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INA146: Single Supply OpAmp for AC measurement

Jan Bock
Intellectual 2830 points
Part Number: INA146

Hi Team, 

my customer looks for an OpAmp to realize single supply AC voltage measurement. 

Currently he uses INA146 with dual supply. These are the requirements:

  • 12 V Rail supply voltage
  • input voltage +-5V @ 50kHz max
  • output range max +0-10V

Can you please provide a recommendation for an OpAmp and the circuit. I have already sent these documents to the customer: 

Thanks 

Jan

  • 0
    TI__Guru 59961 points

    Hi Jan,

    Currently he uses INA146 with dual supply. These are the requirements:

    • 12 V Rail supply voltage
    • input voltage +-5V @ 50kHz max
    • output range max +0-10V

    Based on the requirement above, I do not believe that INA146 will work correctly for the current application. Here is why. 

    The INA146's slew rate is rated at 0.45V/usec, this implies that the max. frequency per the 5Vp input signal is only able to handle up to 14.3kHz

    . Your customer should see triangular output at INA146 with dual supply rail, not sine wave at 50kHz. 

    Best,

    Raymond

  • 0 in reply to Raymond Zhang1
    TI__Intellectual 2830 points

    Hi Raymond, 

    which Amplifier would work better for voltage sensing here ?

    Best Regards 

    Jan

  • +1 in reply to Jan Bock
    TI__Guru 59961 points

    Hi Jan,

    What is common mode mode voltage at the output of +/-5Vpk, 50kHz of sinewave (or input of INA146)?

    The input is square wave and go through LC LP filter, which it generates 50kHz, +/-5Vpk since wave. The difference amplifier stage is converting +/-5Vpk to 0-10V, 50kHz sinewave

    Based on the calculation, a selected op amp's slew rate needs to be > 1.6 V/usec. 

    Best,

    Raymond