INA226: Sensing current from 35uA to 1mA

Jesus Adrian Guerra Delgado

Part Number: INA226
Other Parts Discussed in Thread: MSP430FR6047, , INA236, INA238, INA228

Tool/software:

Hi I've been trying to measure a very small current, this is from the MSP430FR6047 in LMP3.5 rest mode, this current is in micro ampers. I get to this amplifier because it has a max 10uv offset, so I just want to be sure before start the experiments, my current goes from 35uA to 1mA.

Thanks for your help, sorry my english

4 months ago

0 Clemens Ladisch 4 months ago

Guru 276380 points

And what is your question?

0 Jesus Adrian Guerra Delgado 4 months ago

Prodigy 50 points

If the INA226 can measure that range

0 Clemens Ladisch 4 months ago in reply to Jesus Adrian Guerra Delgado

Guru 276380 points

This device measures the voltage drop over the shunt resistor. It can measure any range, as long as the resistor is sized correctly.

In general, you want the resistor to be as large as possible so that the error is much smaller than the signal. But you have to ensure that the maximum voltage drop is still small enough to not affect your actual circuit. For example, if you want a maximum voltage drop of 50 mV, the resistor is 50 mV / 1 mA = 50 Ω, and for the minimum current, the voltage would be 35 µA × 50 Ω = 1750 µV.

(The more modern INA236 is better and cheaper.)

0 Mitch M 4 months ago

TI__Mastermind 21335 points

Thanks Clemens.

Hey Jesus,

In addition to what Clemens said, when measuring very small currents you'll want a device with as small input bias current as possible. Our newer devices (such as the INA236 or INA228/INA238) would be better for this application.

Regards,

Mitch

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INA226: Sensing current from 35uA to 1mA