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Original question:

BQ25619: I have feww question about BQ25619

BQ25619: NTC parameter check

Will Wang47
Expert 7750 points
Part Number: BQ25619

Hi team,

Customer want to use BQ25619 in there project, they get one question about the temperature protection feature.

In there application, the NTC is inside their battery, and it's full part number is "NCP03WF104F05RL NTC SMD 0201 100KΩ±1% B25/50=4250 ±1% Murata". This is different from our datasheet test data used NTC 103AT. So they want to check with us, if the JEITA THERMISTOR COMPARATOR (CHARGE MODE) threshold data could also with for the NTC they use?

https://www.murata.com/en-us/products/productdetail?partno=NCP03WF104F05RL

Best Regards,

Will

  • 0
    TI__Genius 10385 points

    Will,

    I would be able to help you calculate appropriate RT1 and RT2 values for this thermistor, but I will need you to provide the resistance value of the NTC at T1 and T5.

    Thanks,

    Ricardo

  • 0 in reply to Ricardo
    TI__Expert 7750 points

    HI Ricardo,

    Thanks for helping calculate the RT1 and RT2. T1 resistor is 357.0117kohm, T5 resistor is 22.2243kohm, 

    Customer also cares about if the threshold values listed on the datasheet could be used for all thermistor, since the test condition mention that this data is tested using 103AT thermistor. I hope my explanation is clear.

    Best Regards,

    Will

  • 0 in reply to Will Wang47
    TI__Genius 10385 points

    Will,

    RT2 = 141.7812kohm -> 142kohm @ 0.1%,0.25%,0.5%

    RT1 = 36.96478kohm - > 37kohm @ 0.1%,0.25%,0.5%

    It does not necessarily have to be 103AT, but this thermistor the IC was defined for and the thermistor we warranty performance with. Please follow up with the customer and ensure all is well with this configuration.

    Thanks,

    Ricardo

  • 0 in reply to Ricardo
    Prodigy 20 points

    Ricardo,

    Thanks for your support.

    But, calculated according to the formula in the specification, The result of my calculation is RT1=36.96k, RT2=142k.

    Is there some misunderstanding?

    BTW, I would like to know the accuracy of temperature detection of BQ25619. 

  • 0 in reply to user6249998
    TI__Genius 10385 points

    Will,

    36.96k is not a standard resistor value, so I rounded to the nearest actual value.

    Based on these real values TS ADC would be 73.3% at 0.89C and 34.2% at 59.59C.

    Please check your E2E inbox as I would like discuss this with you in further detail.

    Thanks,

    Ricardo