SLUSDK0A August 2020 – March 2021 BQ25171-Q1
The device monitors its internal junction temperature (TJ) to avoid overheating and to limit the IC surface temperature. When the internal junction temperature exceeds the thermal regulation limit, the device automatically reduces the charge current to maintain the junction temperature at the thermal regulation limit (TREG). During thermal regulation, the actual charging current is usually below the programmed value on the ISET pin. Therefore, the termination comparator for the Lithium-Ion battery is disabled, and the safety timer runs at half the clock rate.
Additionally, the device has thermal shutdown to turn off the linear regulator when the IC junction temperature exceeds the TSHUT threshold. A recoverable fault is signaled via the status pins (STAT1 = LOW, STAT2 = HIGH). The charger resumes operation when the IC die temperature decreases below the TSHUT falling threshold.