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AMC1311: Sch for AMC1311

Tarun Kumar2
Prodigy 210 points
Part Number: AMC1311
Other Parts Discussed in Thread: , AMC3330

Hi All,

           We wants to implement AMC1311 with Our microcontroller ADC pin(12bit ADC, VIN ADC- 1.4V) to measure the 230VAC, 50Hz. For this integration we are  requiring the reference schematic,
           please share the schematic for the reference.

           Looking for the favorable response.

           Thanks In Advance.

Best Regards

Tarun Kumar

  • 0
    TI__Guru 50301 points

    Hi Tarun,

    The AMC1311 has a 0-2V input ideal for DC voltage sensing. Since you are interested in measuring an AC signal, additional front end circuitry would be necessary such that the measurement can swing +/-1V within the 0-2V input range. Other customers have implemented this as shown in the thread below. 

    https://e2e.ti.com/support/amplifiers/f/amplifiers-forum/876890/amc1311-3phase-3wire-voltage-measurement 

    As for interfacing with your MCU, I assume that the ADC input is single-ended? 

    Please see Figure 22. Output Voltage vs Input Voltage in the datasheet. 

    Directly connecting the differential signal from the isolated amplifier to a differential ADC is the preferred way to interface as it allows for the most common-mode rejection, leading to the highest SNR measurement possible.

    Many MCU’s do not have differential inputs, only single ended. This is why a differential to single-ended conversion is necessary. There is an added benefit here of being able to gain or attenuate the signal such that it matches the maximum input range of the MCU, and filtering can be implemented. As shown in this document: https://www.ti.com/lit/an/sbaa229/sbaa229.pdf

    The last way would be to connect the negative output from the AMC1311 directly to the ADC with the positive output tied to GND through a weak resistor. This allows for direct connection to a single-ended MCU, but there is no filtering or matching of the full-scale range.  The positive input should not be tied directly to GND as it is a driven output. Connect the positive output to GND through a 10k resistor to limit the current and protect the device.

    Please see the AMC1311EVM user's guide for an example implementation: https://www.ti.com/tool/AMC1311EVM

    Another option would be to use the AMC3330. This device has a +/-1V input range and is ideal for AC voltage sensing. The additional front end circuitry that the AMC1311 requires would not be necessary. The back end requirement would be the same however. The AMC3330 also has an integrated DC/DC converter which will save board space and reduce the complexity of the design, removing the need for a high side power supply. 

    Please see this blog for additional details: https://e2e.ti.com/blogs_/b/analogwire/posts/simplify-your-isolated-current-and-voltage-sensing-designs-with-single-supply-isolated-amplifiers-and-adcs