LTC4121 Solar Panel Charging 4.2V Li-Ion Battery at 400mA

The LTC®4121 is a 400mA constant-current/constantvoltage (CC/CV) synchronous step-down battery charger. In addition to CC/CV operation, the LTC4121 regulates its input voltage to a programmable percentage of the input open-circuit voltage. This technique enables maximum power operation with high impedance input sources such as solar panels.