INA241A: Gain variation wrt input signal's duty cycle

Asha C

Intellectual 385 points

Part Number: INA241A

Tool/software:

Hello,

Please find the below schematic of INA241A2.

During testing , 115mV of signal was fed across IN- and IN+ at TP15 and TP17 points.

With 80% input duty cycle , we are observing output voltage reaches 2.120V where input voltage is 0.115mV (Ideally output had to be 0.115*20 which is 2.3V).

But with 20% input duty cycle , we are observing output voltage reaches 1.89V where input voltage is 0.115mV (Ideally output had to be 0.115*20 which is 2.3V)

Could you please explain why Gain is varying wrt input duty cycle and there is a lot of error in Gain.

5 months ago

0 Asha C 5 months ago

Intellectual 385 points

Please find the corrected schematic,

0 Javier Contreras4 5 months ago in reply to Asha C

TI__Mastermind 32340 points

Hello Asha,

I have two recommendations. One is the you measure the output voltage before the filter. Another is to change the input resistors do have lower values. The larger the series resistors the larger the gain error you will get due to the IB of the INA241. I would suggest 10Ω or less.

Please let me know if this helps.

Regards,

Javier

0 Asha C 5 months ago in reply to Javier Contreras4

Intellectual 385 points

Hello Javier,

To clarify , Measured output voltage is before the filter. It was measured on the output pin of opamp.

As suggested , will try reducing the input resistance to 10R, but here during testing input voltage was fed directly to the test points(at the input terminals).

Thanks!

0 Javier Contreras4 5 months ago in reply to Asha C

TI__Mastermind 32340 points

Hello Asha,

That is correct. Please let me know if this points to the issue.

Regards,

Javier

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INA241A: Gain variation wrt input signal's duty cycle