SLUSAH0F October 2011 – November 2019 BQ25504
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 BQ25504 uses an integrated temperature sensor to monitor the junction temperature of the device. If the OT_PROG pin is tied low, then the temperature threshold for thermal protection is set to TSD_ProtL which is 65°C typically. If the OT_PROG is tied high, then the temperature is set to TSD_ProtH which is 120°C typically. Once the temperature threshold is exceeded, the boost converter/charger is disabled and charging ceases. Once the temperature of the device drops below this threshold, the boost converter and or charger can resume operation. To avoid unstable operation near the overtemp 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 converter/charger is disabled. However, if the supply voltage drops to the VBAT_UV setting, then the switch between VBAT and VSTOR will open and protect the battery even if the device is in thermal shutdown.