INA260: Current register reading is always -1.250000, even though I'm measuring 0.42mA with ampermeter value

M. Awal Mamouda

Part Number: INA260
Other Parts Discussed in Thread: INA210, TIPD135, TIPD156, TIPD104, TIPD129

Hello,

I hope someone would help me solving that issue:

For checking the I2C communication between the MCU and the INA260 , I write (0x63FF) to the configuration register and read it back and get 0x63FF. So, it's working.
Now, I read th Manufacturer ID and I get 0x5449. This is correct, too.

From the current register I'm reading -1.250000.
I measured the current through the shunt resistor and i's 0.42mA or 0.22mA depending on the resitistor in series with the LED.

Thanks for your help
Awal

over 6 years ago

0 Peter Iliya over 6 years ago

TI__Mastermind 26710 points

Hello Awal,

Thanks for choosing TI. Are you reading -1.25mA or -1.25A? The INA260 has an input offset current (Ios) of +-1.25mA typical (+-5mA maximum), which means you cannot expect the device to measure any current less than 5mA. In fact you cannot expect any reasonable accuracy for current less than 50mA. If current is 50mA, the INA260 measurement will have typically 2.5% error (10% error maximum) and this error is exclusively due to input offset current.

Sincerely,
Peter Iliya
Current Sensing Applications

0 M. Awal Mamouda over 6 years ago in reply to Peter Iliya

Prodigy 50 points

Hello Peter,

thanks a lot for your quick reaction.

In fact, I'd like to measure currents having 30mA max.
So, now I understand, I cannot use the INA260.

So, which solution would you propose for measuring currents from 0 - 30 mA ?

Best regards

Awal

0 Peter Iliya over 6 years ago in reply to M. Awal Mamouda

TI__Mastermind 26710 points

Hello Awal,

You could look at the INA210. You will want a device with the lowest input offset (Vos) as possible. You can also refer to one of these designs as well for more ideas.

TIPD135 - 10uA-100mA, 0.05% Error, High-Side Current Sensing Solution Reference Design
http://www.ti.com/tool/TIPD135

TIPD156 - Low-Drift Bidirectional Single-Supply Low-Side Current Sensing Reference Design
http://www.ti.com/tool/TIPD156

TIPD104 - Current Sensing Solution, 10uA-10mA, Low-side, Single Supply
http://www.ti.com/tool/TIPD104

TIPD129 - 0-1A, Single-Supply, Low-Side, Current Sensing Solution
http://www.ti.com/tool/TIPD129

Here's a little article discussing error with low current measurments:
e2e.ti.com/.../3593.how-vos-and-ib-affect-small-current-measurements

Sincerely,
Peter Iliya
Current Sensing Applications

0 M. Awal Mamouda over 6 years ago in reply to Peter Iliya

Prodigy 50 points

Hello Peter,

thanks a lot for your help !

Best regards
Awal

Amplifiers

Amplifiers forum

INA260: Current register reading is always -1.250000, even though I'm measuring 0.42mA with ampermeter value