SLUSEG4B December 2022 – February 2024 BQ25628 , BQ25629
PRODUCTION DATA
Refer to the PDF data sheet for device specific package drawings
The typical TS resistor network is illustrated below.
The value of RT1 and RT2 are determined from the resistance of the thermistor at 0 and 60ºC (RTH0degC and RTH60degC) and the corresponding voltage thresholds VTS_0degC and VTS_60degC (expressed as percentage of REGN with value between 0 and 1). For the most accurate thermistor curve fitting, use the rising threshold for VTS_COLD at 0ºC and the falling threshold for VTS_HOT at 60ºC, regardless of the actual register settings for TS_TH1_TH2_TH3 and TS_TH4_TH5_TH6.
Assuming a 103AT NTC thermistor on the battery pack, the RT1 and RT2 are calculated to be 5.32 kΩ and 30.1 kΩ respectively.
If the thermistor is biased from TS_BIAS, the maximum current should be checked against ITS_BIAS_FAULT. For the worst-case condition of thermistor at 0-Ω impedance (very hot), the bias current is :
For 5.30-kΩ RT1, this has a maximum IBIAS of 0.94 mA, which is well below the minimum ITS_BIAS_FAULT threshold. The 103AT NTC thermistor is the recommended thermistor and has 10-kΩ nominal impedance. Using a lower impedance thermistor will change the value of R1 and may produce a bias current that exceeds the TS_BIAS pin fault threshold. TS_STAT[2:0] is set to 111.