INA240: A question about INA240 output capacitive load

Peace

Part Number: INA240

Hello,

We are using INA240A2 to measure motor current. However, per the datasheet, the INA240A2 output maximum capacitive load should be limited to 1nF. So, we added a buffer in front of a 20Hz low-frequency filter. My question is to find out if it is necessary to have the buffer in front of the filter to limit the capacitive load even though a resistor is located at the output. I've attached the schematic for your reference. I would appreciate it if you could respond to me promptly.

Best regards,Attachment.docx

over 7 years ago

0 Guang Zhou over 7 years ago

TI__Mastermind 36640 points

Hi,

I think it is fine to remove the highlighted buffer; the INA240 output should still be stable.

Regards, Guang

0 kai klaas69 over 7 years ago

Guru 140200 points

Hi Peace,

why are you using a 200MHz OPAmp to build a 20Hz low pass filter??

Kai

0 Peace over 7 years ago in reply to kai klaas69

Intellectual 420 points

Hi Kai,

Thanks for your question. What would you recommend?

0 Peace over 7 years ago in reply to Guang Zhou

Intellectual 420 points

Hi Guang,

Thanks for your help!

Best regards,

0 Genatco over 7 years ago

Guru 56378 points

Hi Peace,

Seemingly the 240 capacitive loading the output signal is guaranteed to be <1nf without causing sustained ringing. Agree the way it is written could be taken to infer output should not be loaded >1nf or ringing could occur.

0 Peace over 7 years ago in reply to Genatco

Intellectual 420 points

Thanks, BP101!

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INA240: A question about INA240 output capacitive load