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BQ2980: How to use an external PTC for undertemperature and overtemperature detection

user_0815
Prodigy 70 points
Part Number: BQ2980

Hi,

I would like to use the bq298000 IC to protect my 1 cell li-ion battery pack. In the datasheet, the UT and OT feature via CTR pin is mentioned, but not not explained. How can I use this feature and how to select a fitting PTC?

Best regards!

Pascal Schröer

  • 0
    TI__Genius 10370 points

    Pascal,

    Below is a snippet taken from the bq2980 Datasheet section 8.3.8. If this does not contain enough detail please let me know. High level you can chose which pull-up based on the PTC you chose. From there you can add resistors to "tune" the device based on the temperature you would like to trigger on. 

    Thanks,

    Eric Vos

  • 0 in reply to Vos
    Prodigy 70 points

    Eric,

    if I got it right, I have to search for a device with an integrated Pull-up resistor (PTC config), right? Where can I find such a device in the "device configuration option" table. I only see devices with CTR configurations.

    The next question is how to determine the right PTC value. Do I have to calculate a voltage divider between the integrated pull-up resistor and the external PTC? Is the highlighted voltage V_IH + (V_HYS) the voltage when the divice turns off the CHG and DSG output?