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Bq20z95 without thermistors

allen kitchen
Intellectual 320 points
Other Parts Discussed in Thread: BQ20Z90

we are using the Z95 for the first time, and we were not planning on using thermistors in the design.  Are there any problems with that?  Looking at the literature it seems the chip will want to blow the fuse and lock up if the thermistors are not present.  Can that be disabled?  

  • 0
    TI__Guru* 76230 points

    Hello Allen,

    I would suggest you connect a 10k resistor in place of the thermistors to avoid having the pin exposed to esd or the gauge reading extreme temperatures due to open thermistor thereby triggering a permanent failure. Bear in mind that for optimal gauging accuracy, the z95 IT algorithm takes into consideration the temperature. Removing the thermistors may cause your state of charge measurements to be off at extreme temperatures. 

    If you decide to go with the 10k resistor option, you should set the timers for the temperature triggers such as SOT chg time, SOT dsg time, Open time to zero to disable the corresponding functionalities. Refer to the technical reference manual of the device for more info.

    thanks

    Onyx

  • 0
    Intellectual 380 points

    allen kitchen said:
      Can that be disabled?

    Use the internal thermistor.

    1. DataFlash Screen

    2. Configuration Tab

    3. Operation Cfg A  - press right mouse button on Unit "flg", then select "Help"

           Temp1,0  [4,3]: These bits are used to tell the bq20z90 the temperature sensor configuration.  The bq20z90 can use up to 2 external sensors and there is also an internal sensor available if needed.  All of these sensors are able to use various configurations to report temperature in the Temperature register.
    • 1,1 =  The Average of TS1 and TS2 external inputs are used to generate Temperature
    • 1,0 =  Greater Value of TS1 and TS2 external inputs are used to generate Temperature
    • 0,1 =  Only Temperature sensor TS1 is used to generate Temperature
    • 0,0 =  Only internal temperature sensor is used to generate Temprature.