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DRV5053: Relation between hall voltage out put and current

Part Number: DRV5053
Other Parts Discussed in Thread: DRV5055, DRV425, DRV421

Hi,

I am using the DRV5053 sensor to measure the  AC current following in a current carrying conductor .I have referred to the application note for AC contactless current sensing provided by TI . It gives  information about how to sense the output of the sensor using ADC(screenshot of the reference manual is attached ) which is a voltage output but it doesn't mention how to find the current from that voltage output.It will be really great if somebody can help me with the relation between the voltage output and current flowing.

Thanks 

  • Hello Stuti,

    Thanks for your interest in TI designs. The output voltage of the DRV5053 or DRV5055 is linearly related to the magnetic field. You can calculate the magnetic field based off of the specified sensitivity(mV/mT) in the datasheet. Once you have mT, then you can calculate the current using Ampere's Law as seen in the same document.

    Sincerely,

    Peter Iliya

    Current Sensing Applications

  • Hi Peter,

                  Thanks for the quick response.

    I have another doubt related to the use of this formula since I will be using a flux concentrator for concentrating the flux generated by the current carrying conductor ,I should consider the relative permeability of the material and the air gap right?

    Secondly I have observed that the value of the hall sensor at 0 current condition is not exactly 1V for all the sensor it varies slightly from .94V to 1V  .So the measurement is different for different sensor how should this be handled in general?

    Thanks

    Regards

    Stuti

  • Hello Stuti,

    This is correct. You will need to account for permeability of the flux concentrator. You might want to look into using the DRV425, which would be more accurate than DRV5053. You can learn about operational theory and use our calculators at the product page here:
    www.ti.com/.../toolssoftware

    The zero-current (zero magnetic field) output voltage of the DRV5053 can vary 0.9 to 1.15V over -40C to +125C temperature. The only way to handle this is to design around this. The DRV5055 will have better performance and so if this is a problem I would move to DRV5055.

    If you have any more questions, please post what current levels you are working and any other schematic information so we can assist you better the next time you post to the forum. Thanks for choosing TI.

    Sincerely,
    Peter Iliya
    Current Sensing Applications
  • Hello Stuti,

    Thanks again for using the forum to help resolve your questions.  You may also want to consider the DRV421.  This has a few more limitations on the core and air gap.  There is plenty on information on our DRV421 product page if this is an interest to you. 

    As for the flux seen through the concentrator you are correct in that you will see different results depending on the permeability and air gap size.  The biggest factor will be the air gap.  You can use a tool like FEMM that is free to experiment with this.

    As Peter mentioned what current level are you trying to measure.  This will help in helping select.  Also what accuracy are you looking into.  The DRV421 is most likely the most accurate but cost and the range of the current may not be what you are looking for.