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Internal temp sensor on bq27501

Other Parts Discussed in Thread: BQ27501


   I am having problems configuring my bq27501 to use the internal temp sensor. I have left the TS pin floating, however this should not be a problem since I dont intend to use the external sensor.

When I look at the Operations config flags, TEMPS flag is red... Does this mean that it is configured for external sensor.

I am reading temperature values of 190 degrees when I am at room temperature.

I am trying to change this setup using BQEASY but it does not seem to change...


Best regards

   Roger Yttervik

  • Roger,

    if the TEMPS bit is set (red), then this means that the gauge is configured to use the external temperature sensor, so it is not surprising that you are reading a very low value.

    Changing the value in bqEASY will only take effect if you elect to program the data flash values after step 2H.  Before you do this, I also recommend that you reprogram the gauge with the default image in step 1.

    On the other hand, it may be simpler to just perform a direct data flash write. You will need to write the "Operation Configuration" word in data flash (Not in the data RAM screen).  Clear the LSB.

    After you do one of the above, reset the gauge so that the changes can take effect.  You should see that the TEMPS bit is cleared (green).

    One other note: we recommend pulling the TS pin to ground with a 10K resistor to remove any potential noise from this analog input.  Also, you should make sure that the gauge is properly detecting battery insertion properly with the BI/TOUT pin.  The functionality of this pin is described on page 24 of the data sheet.

    Let me know if this helps,


  • Hi Charles

      Thanks very much for your detailed answer :-) After coming to work today, I suddenly found that there was no longer any problem changing to internal temp sensor.

    After a little experimenting and reading the datasheet, I found that the "Voltage" was dangerously close to "Flash Update OK voltage".

    I have now reduced the value of the "Flash Update OK voltage" and things seem to be responding as expected :-)

    Thanks again