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INA901-SP: Usable range for I*R current sensing of low voltage supplies

Chris Belting
Prodigy 50 points
Part Number: INA901-SP

As I read the datasheet, current sensing of I*R less than 20mV cannot be expected for low voltage supplies when VCM is less than or equal to VS, the supply voltage (Section 7.4.2.4).

Is that correct?

I am trying to evaluate using the part for low voltage supplies (3.3V, 2.5V 1.8V, 1.5V) that are more sensitive to series voltage drops and can have a wider range of operating currents. If my understanding is correct it would limit the useful application to 20mV < I*R < Vmax, where Vmax is the highest voltage drop that can be tolerated for the power supply output.

If true I will need to look for other 50kRad tolerant options.

Thanks

  • 0
    TI__Mastermind 18780 points

    Chris, 

    Yes, unfortunately, this is the case. For the INA901, the minimum sense voltage recommended is 20mV. The upper range may be allowed to scale to within 200mV of the supply voltage, but typically best performance is seen inside the 20mV to 100mV window. What level of burden voltage are you looking to limit to here?

  • 0
    Prodigy 50 points

    For the lower output voltages 50mV is still significant and 100mV is greater than 5% of the output voltage. 

    There are other options like putting the current sense on the input-side of regulators but this won't work when the output voltage is supplied by a multi-output switching regulator.

    Thanks for the verifying my concern.