The I²C interface allows the user to easily implement the JEITA standard for systems where the battery pack thermistor is monitored by the host. Additionally, the BQ2416xx provides a flexible, voltage based TS input for monitoring the battery pack NTC thermistor. The voltage at TS is monitored to determine that the battery is at a safe temperature during charging. The BQ24160, BQ24160A, BQ24161B, BQ24163, and BQ24168 enable the user to easily implement the JEITA standard for charging temperature while the BQ24161 only monitors the hot and cold cutoff temperatures and leaves the JEITA control to the host. The JEITA specification is shown in.

Figure 8-4 Charge Current During TS Conditions

To satisfy the JEITA requirements, four temperature thresholds are monitored; the cold battery threshold (T_NTC < 0°C), the cool battery threshold (0°C < T_NTC < 10°C), the warm battery threshold (45°C < T_NTC ≤ 60°C) and the hot battery threshold (T_NTC > 60°C). These temperatures correspond to the V_COLD, V_COOL, V_WARM, and V_HOT thresholds. Charging is suspended and timers are suspended when V_TS < V_HOT or V_TS > V_COLD. When V_WARM > V_TS > V_HOT, the battery regulation voltage is reduced by 140 mV from the programmed regulation threshold. When V_COLD > V_TS > V_COOL, the charging current is reduced to half of the programmed charge current.

The TS function is voltage based for maximum flexibility. Connect a resistor divider from DRV to GND with TS connected to the center tap to set the threshold. The connections are shown in Figure 8-11. The resistor values are calculated using the following equations:

Equation 1.

Equation 2.

Where:

V_COLD = 0.60 × V_DRV

V_HOT = 0.30 × V_DRV

Where R_HOT is the NTC resistance at the hot temperature and R_COLD is the NTC resistance at cold temperature.

For the BQ24160, BQ24161B, BQ24163, and BQ24168, the WARM and COOL thresholds are not independently programmable. The COOL and WARM NTC resistances for a selected resistor divider are calculated using the following equations:

Equation 3.

Equation 4.

Figure 8-5 TS Circuit