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Original question:

INA250: Mesuring motor current with INA250 amplifier

INA185: Current Sense Applications for 0.1 to 1.0 A with high resolution

Florian Mayerle
Prodigy 60 points
Part Number: INA185
Other Parts Discussed in Thread: INA190, INA250, INA253

Hi, 

can anyone recomment an INAxxx shunt monitor fur current sensing in range of 
power supply: 2.7 to 5V

Which value for the shunt would be apprperiate and is there a solution with a integrated shunt?
I tried already the INA250A4 but the output with 5V supply has a high offset.

Thanks Flo

  • 0
    TI__Mastermind 21730 points

    Hey Florian,

    Thanks for considering to use Texas Instruments, If input offset is a big concern, I would recommend the INA190 as among our portfolio has one of the lowest offsets as well as one of the lowest input bias currents.  To further reduce the error from offset without calibration will require you to increase your shunt resistance.  To maximize the shunt resistance you need to use the lowest gain and full sensing range of the device.  So if you used the INA190, you could calculate the shunt by: (Vcc - swing to VCC)/gain/Load Max= (5V-0.04V)/(25V/V)/(1 A)=0.1984.  From there you would choose the nearest purchasable shunt size beneath that.  On digikey I found 198mohm resistor, but you might get a better price with a 190mohm.  Assuming we use the 198mohm shunt, your max offset error found at the minimum load would be: (Vos max)/(shunt x load min)*100% = (15uV)/(0.1A*0.198ohm)*100%=0.075%.

    As for devices with an integrated shunt, the only other alternative we offer from the INA250 is the INA253.