SLUAAT7 January   2024 BQ25672 , BQ25790 , BQ25792 , BQ25798

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2IRMS Discharge Current
  6. 3External Battery FET
  7. 4Charger With PG and or Host GPIO
  8. 5Buck-only Charger
  9. 6Boosting Charger
  10. 7Summary
  11. 8References

7 Summary

Adding an external battery in parallel with an I-FET charger’s internal battery FET is an easy way to increase the charger’s battery discharge current capability. Note in all three cases, some battery current is required for the pull up resistor and, in the last case, the comparator. Choosing a PFET with high VGSmax (commonly +20 V) is also recommended. Any battery discharge current detection or protection provided by the internal battery FET is no longer valid due to the extra current flowing through the external FET. If long battery life (low leakage) is critical for the application, then a charger or charge controller with external battery FET or connecting the load directly to the battery can be better options.