SLUAAL4 August   2022 BQ21040

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
  4. 2How Temperature Sensing Works on the BQ21040
    1. 2.1 With Adapter Present
    2. 2.2 Without Adapter Present
  5. 3Example Application
    1. 3.1 Required Devices
    2. 3.2 Setup
  6. 4Procedure
    1. 4.1 Detecting Adapter Removal
    2. 4.2 Detecting Adapter Insertion
    3. 4.3 Logical Flowchart
  7. 5Summary
  8. 6References

Abstract

Temperature sensing is a top priority in many battery charger applications. Oftentimes, accurate temperature monitoring is essential even when an adapter is not present and power is not being supplied to the charger IC. Particularly on the BQ21040, temperature sensing is handled by supplying 50uA current from the TS pin across an NTC thermistor. However, this typical mode of operation is not possible without power being supplied to the BQ21040 via an adapter at the IN pin. This application note serves to outline how TS functions at a high level and how one might use an external MCU to be able to monitor battery temperature even when an adapter is not present