The CN3722(Note 1) is a PWM switch-mode battery charger controller that can be powered by photovoltaic cell. The CN3722 is specially designed for charging 1 or multi-cell lithium ion batteries or LiFePO4 batteries with constant current and constant voltage mode. In constant voltage mode,the regulation voltage is set by the external resistor divider. The constant charging current is programmable with a single current sense resistor.