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BQ25601: Thermistor hookup and program

Daniel Brown
Intellectual 870 points
Part Number: BQ25601

The datasheet is vague hookup of thermistor and resistors for programming and how to program.
Can you provide some details on what resistors/thermistors to hook up and how to choose their"
values? Below picture for reference.

  • 0
    TI__Mastermind 25800 points
    Hey Daniel,

    I am trying to understand where you find the lack of clarity in the datasheet. Could you provide more feedback on how that section can be improved or what information is missing in view?

    I will point you to section 8.3.7.5 JEITA Guideline Compliance During Charging Mode of the datasheet in regards to selecting the proper value of RT1 (being the upper resistor) and RT2, being the lower resistor.

    The values we calculate as an example in our datasheet (both the section I referenced and the application diagram) are based on a 103AT-2 type NTC thermistor with a chosen temperature window of 0-60C, 0C being the TCOLD threshold, and 60C being the THOT threshold.

    However, in general, you may select your temperature window based on the equations provided in that section and the resistance vs temperature profile of the NTC thermistor you pick.


    Regards,
    Joel H
  • 0 in reply to Joel Hernandez II
    Intellectual 870 points
    Okay, thanks. I missed this section. Could you point me to where I can get the JEITA guideline?
    In the calculations where do the values for RTHcold and RTHhot come from? I didn't see graphs or
    tables with these values.
  • 0 in reply to Daniel Brown
    TI__Mastermind 25800 points
    Hey Daniel,

    This is section 8.3.7.5 JEITA Guideline Compliance During Charging Mode on page 21 of the datasheet.

    RTHcold is the resistance of the thermistor you choose in your design @ the TCOLD (T1) threshold you choose.
    RTHhot is the resistance of the thermistor you choose in your design @ the THOT (T5) threshold you choose.

    In the example in our datasheet, we base it on the resistance vs temperature profile of a 103AT-2 type thermistor, chose at TCOLD and THOT thresholds of 0C and 60C, respectively. At 0C, the thermistor resistance is 27.28 kOhm, and 3.02 kOhm @ 60C.

    It is important to note that certain temperature ranges will not work mathematically.


    Regards,
    Joel H