• State Resolved
  • Locked Locked
  • Replies 7 replies
  • Subscribers 35 subscribers
  • Views 635 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Multiple channel inductive sensing

Panson Poon
Intellectual 420 points
Other Parts Discussed in Thread: TS5A3359

Hi,

Is it possible to use one LDC1000 plus analog multiplier (or something similar) to sense multiple coils similar to traditional multiple-channel ADC?

Cheers,

Suk Tan

  • 0
    TI__Genius 9300 points

    It is.

    The trade-off is the reduced conversion speed: It will take several oscillations to get the LC tank going, so the 1st (and possibly 2nd) sample is incorrect.

    Also, mux will add extra capacitance - it should be taken into account, if LC cap is small.

  • 0 in reply to Evgeny Fomin
    Intellectual 775 points

    Does TI plan to release a similar product with more than one input?

  • 0 in reply to Etienne Alepins
    TI__Genius 9300 points

    Yes, we will have multi-channel devices in the future.

  • 0 in reply to Evgeny Fomin
    Prodigy 80 points

    Any idea what the projected timeline for these multi-channel devices would be?

    I'm presently experimenting with my LDC1000 and an array of TS5A3359 analog switches to multiplex an array of 12 coils (pushed it up to 5khz scan rate -> 416Hz for the whole array) and it seems to be working pretty well so far, but having multi-channel capability integrated into the LDC would be much, much nicer.

  • 0 in reply to Bruce Hansen
    TI__Prodigy 160 points

    Hi Bruce,

    The LDC1000 is the first device in our new LDC family. While we can’t publicly disclose roadmap information, we can tell you that our design team is hard at work. Please stay tuned!

    Thanks!

  • 0 in reply to Bruce Hansen
    Prodigy 10 points

    Hi Bruce (or others?)

    I'm interested in your multi-channel application. Would you care to share more?

    For example, details of your circuit, where you have placed the switches (in INA or INB or both?)

    If you use multiple coils they must be physically separte from each other. Have you found any issues about the length of signal path to distant coils?

    What about distance between each coil?

    Any idea on a practical upper limit for the number of coils?

    Thanks

    Regards - Charles

  • 0 in reply to Charles Palmer
    Prodigy 80 points

    Hi Charles,

    I'm switching both INA and INB to my array of coils and they are spaced at intervals of 1 to 2 inches (center to center, not gap between).
    My LDC1000 circuit is positioned off to the side with 8 to 12 inches of wire to each coil (some thin twisted pair stuff I had in the junk box)

    I would guess that the upper limit on the number of coils would probably largely be determined by the switches used to select each coil.
    The TS5A3359's I'm using do definitely contribute a noticeable amount of capacitance to the parallel LC tank circuit, but I suppose the impact of this would depend on what resonant frequency you're aiming for and whether the switch capacitance is significant compared to your tank capacitance (in my case it is).

     - Bruce