While charging, the device continuously monitors battery temperature by sensing the voltage at the TS pin. A negative temperature coefficient (NTC) thermistor should be connected between the TS and GND pins (recommend: 103AT-2). If temperature sensing is not required in the application, connect a fixed 10-kΩ resistor from TS to GND to allow normal operation. Battery charging is allowed when the TS pin voltage falls between the V_COLD and V_HOT thresholds (typically 0°C to 45°C). Charging current is reduced to 20% of the programmed ISET value when V_COLD > TS > V_COOL (typically 0°C to 10°C). The charging profile can be seen in Figure 7-3.

Figure 7-3 BQ25175 Charging Profile

If the TS pin indicates battery temperature is outside this range, the device stops charging, enters the STANDBY state, and blinks the STAT pin. Once battery temperature returns to normal conditions, charging resumes automatically.

In addition to battery temperature sensing, the TS pin can be used to disable the charger at any time by pulling TS voltage below V_{TS_ENZ}. The device disables the charger and consumes I_{SD_IN_TS} from the input supply. In order to minimize quiescent current, the TS current source (I_{TS_BIAS}) is duty-cycled, with an on time of t_{TS_DUTY_ON} and an off time of t_{TS_DUTY_OFF}. After the TS pin pulldown is released, the device may take up to t_{TS_DUTY_OFF} to turn the I_{TS_BIAS} back on. After the source is turned on, the TS pin voltage will go above V_{TS_EN}, and re-enable the charger operation. The device treats this TS pin toggle as an input supply toggle, triggering a device power up from input source (see Section 7.3.1).