SLUSC88C March 2015 – October 2022 BQ25895
PRODUCTION DATA
The device continuously monitors battery temperature by measuring the voltage between the TS pins and ground, typically determined by a negative temperature coefficient thermistor (NTC) and an external voltage divider. The device compares this voltage against its internal thresholds to determine if charging is allowed. To initiate a charge cycle, the battery temperature must be within the VLTF to VHTF thresholds. During the charge cycle the battery temperature must be within the VLTF to VTCO thresholds, else the device suspends charging and waits until the battery temperature is within the VLTF to VHTF range.
When the TS fault occurs, the fault register REG0C[2:0] indicates the actual condition on each TS pin and an INT is asserted to the host. The STAT pin indicates the fault when charging is suspended.
Assuming a 103AT NTC thermistor on the battery pack as shown in Figure 8-6, the value RT1 and RT2 can be determined by using Equation 2:
Select 0°C to 45°C range for Li-ion or Li-polymer battery,
RTHCOLD = 27.28 kΩ
RTHHOT = 4.91 kΩ
RT1 = 5.21 kΩ
RT2 = 29.87 kΩ