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bq27510 without thermistor

Dan-o
Intellectual 895 points

I found the other post about this but still have questions. I am not using a thermistor and the datasheet doesn't do a good job of explaining the internal circuitry.

My circuit is powered from the battery only. From the reference schematic, can I drop the 1.8M, 18.2k, and 1k resistors and tie BI/TOUT to ground? I am not sure how the thermistor measurement works (and what the 1k resistor is for). Does the gauge output 2.5V on BI/TOUT and measure the voltage at TS? In this case it seems I would want to tie BI/TOUT to ground through a resistor so it doesn't short.

Can TS be left floating? Should I tie it to ground through a 10k resistor? Or should I implement all the discrete components in the reference schematic and use a 10k to ground at the "thermistor input" node?

 

  • 0
    TI__Expert 4050 points

    if you are using internal temp sensor, TS pin can be left floating, to be safe, tie a 10k to ground is better. But BI pin need to be pulled low (through 10k to ground) to force a battery detection. Gauge output 2.5V on TS pin and detect the voltage at TS pin to measure the temperature. Gauging does need temperature info to provide accurate gauging.

     

    Ming

  • 0 in reply to Ming Yu
    Intellectual 895 points

    ok thanks! I think "accuracy" without a thermistor will be degraded though. OCV on lithiums can vary 10-20% at cold temperatures so I could see that messing up the gauge a little bit.