INA232: Measure current from a load

Stefan Sekulic

Part Number: INA232

Tool/software:

Hey,

lets say I have an output voltage from a dc/dc converter at max 20V and max I_out = 3A

How should I wire up the INA232 to measure the current through a load resistor at the output of my dc dc converter? And what shunt do i need?

19 days ago

0 Clemens Ladisch 19 days ago

Guru 285390 points

Put the shunt resistor below or above the load. (If you do not want a ground offset between the load and the rest of the system, use a high-side shunt.)

The INA232 can use a full-scale range of either 20 mV or 80 mV, so you should size the shunt resistor to generate that voltage drop for the maximum current that you want to be able to measure.

0 Stefan Sekulic 19 days ago in reply to Clemens Ladisch

Prodigy 50 points

whats the difference between 20 / 80mV range?

At I_max = 3A, what would you suggest?

+1 Louis L 19 days ago in reply to Stefan Sekulic

TI__Expert 4340 points

Stefan,

The difference in the 20mV and 80mV range is the resolution of your measurement, along with the maximum current you want to be able to measure. It's described here in section 8.1.1 of the datasheet.

I would suggest you watch our TIPL training video titled "How to choose a shunt resistor" here for help on picking your appropriate shunt resistor.

Please let us know if you have any other questions.

Louis

0 Stefan Sekulic 19 days ago in reply to Louis L

Prodigy 50 points

Thanks a lot Louis. Last question: I can read the register CURRENT and it returns a hex number? Or how can i calculate the current?

+1 Louis L 19 days ago in reply to Stefan Sekulic

TI__Expert 4340 points

Stefan,

Yes, the CURRENT register returns a HEX number, noted by the h following the reset value.

Louis

0 Stefan Sekulic 19 days ago in reply to Louis L

Prodigy 50 points

I figured 6mOhm would be appropriate for a current range from 0-3A at 22,48mV?

Greetings

+1 Louis L 19 days ago in reply to Stefan Sekulic

TI__Expert 4340 points

Stefan,

Yes, a 6mΩ resistor with a maximum current of 3A would create ~18mV drop across the shunt, which would be within the 20.48mV limit of the device (in that specific ADCRANGE = 1 setting).

Louis

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INA232: Measure current from a load