B.
Expert 1135 points
Part Number: TS3A27518E-Q1

Hello,

Is there any issue connecting EN#, IN1 and IN2 together. Signal will be pulled up and we ground it to enable the mux.

So the three controls pins will go low in the same time, is this configuration is allowed or do I need to put some delay between IN1, IN2 and EN#?

Thanks

Matthieu Baque

  • 0
    TI__Genius 9132 points

    Hi Matthieu,

    Using one control signal is fine if you are only going to use the highlighted mode of the device when /EN, IN1 and IN2 are all Low.

    For other device modes, you  would need to control them separately.

    Also make sure the control signal seen at the INx and /EN pins are within the range of recommended operating conditions, and the VIL and VIH(input logic low/high)pins are at the datasheet specified voltage level to control the ON/OFF signal.

    Thanks

    Saminah

  • 0 in reply to Saminah C
    Expert 1135 points

    Hello Saminah,

    Thanks for your support. Sure I want only this mode.

    I just want to be sure that there is no unknown behavior when all 3 pins (INx and /EN) are switching together like glitch and so on?

    Thanks

    Matthieu Baque

  • 0 in reply to Matth. B.
    TI__Genius 9132 points

    Hi Matthieu ,

    This device does not have fail-safe logic (Ensuring the switch stays off and the voltage on the logic pin and does not back-power Vcc  when voltage on control pin is greater than Vcc). See more details in  TI Precision Labs - Switches and muxes: What is fail-safe logic?

    if you follow the power supply recommendations to sequence VCC on first, followed by NO, NC, or COM is explained in the datasheet.

    Regards

    Saminah

  • 0 in reply to Saminah C
    Expert 1135 points

    Hi Saminah,

    My question isn't related to the VCC and power supply recommendations, I follow then. Sequence is VCC followed by NO NC and COM.

    But, I will enable the mux (disable high impedance) and switch NC to COM in the same time because signal is at pulled to VCC and tied to ground when in use. I just want to be sure that there is no drawback like NC will be connected to COM then go to high impedance then connected together.

    I guess that this use is safe but I prefer ask you in order to be sure and avoid any strange behavior in my board.

    Thanks

    Matthieu Baque

  • 0 in reply to Matth. B.
    TI__Genius 9132 points

    Hi Matthieu,

    I would take the tON and tOFF time into account as these timing characteristics determine how fast you can switch to different inputs.

    The TS3A27518E-Q1 has Break-before -make delay feature that ensures that in a multiplexer, two multiplexer paths are never electrically connected when the signal path is changed by the select input. Without break before make, you could see unwanted glitches and unexpected coupling. See more details on this spec in  Switches and muxes: What are timing characteristics?

    Hope this helps.

    Thanks

    Saminah