BQ25170: high and low temperature protection problem when charging

Lumina Gui

Part Number: BQ25170

Hi Sir,

Our new project imported the BQ25170 for battery charge, and found that it was quite different from the theoretical value of the specification during the high and low temperature protection testing, especially in low temperature conditions.

We hope that the low temperature protection point can be adjusted to above 0°C and the high temperature around 55°C, but found the big gap between measured value and theoretical value. After comparison, we choose 10K NTC with temperature coefficients of 3380 and 3950, and also tried to added series resistance, but none of them have solved this problem.

Can u help to find the reason of this problem? I have added our testing data and R-T comparison table to the below, hope it can do some help for problem analyse.

BQ25170 testing data.xlsx SDNT1005X103F3950FTF thermal R-T comparison table.pdf

Thanks,

Best Regards

over 4 years ago

0 Nick Brylski over 4 years ago

TI__Mastermind 19195 points

Hello Lumina,

I am taking a look into your files, you can expect a response back by the end of the week.

Thanks,

Nick

0 Nick Brylski over 4 years ago in reply to Nick Brylski

TI__Mastermind 19195 points

Hello Lumina,

I ran your NTC through a calculator for the bq25170 TS, the results are close to what you are seeing.

When determining the threshold tripoints you must also account for the tolerance on the voltage thresholds and thermistor bias current.

I have attached the calculator for your own use. Note that my result is just an estimation. For the most accurate answer you should put the min / nom / max resistance values of the NTC at each temperature into the table.

1777.TS_design_bq2517x.xlsx

Best regards,

Nick

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BQ25170: high and low temperature protection problem when charging