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ISO1212: How to interface with ADC pin of RM46L852 Microcontroller?

Saravanakumar S93
Expert 1300 points
Part Number: ISO1212
Other Parts Discussed in Thread: RM46L852, AMC1300

Hi All,

Can you please tell me, How to interface with ADC pin of RM46L852 Microcontroller with ISO1212 ?

I would like to use both, isolated digital input as well as analog current monitoring for the input pin.

Thank you.

Regards,

S.Saravanakumar

  • 0
    TI__Guru 53025 points

    Hi Saravanakumar,

    ISO1212 is a isolated digital input receiver that isolates high voltage field inputs (24V to 60V). The input to ISO1212 is a high voltage digital signal while the output is CMOS digital signal. The outputs of ISO1212 can be connected to any of the GPIOs of MCU making sure both ISO1212 and MCU are operating on the same supply voltage for logic signal compatibility.
    From the above explanation, it is clear that ISO1212 need not be interfaced to any ADC as the signal involved is digital.

    Isolated analog current monitoring can be done in many ways, I am listing below a couple of commonly used options.

    1. Using external current shunt monitor + ADC + digital isolator (ISO77xx) and connecting the isolated digital signal to MCU.
    2. Using isolated amplifier for current sensing (like AMC1300) and then interfacing it to ADC of MCU.

    Let me know if this answers your question, thank you.

    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    Expert 1300 points

    Hi,

    Since,  ISO1212 has Rshunt resistance.

    Can we able to follow the below approach?

    ISO1212=>ISO77xx => ADC.

    Regards,

    S.Saravanakumar

  • 0 in reply to Saravanakumar S93
    TI__Guru 53025 points

    Hi Saravanakumar,

    The device ISO1212 supports input voltages of upto 60V and it doesn't directly support higher voltages. The Rshunt resistor is used to divide higher input voltages such that ISO1212 can still be used with such high voltages. Please refer to the below tech note for more details on using ISO1212 for high voltages.

    The ADC needs analog input signal while ISO1212 and ISO77xx are digital devices, nether of them accept or output analog voltage. Like I mentioned earlier, if your intention is to measure current and isolate then you should follow one of the two approaches I had mentioned in my earlier post.

    Let me know if you have any other questions, thank you.

    Regards,
    Koteshwar Rao