ZHCSJD3B July 2018 – February 2019 BQ25150
The BQ25150 monitors the TS voltage and sends an interrupt to the host whenever it crosses the VHOT, VWARM, VCOOL and VCOLD thresholds which correspond to different temperature thresholds based on the NTC resistance and biasing. These thresholds may be adjusted through I2C by the host. The device will also disable charging if TS pin exceeds the VTS_OPEN threshold.
The TS biasing circuit is shown in Figure 20. The ADC range is set to 1.2 V. Note that the respective VTS and hence ADC reading for TCOLD (0°C), TCOOL (10°C), TWARM (45°C) and THOT (60°C) changes for every NTC, therefore the threshold values may need to be adjusted through I2C based on the supported NTC type.
The BQ25150 supports by default the following thresholds for a 10KΩ NTC
For accurate temperature thresholds a 10K NTC with a 3380 B-constant should be used (Murata NCP03XH103F05RL for example) with a parallel 10K resistor. Each threshold can be programmed via I2C through the TS_COLD, TS_COOL, TS_WARM and TS_HOT registers. The value in the registers corresponds to the 8 MSBs in the TS ADC output code.