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Product selection

Liu Yang
Genius 10265 points

Hi team,

I am measuring a welding-current with a Hall effect sensor (LF310S).
The output of the sensor is 0-0.25A. My measuring equipment needs an analog input signal of 0-1V.
I do have a 0.1Ohm and/or 1Ohm shunt resistor to get a dropoff-voltage of 0.025V (0.1Ohm shunt) or 0.25V (1Ohm shunt).
This voltage dropoff I need to amplify to a range of 0-1V. The frequency of the measured signal is 80kHz.

Do you think a current sense amplifier is the right choice here? Because I couldn't find one that fits my purpose.
Helping me with the selection would be very kind.

Beat Regards,
Tom Liu

  • 0
    TI__Mastermind 27715 points

    Hi Tom,

    What's the common-mode voltage of the Hall sensor output? If it is high (>12V or so), then a current sense amplifier is needed, if it is not, then a normal op amp should work fine.

    The required gain is either 4x (0.25V to 1V) or 40x (0.025V to 1V). Current sense amplifiers tend to have higher gain, so you could use the 0.1Ohm shunt and pick something like the INA180A2 (G=50) or INA199x2 (G=50).

    Best regards,

    Ian Williams
    Applications Manager
    Current Sensing

  • 0 in reply to Ian Williams
    TI__Genius 10265 points

    Hi Ian,

    I tried to identify the common mode voltage of my sensor (LEM LF310-S with a power supply of +-15V DC, datasheet attached) but couldn't manage to do so.

    Datenblatt_LF_310-S.pdf


    Beat Regards,
    Tom Liu

  • 0 in reply to Liu Yang
    Guru 140200 points

    Hi Liu,

    this sensor does not produce a common mode voltage. So, as already mentioned by Ian, a simple OPAmp should do. According to the datasheet of LF310-S choose an appropriate RM.

    Kai