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Is there any multiplexer that keep maintaining the control input decision after the input is off?

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Replies: 2

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Dear experts,

Our application requires some tricky multiplexer that maintains the previous decision of control input after the input is off.

Since we have seen and used various multiplexers and switches from Texas Instruments,

we would kindly ask the experts if there is a suitable option for our requirements.

Thank you in advance for your sincere advice.

Best regards,

  • Hi Hyun,

    We don't currently have any devices that will retain a logic signal passed to the device after the signal source shuts off.

    However, with the addition of a gated D - Latch, shown below, or something similar can help meet the goals of the application. 

    The Truth Table is as follows:

    D E Q /Q
    x 0 Previous Q Previous /Q
    0 1 0 1
    1 1 1 0

    In this example you would need 2 control signals to perform this task. To make sure that the device works as expected with control signals that will not always be present a stronger pull-down would be recommended on E so that E will go to zero quicker than D would so that the logic state would be retained when the control signal turns off. The D pin should also be asserted before the E pin to ensure when the E pin goes high the latch will produce the correct logic level on the control pin. 

    If you could also give me a bit more detail into the application such as multiplexer configuration needed, channels required, signals voltage levels, Analog or Digital signal, signal bandwidth, and the load impedance so I can look a little deeper into this application and work to find an acceptable solution.

    Best,

    Parker Dodson

  • In reply to Parker Dodson:

    Dear Parker,

    A series of latches would be a really nice solution. It seems easy to implement with any types of multiplexers.

    Thank you so much for your considerations.