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LMP90100 Current Source Compliance Range

Moha Deeb1
Intellectual 270 points
Other Parts Discussed in Thread: LMP90100, REF200

Hi,

In the LMP90100 datasheet, current source characteristics compliance range for IB1/IB2 is VA-0.8.

If I wanted to use the current source to measure resistance (NTC) and set VA=5V, IB1=100uA, I can't measure R > 42K due to this.

is there a way around it? other than using external current source with higher compliance voltage range like REF200

Thanks,

Moha.

  • 0
    TI__Genius 16890 points
    Hello Moha,

    You are correct. Using it the way you describe, you can't measure a NTC over 42k.

    To get around this you could put a resistor in parallel with the NTC. The value of the parallel resistor would depend on the the resistance range of the NTC. You would set it so that the parallel combination does not go above about 40k ohm. From the voltage measured across the parallel combination of the resistor and NTC, you can calculate the resistance of the NTC.

    Mike