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TMCS1127: Request for Guidance on selecting of current sensing IC.

Mayank Mirajkar
Prodigy 80 points
Part Number: TMCS1127
Other Parts Discussed in Thread: TMCS1123,

Tool/software:

Dear Texas Instruments Support,

 

We need to select the TMCS1127B1A IC for input current sensing in a single-phase and three-phase compressor pump for our project. We would appreciate your detailed guidance on the following points:

  • Is the TMCS1127B1A compatible with measuring three-phase AC current from 0A to 20A, within the frequency range of 45Hz to 65Hz, while achieving an accuracy of 0.5%?  
  • Will the TMCS1127B1A provide the RMS value of current, or will it only provide raw data?   
  • Will the TMCS1127B1A sense the zero crossing of the AC current waveform, or will this need to be determined through logic in the code?
  • After collecting data from the TMCS1127B1A, is there a need to calibrate the current, or will it provide the final runtime actual current value?
  • Please provide any example code for the TMCS1127B1A, as well as other important data or PDFs for development.
  • Is there a GUI available for calibration?
  • After using this IC, is there a need to use a current transformer (CT), or is a CT unnecessary?

 

Thank you for your continued support.

Best regards,
Mayank Mirajkar

  • 0
    TI__Expert 7965 points

    Hello Mayank,

    Mayank Mirajkar said:
    Is the TMCS1127B1A compatible with measuring three-phase AC current from 0A to 20A, within the frequency range of 45Hz to 65Hz, while achieving an accuracy of 0.5%?

    The TMCS1127 works well for measuring current in this situation, and this is fully within the current range of the device. The maximum sensitivity error of the TMCS1127 is 1.25%, so if you wish to keep the total error of the device under 0.5% you should use a more accurate device like the TMCS1123.

    Mayank Mirajkar said:
    Will the TMCS1127B1A provide the RMS value of current, or will it only provide raw data?  

    These devices are analog devices and return an analog voltage that corresponds to the instantaneous value of the current.

    Mayank Mirajkar said:
    Will the TMCS1127B1A sense the zero crossing of the AC current waveform, or will this need to be determined through logic in the code?

    The TMCS1127B1A is a bidirectional part, with a 1.65V output corresponding to zero current on the input. So there will be no problem detecting a zero crossing on the AC current waveform.

    Mayank Mirajkar said:
    After collecting data from the TMCS1127B1A, is there a need to calibrate the current, or will it provide the final runtime actual current value?

    The TMCS1127 can be calibrated to increase the accuracy if desired.

    Mayank Mirajkar said:
    • Please provide any example code for the TMCS1127B1A, as well as other important data or PDFs for development.
    • Is there a GUI available for calibration?

    The TMCS1127B1A is not a digital part, so there is no example code or GUI associated with it.

    Mayank Mirajkar said:
    After using this IC, is there a need to use a current transformer (CT), or is a CT unnecessary?

    A CT is unnecessary using this IC as it has already converted the current input to a voltage output.

    Let me know if you have any more questions,

    Levi DV