data/text/DLP2/753020

[FAQ] BQ24040 and BQ2404X family Charge Complete Pin Behavior, /CHG

The BQ2404X family of charger has a charge complete pin, /CHG to indicate charge in progress or complete. But under some conditions the battery charge has stopped (no current to battery) but /CHG indicates charge. In other case the battery is charging (current to battery) but /CHG does not indicate charge in progress.

This also applies to BQ21040, BQ24050, BQ24090 and BQ25100 family of devices. The /CHRG pin in an open drain output used to indicate that a battery charge cycle is in progress. The pin will go low when the device detects a valid power supply and starts charging the battery. The pin will go high impedance when the device detects that the battery is fully charged (Change Complete/ Termination). In order to optimize end user experience the charger behavior under the particular cases below is as follows: 1.) If TS (NTC) pin indicates an over temp condition charge is suspended, but the /CHG pin will remain low since termination or charge complete has not been detected. Charge will resume when temp is reduced and the /CHG pin will remain low. 2.) The BQ2404X will automatically restart charge if after termination/charge complete the battery voltage drops to Recharge (V-RCH). This is done to maintain the battery fully charged. In this case the /CHG pin will remain high-Z after termination even if the recharge has started. 3.) During OVP shutdown or Charge Timer Fault /CHG is high –Z Note on First Charge Cycle-- will start when power is applied, disable / enable using TS pin or detect battery insertion, /CHG is low. Start charge cycle but not First charge cycle exiting TTDM mode or battery voltage below V-RCH. Additional info see BQ24040 Data Sheet Charge Complete Data Sheet section 8.3.7 also see Table in section 8.4.1. Note -- Updated section 2 May 20, 2019 -- To remain high-Z