SLUSDL9A June 2019 – January 2021 BQ25125
The I2C interface allows the user to easily implement the JEITA standard for systems where the battery pack thermistor is monitored by the host. Additionally, the device provides a flexible voltage based TS input for monitoring the battery pack NTC thermistor. The voltage at TS is monitored to determine that the battery is at a safe temperature during charging.
To satisfy the JEITA requirements, four temperature thresholds are monitored: the cold battery threshold, the cool battery threshold, the warm battery threshold, and the hot battery threshold. These temperatures correspond to the V(COLD), V(COOL), V(WARM), and V(HOT) threshold in the Section 8.5. Charging and timers are suspended when V(TS) < V(HOT) or > V(COLD). When V(COOL) < V(TS) < V(COLD), the charging current is reduced to half of the programmed charge current. When V(HOT) < V(TS) < V(WARM), the battery regulation voltage is reduced by 140 mV (minimum VBATREG under this condition is 3.6V).
The TS function is voltage based for maximum flexibility. Connect a resistor divider from VIN to GND with TS connected to the center tap to set the threshold. The connections are shown in Figure 9-4. The resistor values are calculated using Equation 1 and Equation 2. To disable the TS function, pull TS above TSOFF threshold.