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ADS7042: 4-20mA receiver reference design against CN0336

Shinichi Inoue
Guru 21841 points
Part Number: ADS7042
Other Parts Discussed in Thread: REF3325, , ISO7741, OPA2320

Dear Specialists,

My customer is considering 4-20mA analog design.

He is interested in CN0336 reference design of ADI.

CN0336 is designed for simple 4-20mA receiver, it consist of opamp, SAR ADC and Isolator.

I'd like to promote similar design, but I cannot find suitable one from reference design.

Could you please provide the same concept design.

I appreciate your great help in advance.

Best regards,

Shinichi

  • 0
    TI__Guru* 98275 points
    Shinichi-san,


    I think it would take some time to build up a design, but I don't think this design topology is unique and it could certainly be done with TI components.

    First, The ADS7042 would be a good small device to use, but it does not have an internal reference, and uses the supply as the reference. I would use the REF3325 device as the supply and reference. The REF3325 would run off of a 3.3V supply.

    Isolation could be done with the ISO7741, and this device has been paired with some SAR ADCs in the past. The Viso supply would come from the 2.5V from the REF3325.

    The op-amp would also run from the 3.3V supply, I think you could use the OPA2320 and have that as the gain/level shift from the resistor measurement and the reference buffer.

    Again, I would need to construct this circuit to test it, but it is worth simulating to check the ranges and settling of the SAR input driver.


    Joseph Wu
  • 0 in reply to Joseph Wu
    Guru 21841 points
    Hi Jeseph,

    Thank you for your reply.

    I understand there isn't reference design now and you'll make it.

    At this time I'll promote ADS7042, REF3325, ISO7741 and OPA2320.

    Could you please inform if you can create a reference design.

    I appreciate your great help.

    Best regards,
    Shinichi
  • 0 in reply to Shinichi Inoue
    TI__Guru* 98275 points

    Shinichi-san,

    I think it is very likely that we will work on a design similar to this. Note that it does take a significant amount of time to get this type of collateral together. I will contact you when we are able to get a design.


    Joseph Wu