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BQ40Z50-R1: NTC sensor calibration

Chul woo Park
Prodigy 205 points
Part Number: BQ40Z50-R1
Other Parts Discussed in Thread: BQ40Z50

Hi,

I'm using external NTC sensor(103AT-4-70374)

and I tested sensor accuracy by comparing actual sensor and measured by NTC sensor in BQ40Z50-R1.

I measured temperature at 5 point, and I found that temperature is exact at 25C, but slope is not enough.

For example,

At 60 Degree, temperature measured by NTC is 56.4 Degree.

At 90 Degree, temperature measured by NTC is 82 Degree.

So I need to change the temperature gain. in BQ40Z50, how can I change the temperature gain?

I attached the test result.

Thanks.

  • 0
    TI__Guru* 76230 points
    Hi Chul,
    At higher temperatures the thermistor accuracy reduces. Your battery will not be properly functional at temperatures higher than 65 degrees anyway else you you will thermal runaway so the accuracy at temperatures closer to and below room temp is what is critical.
    If you still feel the need to adjust the thermistor coefficients, you can follow the app note below.
    www.ti.com/.../slua398
    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Prodigy 205 points
    Hi, I saw that slua398 doc, but my question is, there is no such a coefficient parameter on BQ40Z50-R1. Can you point out what resistor is exactly matched to temperature coefficient on BQ40Z50-R1 parameter ? There is only internal sensor parameters.