Lithium Battery Charging Integrated Circuit Diagram

Lithium battery charging integrated circuit diagram (I)

The figure shows a lithium battery charging integrated circuit. In the figure, IClMAX1811 is a lithium battery charging control circuit. When K is connected, the charging voltage is 4.2V. When K is disconnected, the charging voltage is 4.1V.

Lithium battery charging integrated circuit diagram (II)

The typical protection circuit of a 4-cell battery pack using UCC3957 is shown in the figure:

In the figure, VR1 and R2 are used to protect the charging FET transistor VT1 when the charger open circuit charging voltage is too high. In this application circuit, the discharge FET transistor VT2 is turned off during a short circuit. Due to the distributed inductance of the battery pack output, a negative voltage mutation will occur at this time; this negative mutation will exceed the withstand voltage of the discharge FET transistor VT2, and this negative mutation will also damage the UCC3597. VD1 in the figure clamps this negative mutation to protect the discharge FET transistor VT2, and C5 should be placed directly at the top and bottom of the battery pack.

Because when the discharge overcurrent protection is in effect, the negative voltage overcharge generated by the discharge FET transistor VT2 is related to the size of the discharge current, and is related to the rise and fall time of the on and off drive pulse of the discharge FET transistor VT2. Therefore, R3, C5, and R4 are used in the figure to control the size.