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DDC118: DDC118

Doug Real
Prodigy 10 points
Part Number: DDC118
Other Parts Discussed in Thread: TMUX6136

We are considering the TMUX6136 in front of the DDC118 and willing to accept some degraded specs. The system is almost a DC response system so no high frequencies. We've looked at reed relays with slightly better performance but would like to stay all solid state. Is there a better solution for muxing very low current signals before the DDC118? (0-5V only and down to 10E-10 ohms preferable)

  • 0
    TI__Expert 4590 points

    Hi Doug,

    That is an interesting question. I have never muxed signals into one DDC channel but I don't see any major issues. I think the Ron will not make any difference nor the parasitic capacitance. My concern would be with current leakages and I assume that you have a mechanism to remove charge injection from the mux switching from one channel to another (which I got no idea what that would be). This could be simple, like throwing away the first sample after the switch, or calibrating for it...

    I'll click the answer as resolved, but feel free to bring any further concerns, if any. Also will call the attention from some folks at the MUX side to see if they have some other ideas beyond your suggestion.

    Regards,
    Edu

  • 0 in reply to Eduardo Bartolome
    TI__Genius 9132 points

    Hi Doug,

    We do have Precision Multiplexers in our Switches and Multiplexers portfolio that are used in high accuracy measurement systems requiring very small leakage current to minimize offset error and signal distortion

    In 2:1, 2 channel configuration, the TMUX1136 has wide supply range (1.08 V to 5.5 V) and very low leakage current of 3 pA

    If you are looking for a different configuration, the TMUX11xx devices have very low on and off leakage currents and low charge injection, allowing them to be used in high precision measurement applications.

    Regards

    Saminah