JAJSKU9B December 2022 – February 2024 BQ25628 , BQ25629
PRODUCTION DATA
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.