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INA126UA/2K5 Signal acqusition

john muchiri
Prodigy 20 points
Other Parts Discussed in Thread: INA126

Hi,

Am using INA126UA/2K5 instrumentation amplifier for bridge signal acquisition (load cell). when i use both the amplifier and a microcntroller ADC using separate powers i get the readings without any problem.

The problem arises when i use same power source for both the amplifier and the microcontroller, that is, the signal becomes distorted and cant get the correct readings. what might be the problem.

Please help. Thank you  in advance.


 

  • 0
    TI__Genius 12335 points

    Hi John,

    It's possible that the microcontroller is introducing significant noise into the power supply which is affecting the operation of the INA126. Alternatively, if you are using separate grounds for the microcontroller and the INA126, they may be at 2 different potentials which would interfere with the measurement.

    It would be helpful if you could provide a schematic of the system for us to review and also any oscilloscope screenshots you have of the distortion on the output of the INA126.

  • 0 in reply to John Caldwell
    Prodigy 20 points

    Hi john,

    i currently dont have any schematics as i have been referring the application schematics in the INA126 datasheet on single power supply.( fig 4).

    Maybe in details, am having a problem only when i use same power for the load cell, INA126 and the microcontroller.

    Initially i had used load cell and INA126 using same power and the microcontroller on a different power source and i got the readings without any problem.

  • 0 in reply to john muchiri
    TI__Genius 12335 points

    John,

    What is the power supply voltage (or voltages if you are using a dual supply) that you are using? Did the supply voltage remain the same when  you switched to 1 supply for all parts? Also, are you applying a voltage to the reference pin as shown in figure 4 of the datasheet (REF1004C-1.2)?