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Original question:

BQ79616-Q1: BQ79616 OT register settings

BQ79616-Q1: OTUT_THRESH register setting

Priya Nadathur
Intellectual 545 points
Part Number: BQ79616-Q1


The BQ OTUT comparators use the ratio of the (GPIO voltage/TSREF voltage) to determine OT and UT faults. For an OT_THR register setting b00000 (which is 10% from the discussion in the related link), how do I translate 10% to a temperature value? The firmware calculates the NTC value based on the GPIO voltage and TSREF voltage. These voltages are calculated applying the scale factors to the GPIO and TSREF register readings.

Thanks,

Priya

  • 0
    TI__Expert 3370 points

    Hi Priya,

    Thank you for reaching out! I am working with our team to come up with a clear answer to your question. We will respond with a confirmed answer by early next week.

    Thanks,

    Julia Louis

  • +1
    TI__Intellectual 2810 points

    Hi Priya,

    You are correct when you say that the % value is (GPIO voltage / TSREF voltage) * 100 so from here if you measure (or simply apply 5V) for the TSREF voltage you can get the GPIO voltage as well.

    In order to convert the GPIO voltage (or % value) into temperature, you will need to know your NTC parameters (Resistance at 25C, Beta coefficient, etc) and the resistor value that is used to pull to TSREF. This math is well known and there is a lot of literature about this on the web, including some calculators.

    Regards,

    Viktor.

  • 0 in reply to Viktor Tasevski
    Intellectual 545 points

    I received more thermistor data on Friday. I have the info needed to set the register. 

    Thanks