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BQ25638: Different thermistor

Darren Jenkins
Genius 12511 points
Part Number: BQ25638
Other Parts Discussed in Thread: BQ25622

Tool/software:

Battery Charger team,

Our customer is considering the BQ25638 in situation where they are modifying an existing design.  They want to continue using a 47 kOhm thermistor instead of changing to a 10 kOhm.  Is there any way to do this with the BQ25638?  Or is there a different device they should select?

Thanks,
Darren

  • 0
    TI__Guru 57681 points

    Hi Darren,

    1.The RT1 and RT2 equations on the d/s are valid for other types of thermistors. Just plug in the thermistor information for the specified temperatures (HOT and COLD) accordingly.

    2,For RT1 and RT2 calculation tool, please refer to https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1209815/faq-bq25620-bq2562x-calculator-tool. The BQ25638 is similar to the BQ25622. Although it was developed for the BQ2562x, the principle is similar and can be used for BQ25638 with minor changes.

    3.If RT1 or RT2 is a negative value, then the thermistor does not work and please try another thermistor. 

    4.It’s not recommended to use >100kohm resistor values for RT1 and RT2. It may increase the TS function errors.

    5.The calculator is for reference only. Please double-check the the actual protection temperature range and temperature profile behaviors on the boards.

    Thanks a lot,

    Ning.