7.4.4 Thermal Shutdown

Rechargeable Li-ion batteries need protection from damage due to operation at elevated temperatures. The application should provide this battery protection and ensure that the ambient temperature is never elevated greater than the expected operational range of 85°C.

The bq25570 uses an integrated temperature sensor to monitor the junction temperature of the device. Once the temperature threshold is exceeded, the boost charger and buck converter are disabled. Once the temperature of the device drops below this threshold, the boost charger and buck converter resume operation. To avoid unstable operation near the overtemperature threshold, a built-in hysteresis of approximately 5°C has been implemented. Care should be taken to not over discharge the battery in this condition since the boost charger is disabled. However, if the supply voltage drops to the VBAT_UV setting, the switch between VBAT and VSTOR will open and protect the battery even if the device is in thermal shutdown.