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INA128: Amplifier output value varying

raj eg
Prodigy 230 points
Part Number: INA128

Dear sir,

Good day.

We are using the Instrumentation amplifier INA128 our application is used to measure the strain gauge output (mv).

So we are using the gain factor 250 value and measure the mv to v.

Our maximum output is 10mv is converted to 2.5V.

Every time we power OFF and ON the amplifier INA128 circuit the output value is varying.

Example (we are given know voltage from source meter 1mv and output of INA128 amplifier  we getting 240mv, 269, 256,241,275,238,etc,,, every time power OFF/ON the output voltage varying on everytime.

Please do the needful.

please find the attached schematic for amplifier circuit and power from dc to dc converter.

NOTE not populate the capacitor C253 ,C254, c251 &c256

  • 0
    TI__Genius 10850 points

    Hi Raj,

    Thanks for your post, I can help you.

    The INA128 should not be sensitive to power supply sequencing or toggling, although it does have a settling time specification:

    I do have some questions for you:

    • How are you generating the 1mV input signal?
    • How are you measuring the output of the INA128? 
    • Are you continuously measuring the output? Does it eventually settle to the expected value? 

    You may consider adding a low-pass filter on the output of the amplifier (approximately at 50kHz).