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BQ24091: BQ24091 NTC calculation related inquiries

Grady Lee
Genius 4215 points
Part Number: BQ24091
Other Parts Discussed in Thread: BQ24090

Hi, TI expert.

According to the BQ24091 datasheet, I understood that using ß=3370 out of 100K NTC would allow setting from 0 to 45°C without additional external resistors.

However, after actually calculating it, it seems that it is set to 3~41°C even if ß=3370 is used. I would like to ask you to confirm if this is correct.

Customers are also mass-producing products with BQ24090 + 10K NTC (ß=3370) applied.

If the above calculation is correct, I wonder if the actual charging set temperature is 3~41°C instead of 0~45°C even for products with BQ24090 + 10K NTC (ß=3370) applied.

Please check. Thank you.

  • +1
    TI__Prodigy 120 points

    Hey Grady,

    The values you calculated for the hot and cold thresholds are correct. This is to ensure that the device will function within a safe threshold while still accounting for various component tolerances. It's safer to be within the 0-45 degree threshold than outside. The temperature cutoff points can always be adjusted with compensation resistors to get the curve closer to the ideal value if that is preferred. 

    best,

    Hunter Adams