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ISOW7841: Driving ADS131M06 with ISOW7841 + ISOW7842/ISO7842

Aswin Venu
Prodigy 40 points
Part Number: ISOW7841
Other Parts Discussed in Thread: ISO7842, ADS131M06, ISOW7842

Hi,

 I am making an industrial data acquisition module using ADS131M06. I wanted to isolate the ADC supply from the main supply along with the communication lines to the microcontroller. I saw the reference design of achieving the same with ISOW7841. But in my case I wanted two additional lines also to be isolated which are DRDY and RESET.  Here I have two options one is adding another ISOW7842 and cascading the isolated power supply together or use ISO7842 and drive the isolated channel powersupply using ISOW7841. In the second case I dont know that the ISOW7841 has enough power to run the second ISO7842. Attaching the schematics of both proposed solutions. Please let me know is it feasible?

Regards,.

Aswin

  • 0
    TI__Mastermind 49495 points

    Hi Aswin,

    Please see below my comments regarding the two options you have listed out.

    1. Please note that the VISO outputs of ISOW devices cannot be tied together directly. This is true for any DC power supply output, they can't be connected together as one supply will short the other.
    2. This option should work fine. ISOW supports upto 130mA of output current and I assume ADS131M06 doesn't much of current. ISO7842 should also not require much of the current and hence I do not see any issue here.

    I am not sure on how clean the ADS131M06 supply input needs to be, based on that you may need to use a LC/π-filter or an LDO at the output of VISO. Thanks..

    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    Prodigy 40 points

    Hi Koteshwar,

    Thank you for such a fast reply. The schematics wasn't a complete one. ADS131M06 requires  clean analog power source to operate (Its a 24bit precision ADC).

    Is there any chance I can get some samples of ISOW7841, ISO7842?

    Thanks and Regards,

    Aswin

  • 0 in reply to Aswin Venu
    TI__Mastermind 49495 points

    hi Aswin,

    Samples can be requested from the TI website. If possible, please do use your work or university email ID which will enable you to order free samples. Thanks.

    Regards,
    Koteshwar Rao