INA2191: Reading current within 4-20mA circuit

Cosmin Briceag

Part Number: INA2191

Hello,

I designed a circuit to read the current of a pressure sensor (4-20mA standard) and I connected the sensor as depicted in the attached picture but all the time the ADC value is zero.

Best Regards,

Cosmin Briceag

over 2 years ago

0 kai klaas69 over 2 years ago

Guru 140200 points

Hi Cosmin,

this can happen when the sensor circuit and the INA2191 are totally floating against each other.

Connect the sensor ground to the ground of your INA2191 circuit.

Kai

0 Cosmin Briceag over 2 years ago in reply to kai klaas69

Prodigy 160 points

Hello Kai,

Thanks for your help.

The sensor and power supply already have a common GND. On other ports the ADC reads 5V which seems that op-amp is saturated. I do not know if the port is broken or the sensor itself is broken.

Best Regards,

Cosmin

+1 kai klaas69 over 2 years ago in reply to Cosmin Briceag

Guru 140200 points

Hi Cosmin,

I would create a simple test circuit: Connect "S+" to +5V and "S1-" and "S2-" through a 250R resistor each to GND. Then you should see a 4V output voltage. Don't connect the voltmeter directly to the output pin of INA2191 but insert a 100...220R isolation resistor first. Disconnect the ADC input during the test.

If the problems persist, take a fresh INA2191 and remove diodes D1...D4. By the way, what clamping diodes are you using?

Kai

0 Cosmin Briceag over 2 years ago in reply to kai klaas69

Prodigy 160 points

Hello Kai,

Well, I did some measurements the the voltage is as expected. It seems that I wrongly configured the ADC ,altought there's a voltage on ADC pin the conversion result is zero.

Thank you very much for your help.

Best Regards,

Cosmin

0 kai klaas69 over 2 years ago in reply to Cosmin Briceag

Guru 140200 points

Good to hear that the INA2191 is running properly.

Good luck

0 Castrense Nigrelli over 2 years ago in reply to kai klaas69

TI__Expert 4720 points

Thank you Kai for supporting Cosmin.

Cosmin, if you have any other questions please reply.

Regards,

Cas

0 Cosmin Briceag over 2 years ago in reply to Castrense Nigrelli

Prodigy 160 points

Hello,

Thank you very much for your support!

I'll come back as soon as I'll have other topics :).

Best Regards,

Cosmin

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INA2191: Reading current within 4-20mA circuit