8.3.7.4.1 JEITA Guideline Compliance in Charge Mode

To improve the safety of charging Li-ion batteries, JEITA guideline was released on April 20, 2007. The guideline emphasized the importance of avoiding a high charge current and high charge voltage at certain low and high temperature ranges.

To initiate a charge cycle, the voltage on TS pin must be within the VT1 to VT5 thresholds. If TS voltage exceeds the T1-T5 range, the controller suspends charging and waits until the battery temperature is within the T1 to T5 range. At cool temperature (T1-T2), JEITA recommends the charge current to be reduced to half of the charge current or lower. At warm temperature (T3-T5), JEITA recommends charge voltage less than 4.1V / cell.

On BQ25883, the charger provides flexible voltage/current settings beyond the JEITA requirement. The voltage setting at warm temperature (T3-T5) can be VREG, 8.0V, 8.3V, or charge suspend (configured by JEITA_VSET [1:0]). The fast charge current setting at warm temperature (T3-T5) can be 100%, or 40% of fast charge current, ICHG (configured by JEITA_ISETH). The fast charge current setting at cool temperature (T1-T2) can be 100%, 40%, or 20% of fast charge current, ICHG, or charge suspend (configured by JEITA_ISETC[1:0]). Whenever the charger detects "warm" or "cool" temperature, termination is automatically disabled regardless of JEITA_VSET, JEITA_ISETH and JEITA_ISETC register bit settings.

Figure 21. TS Resistor Network

Assuming a 103AT NTC (Negative Temperature Coefficient) thermistor on the battery pack as shown above, the value of RT1 and RT2 can be determined by:

Equation 1.

Equation 2.

Select 0°C to 60°C range for Li-ion or Li-polymer battery:

R_NTC,T1 = 27.28kΩ

R_NTC,T5 = 3.02kΩ

RT1 = 5.24kΩ

RT2 = 30.31kΩ