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a 256-channel analog multiplexer

Noushin Ghaderi
Prodigy 50 points
Other Parts Discussed in Thread: TMUX1104, TMUX1108, TMUX1109

Hi, 

I need a 256-channel analog multiplexer. Would you please introduce me a chip in this regard?

Really appreciate it.

Best

  • 0
    TI__Prodigy 547 points

    Hi Noushin,

    We have a variety of multiplexers of all differing in sizes, performance and # channels (MAX: 32 ch). For us to provide the most appropriate multiplexer, we will need more information. What are the requirements for bandwidth, voltage, # of channels, leakage, and any other application-related specifications? If possible, please provide a block diagram or a description of the MUX application.

    Thanks,
    Jon

  • 0 in reply to Jon Alejandro
    Prodigy 50 points

    Hi, 

    thank you for answering. 

    I need the 256- channel multiplexer, to select one of the 256 sensor board channels. the block diagram of a 3*3 sensor array is shown bellow.

    A current in the range of nA should be selected and passed by the multiplexer switches. The voltage can be limited to 5 volt. The speed is not so critical. A clock in the range of KHz is good enough. but the leakage current must be bellow pA. 

    Thank you again.

    Best,

  • 0 in reply to Noushin Ghaderi
    TI__Prodigy 547 points

    Hi Noushin,

    How many ADCs/MPs are you planning on using for the 256 sensor board channels? We don't have a 256:1 MUX, at 5V, with below pico-amps of leakage. We don’t have any Muxes that fit that as a single package. The best resolution I see to that is using smaller MUXes as building blocks. With our parts it seems that we could use 64 4:1 Muxes, followed by group of 8 8:1 Muxes, finally one 8:1 Mux. This requires 73. 

    Thanks,
    Jon

  • 0 in reply to Jon Alejandro
    Prodigy 50 points

    Hi Jon,

    Thank you for your guidance. Then with the mentioned arrangement, can you introduce me for the lowest possible leakage current chips? I mean the leakage current when the switches are on. I need the accumulated leakage current in the 3 stages of MUXs to be in the range of pA.

    Thank you again.

    Best,

  • 0 in reply to Noushin Ghaderi
    TI__Prodigy 547 points

    Hi Noushin,

    Based on a 5V supply, the lowest leakage products in our portfolio are the TMUX1108 (8:1 MUX) and the TMUX1104 or TMUX1109 (4:1 MUX). I would recommend different variations of these depending on your layout or requirements. I would be wary that adding all these Muxes together could cause the total leakage to creep up to nA. Our TMUX11XX family is our lowest leakage family in low-voltage. 

    Thanks,

    Jon

  • 0 in reply to Jon Alejandro
    Prodigy 50 points

    Thank you so much Jon.