ZHCSJD3B July 2018 – February 2019 BQ25150
During operation, to protect the device from damage due to overheating, the junction temperature of the die, TJ, is monitored. When TJ reaches TSHUTDOWN the device stops operation and is turned off. The device resumes operation when TJ falls below TSHUTDOWN by THYS.
During the charging process, to prevent overheating in the device, the device monitors the junction temperature of the die and reduces the charging current at a rate of (0.04 x ICHARGE )/°C once TJ exceeds the thermal foldback threshold, TREG. If the charge current is reduced to 0, the battery supplies the current needed to supply the PMID output. The thermal regulation threshold may be set through I2C by setting the THERM_REG bits to the desired value.
To ensure that the system power dissipation is under the limits of the device. The power dissipated by the device can be calculated using the following equation:
The die junction temperature, TJ, can be estimated based on the expected board performance using the following equation:
The θJA is largely driven by the board layout. For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report SPRA953. Under typical conditions, the time spent in this state is very short.