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INA226: small negativ voltage measurement

Part Number: INA226
Other Parts Discussed in Thread: TIDA-00313


I want to use the ina226 chip to measure the current and voltage of a voltage source that varies from -1.5V to -3V.

The digital part (I2C microcontroller) is supplied with a voltage of 3.3V.

I have seen the different discussions in the forum but I have not been able to find a solution to my problem. You can see the circuit below.

My first question is, can I use this chip in this case? I have seen the TIDA-00313 example, the problem in my case is that the voltage to be measured can be -1.5v, that is, that voltage cannot be used as a power supply VS for ina226.

Do you have any idea how I can do this measurement?

Thank you,


  • Hello Oscar,

    Thank you for using the TI forum. You should still be able to use the concept of TIDA-00313 to get this done if you use spit "GND_ISO" into two different nodes. "The GND_ISO1" would replace the GND_ISO that connects to the  VBUS and Shunt, which would be your 0V, and your "GND_ISO2" would be a separate isolated voltage for the VS+  and VCC2 side. This would need to be at least a couple volts so that it could be used with the Zener to power the device. (it would just need to be a different supply than the VCC1 for isolation. Then your "GND_INA" would be the negative voltage.