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DAC8742H: Mux and demux of HART signal using DAC8742H

Abishek V
Prodigy 165 points
Part Number: DAC8742H

Hi 

We are using DAC8742H HART modem to transmit and receive HART signal. We need to implement HART interface for 16 channels. So we are using CD74HC4067M96 as 16:1 Mux and Demux to transmit and receive HART signals using a single DAC8742H IC. Please clarify whether DAC8742H is capable of this kind of Mux and demux of HART signal

Regards,

Abishek V

  • 0
    TI__Guru* 93975 points

    Abishek,

    Offhand, I don't see any issues with using the multiplexer to look at multiple channels of HART signals. I think that the series resistance and the capacitance on the input and output of the multiplexer should be low enough to not interfere with the HART signal.

    One thing I would recommend would be to get a DAC8742HEVM to test this configuration. You would use the single DAC and connect the multiplexer to test the connections between the device and multiple HART signals.

    Do you have a block diagram of what you would put together?

    Joseph WU

  • 0 in reply to Joseph Wu
    Prodigy 165 points
    Hi thanks for your response. Please find the block diagram for your reference. We need SIL certification for the implementation. so Hope there will be no issue while using like this way.
    Also please suggest a suitable 16:1 MUX and 1:16 Demux IC for the above implementaion.
    Regrads,
    Abishek V
  • 0 in reply to Abishek V
    TI__Guru* 93975 points

    Abishek,

    Thanks for the block diagram, I just wanted to make sure that I understood how you were putting it together.

    I'm not sure I can give a mux/de-mux recommendation to you. I've never put this application together, and I'm not very familiar the multiplexer product line. Because this is inserted into the HART signal chain, I think that low series resistance and capacitance is important to the application. Again, I would recommend getting the DAC8742HEVM and a board for the CD74HC4067M96 just to test the application. I think this would be a good test for your planned system.

    Joseph Wu

  • 0 in reply to Joseph Wu
    Prodigy 165 points

    Hi

    Thanks for your response. Is there any chance for me to get the board as sample for testing purpose?
    And to use mux in between DAC8742H what are the parameters we need to consider?
    Please clarify these two questions.
    Regards,
    Abishek V
  • 0 in reply to Abishek V
    TI__Guru* 93975 points

    Abishek,

    Do you know your TI representative for your company? If you work with them, you may be able to get an EVM board. I think they'll want to know what project or application you're working on. If that doesn't work, can I contact you through your email from the E2E?

    As for the mux, I think the series resistance and the input/output capacitance are the biggest factors that I would consider. If either are large enough, them may disrupt the AC coupling or cause HART signal to be filtered.

    Joseph Wu