The TS function for the BQ24040/5 is designed to follow the new JEITA temperature standard for Li-Ion and Li-Pol batteries. There are now four thresholds, 60°C, 45°C, 10°C, and 0°C. Normal operation occurs between 10°C and 45°C. If between 0°C and 10°C the charge current level is cut in half and if between 45°C and 60°C the regulation voltage is reduced to 4.1Vmax, see Figure 8-4.

The TS feature is implemented using an internal 50μA current source to bias the thermistor (designed for use with a 10k NTC β = 3370 (SEMITEC 103AT-2 or Mitsubishi TH05-3H103F) connected from the TS terminal to V_SS. If this feature is not needed, a fixed 10kΩ can be placed between TS and V_SS to allow normal operation. This may be done if the host is monitoring the thermistor and then the host would determine when to pull the TS terminal low to disable charge.

The TS terminal has two additional features, when the TS terminal is pulled low or floated/driven high. A low disables charge (similar to a high on the BAT_EN feature) and a high puts the charger in TTDM.

Above 60°C or below 0°C the charge is disabled. Once the thermistor reaches ≉–10°C the TS current folds back to keep a cold thermistor (between –10°C and –50°C) from placing the IC in the TTDM mode. If the TS terminal is pulled low into disable mode, the current is reduce to ≉30μA, see Figure 8-2. Since the I_TS curent is fixed along with the temperature thresholds, it is not possible to use thermistor values other than the 10k NTC (at 25°C).