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Original question:

ADS1018: Suitable ADC required to monitor 3-phase AC Load Using Current Transformer

ISO7741: Can we use Isolators in between Sensors and ADC

Naveen K1
Intellectual 870 points
Part Number: ISO7741
Other Parts Discussed in Thread: ISOM8110, ISO6721

Hi,

We are developing a Energy Monitoring device. Energy Monitoring IC communication pins are directly connected to CC3220MODSF12MOBR (MCU). Neutral will be connected to MCU GND and common VDD used for MCU and Energy Meter IC.

4 to 20mA output and 0-10VDC Output Sensors will be connected to MCU. We are having Following Query;

1. Neutral will not be affect the performance, Working of the MCU in the RF,EMI prospective for the Wi-Fi communication, right?

2. We need to provide the Isolation between Sensors and AC signal (Neutral) for safety prospective. So we are thinking to Provide the Isolation between the Sensor Port and MCU. We aware we can use Isolators in Digital signal like SPI,I2C,etc, but we are not sure we can use Isolators in Analog signals. So kindly advice, Can we use the Isolators between Sensor output and ADC pin of the MCU? Any degradation of Analog signal? If we can use the Isolators, kindly suggest the Isolator IC.

Thanks and regards,

Naveen K

  • 0
    TI__Genius 17825 points

    Hello,

    Thank you for your question.

    Naveen K1 said:
    Neutral will not be affect the performance, Working of the MCU in the RF,EMI prospective for the Wi-Fi communication, right?

    I am not fully sure on what you mean by this. A block diagram or schematic will help us understand more clearly.

    Naveen K1 said:
    2. We need to provide the Isolation between Sensors and AC signal (Neutral) for safety prospective. So we are thinking to Provide the Isolation between the Sensor Port and MCU. We aware we can use Isolators in Digital signal like SPI,I2C,etc, but we are not sure we can use Isolators in Analog signals. So kindly advice, Can we use the Isolators between Sensor output and ADC pin of the MCU? Any degradation of Analog signal? If we can use the Isolators, kindly suggest the Isolator IC.

    I understand that you require isolation between the sensor and the MCU. Since the signals are analog, the ISOM8110 Opto-Emulator device might be an option but there I am not able to tell as I would have to see a schematic or diagram to confirm what you mean. Since you are worried about signal degradation of the analog signal, the Isolated Amplifiers product like might be able to help you more. Please post your question to this forum as they may be able to help answer your questions: Amplifiers forum - Amplifiers - TI E2E support forums

    Regards,
    Aaditya Vittal

  • 0 in reply to Aaditya V.
    Intellectual 870 points

    Hi Aaditya,

    Thank you for the information.

    In the Below Block diagram, you can see Neutral will be connected to MCU GND and Energy Meter IC (ADS131M03I) GND. Common VDD used for MCU and Energy Meter IC.

    1. Neutral is a AC right, which is connected to Energy Meter IC and MCU GND. So this connected Neutral will affect the MCU performance? It will not impact on MCU Wi-Fi RF performance or EMI issue?

    2. In the Block diagram, between OPAMP and MCU, there will be an Isolator IC for safety prospective. because connected Analog sensors(Ex: Temperature/Vibration/other) will be installed in the user active area. My Question is, Can we use Isolators in between OPAMP and MCU ADC pin? If we use Isolator any major issues on the Accuracy prospective?

    Thanks and regards,

    Naveen K

  • 0 in reply to Naveen K1
    TI__Genius 17825 points

    Hi Naveen, 

    Please give me an additional day to review this information. 

    Regards,
    Aaditya Vittal

  • +1 in reply to Aaditya V.
    TI__Genius 17825 points

    Hello,

    Thank you for your patience. 

    Looking at the block diagram you have provided, it looks like you would like to have isolation for the UART signals along with analog signals from the OPAMP. Considering this, there are a few points I would like to make:

    For digital signals such as UART signals, we recommend using our digital isolators, such as the ISO6721 device (Isolating UART Signals)

    Naveen K1 said:
    Can we use Isolators in between OPAMP and MCU ADC pin?

    Isolation options for analog signals depends on the level of signal accuracy that you require. If signalaccuracy is not as important, we recommend using the ISOM8110 device. If signal accuracy is important, we would recommend an isolated amplifier (Amplifiers forum - TI E2E support forums)

    Naveen K1 said:

    Neutral is a AC right, which is connected to Energy Meter IC and MCU GND. So this connected Neutral will affect the MCU performance? It will not impact on MCU Wi-Fi RF performance or EMI issue?

    Your question regarding the neutral being connected with MCU ground is best asked to the experts on the MCU device. Please post your question regarding the WIFI E2E forum: Wi-Fi forum - Wi-Fi - TI E2E support forums

    Regards,
    Aaditya Vittal