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Original question:

ADS131M04: Help with sample code

ADS131M04: BW and current inverter use case

RJ
Intellectual 2550 points
Part Number: ADS131M04
Other Parts Discussed in Thread: TIDA-010037,

Hi Team,

A few question - looking at a split phase meter design with ANSI C12, 0.2 accuracy. Found the TIDA-010037 and the ADS131M04.

  • would you recommend this device for the application?
  • would this be capable of current control for the inverter with control BW of 4-10kHz?
  • one of the issues with following the ref design is their DSP is in a different board so the SPI connects between boards with flat cables, but in this design it also takes the clock from the micro that is 8MHz, that will not work with flat cable. Would we be able to just replace it with a 8MHz oscillator, should that be ok? Will it cause any sync issue?
  • can the ADS131M04 be used for general current sense as well for the inverter? It will be good if we can use the same current sensor for energy measurement and inverter current control.
  • We are trying to figure out the BW of this ADC and BW after the SINC filter as the filter itself has a settling time of 1112clk for 2560SR
  • can this IC be used without the filters as well?

I appreciate all the help you can provide!

Regards,

Ramon

  • 0
    TI__Guru* 92715 points

    Ramon,


    Here are answers to your questions:

    I would recommend this device for energy metering. This device is targeted for those type of applications. However, with the current control for the inverter, I'm not sure if it's quite fast enough.

    The maximum data rate for this device is 32kSPS. However the accumulation of data uses a sinc3 digital filter. This means that the output data is basically a moving average of the last three data periods. This means that the device will have some amount of latency, and a frequency response. The frequency is shown here:

    The fMOD/OSR is the equivalent of the data rate. At 32kSPS, the 1 represents 32kHz. The -3db point is about 8.3kHz.

    The CLKIN signal can come from an external oscillator, and doesn't need to be completely synchronous with the master. The master device can just collect data when the device indicates a conversion has completed.

    This device can be used for current measurements as well. If you look at the application section in the datasheet, an energy meter application is shown with voltage and current measurements.

    The digital filter and its frequency response is integrated into the measurement. It cannot be turned off and separated from the ADC data.


    Joseph Wu