INA181: Measure loop gain with frequency analysis

Anton Morian

Part Number: INA181

Tool/software:

We have a INA181 mounted like so where +Vout and ++Vout are seperated by shunt resistors. The INA circuit measure the current just fine. The Iout signal is fed into a MCU. In my MCU I have a PID that will regulate the current, however when I try to adjust my PID values according to the bode plot I get, its like nothing changes.

My hadware connections is, I lift PIN 1 and mount a 47 Ohm resistor and inject my disturbence there. It feels like something gets saturated or I reach an upper celling. Any Ideas?

10 months ago

0 Levi DV 10 months ago

TI__Genius 10775 points

Hello,

It isn't clear to me how you are connecting the INA181 to the PID system and what is going wrong. What test are you doing with the 47Ohm resistor?

Thanks,

Levi DV

0 Anton Morian 10 months ago in reply to Levi DV

Prodigy 10 points

Its digitally controlled, so the Iout signal is fed into the MCU. I m injecting disturbence signal and measure the freq response with bode 100

0 Levi DV 10 months ago in reply to Anton Morian

TI__Genius 10775 points

I think I understand, you are breaking the feedback loop to measure the open-loop frequency response, correct? What seems to be the problem/is unexpected about the response you are receiving?

Thanks,

Levi DV

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INA181: Measure loop gain with frequency analysis