INA240: current sense amplifiers have large output noise

Shawn Yang

Part Number: INA240

Currently used INA240 and INA241 current sense amplifiers have large output noise (the power supply and reference source have been confirmed to be normal) problems that affect the accuracy of current detection, and I apply for TI related technical support and the recommended selection of new models of high-precision current sense amplifiers, thank you

over 1 year ago

0 Javier Contreras4 over 1 year ago

TI__Mastermind 26485 points

Hello Shawn,

Can you please state the nature of your noise issue and describe it more. Understanding the root cause would help in determining why the INA240 or INA241 will not work for you. Could the noise come from the input. Can you provide a scope shot of the expected result vs the INA240 or INA241. A schematic and expected behavior. The more you can provide the better we can assist.

0 Shawn Yang over 1 year ago in reply to Javier Contreras4

TI__Intellectual 1285 points

This is the AD value obtained from the test amplifier output when the input of the INA240A2 is directly short-circuited, and the ripple is very large.

0 kai klaas69 over 1 year ago in reply to Shawn Yang

Guru 140200 points

Hi Shawn,

but why let you the inputs of INA240 float? The INA240 is not designed to work that way. The input bias current of INA240 must find a low ohmic path to signal ground which is impossible in your test circuit.

Kai

0 Javier Contreras4 over 1 year ago in reply to kai klaas69

TI__Mastermind 26485 points

Hello Shawn,

You can place a VCM at the input of the INA240 with the input shorted to anything from -4V to 80V. Like Kai stated you cannot leave the inputs shorted but floating with no current flow/common mode voltage.

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INA240: current sense amplifiers have large output noise