INA240: Output fluctuation

Kengo.Y

Part Number: INA240

Hi team,

The output of my customer's waveform fluctuates as follows.

CH2(BLUE) : INA240 output
CH3(PURPLE) : IN-
CH4(GREEN) : IN+

Why does it fluctuate?
How can I prevent this?

Sincerely.
Kengo.

over 5 years ago

0 kai klaas69 over 5 years ago

Guru 140200 points

Hi Kengo,

this is caused by the finite CMRR of INA240. See also figures 21 and 22 of datasheet.

Kai

0 Kengo.Y over 5 years ago in reply to kai klaas69

Guru 11495 points

Hi Kai,

Thank you for your comment.
Is it possible to improve responsiveness?
And Is there anything other than the device that makes it less responsive?
Ex）Wiring distance or Capacitor

Sincerely.
Kengo.

0 Guang Zhou over 5 years ago in reply to Kengo.Y

TI__Mastermind 36530 points

Hi Kengo,

Like Kai mentioned, the output fluctuation is due to the common mode step. It would have been much worse if a different device was used which is not equipped with PWM rejection.

The fluctuation can’t be prevented completely. Matching input traces is important in minimizing it. As far as I can tell, what's observed largely agrees with what’s expected.

Regards, Guang

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INA240: Output fluctuation