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 4.1 V charge termination is disabled for cool and warm conditions.

The charger provides flexible voltage/current settings beyond the JEITA requirement. The voltage setting at warm temperature (T3-T5) can be VREG or 4.1V (configured by JEITA_VSET). The current setting at cool temperature (T1-T2) can be further reduced to 20% of fast charge current (JEITA_ISET).

Figure 9-3 JEITA Profile: Charging Current

Figure 9-4 JEITA Profile: Charging Voltage

Figure 9-5 TS Resistor Network

Equation 1 through Equation 2 describe updates to the resistor bias network.

Equation 1.

Equation 2.

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

• RTH_COLD = 27.28 KΩ
• RTH_HOT = 3.02 KΩ
• RT1 = 5.23 KΩ
• RT2 = 30.9 KΩ