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ADS1298R input signal switch choice

Martin Daricek
Prodigy 70 points
Other Parts Discussed in Thread: TS5A23157, ADS1298R, TS3A24157, TS3A24159

Hello,
I would like to switch/mux ADS1298R input channels to different signal sources, e.g. to switch between V6 electrode and respiration circuitry to channel 1. Switch should be dual SPDT digitally controlled IC, with similar (or better :) specification like mux inside the ADS1298R. I viewed at several IC, like TS3A24159, TS3A24157 or TS5A23157. Are these circuits suitable for this purpose? Which is the best one? Isn't s better choice to use two separated SPDT IC`s (due to crosstalk)?

 Thank you for answer, Martin

  • 0
    TI__Guru 62326 points

    Hi Martin, 

    I took a glance at the TS3Axxxxx switches and they seem to be ok for this application (they specifically mention "low-voltage DAQ" - ECG and Respiration certainly fit that description).

    It looks like there is a NC and NO input on one side of the device, and a COM output on the other side, in most pinouts. The COM pin would go to Channel 1. Is this what you are looking to implement?

    I do not know the switches portfolio very well, but you may have to take other characteristics into consideration, such as how fast you can switch between inputs and what frequencies they can handle without distortion (remember your RESP_MOD signal is 32kHz/64kHz).

    For more specific questions, I would suggest consulting the TI - Interface group:

    https://e2e.ti.com/support/interface/etc_interface/default.aspx.

    Best Regards,

  • 0 in reply to Ryan Andrews
    Prodigy 70 points

    Hi Ryan,

    thank for answer. Connection topology is known and bandwidth is much better than needed. Question is about parameters of switch, like offset, noise, signal distortion, charge injection, etc. I don't know which parameters of the switch meet the specification of the mux, which is inside, because there isn't mux spec in ADS1298R datasheet. That's the reason, why I posted this topic here. I'm sure that TI manufactures mux from ADS1298R (or similar) as stand alone chip.

    Thanks for advice, I will post this topic also in the signal switches forum.

    Martin

  • 0 in reply to Martin Daricek
    TI__Guru 62326 points

    Martin - 

    Thanks for clarifying the parameters you are interested in. If I can find this information for the ADS1298R mux, I will let you know on this thread. :)

    Regards,

  • 0 in reply to Ryan Andrews
    Prodigy 70 points

    hi Ryan, I will look forward to it. I'm sure this information will be useful for everyone and will make ADS129X family IC's even more popular.

    martin