LTC4121/LTC4121-4.2 – 40V 400mA Synchronous Step-Down Battery Charger
- Wide Input Voltage Range: 4.4V to 40V
- Temperature Compensated Input Voltage Regulation for Maximum Power Point Tracking (MPPT)
- Adjustable Float Voltage 3.5V to 18V (LTC4121)
- Fixed 4.2V Float Voltage Option (LTC4121-4.2)
- High Efficiency: Up to 95%
- 50mA to 400mA Programmable Charge Current
- ±1% Feedback Voltage Accuracy
- Programmable 5% Accurate Charge Current
- Thermally Enhanced, Low Profile (0.75mm) 16-Lead (3mm × 3mm) QFN Package
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 maintains maximum power transfer with high impedance input sources such as solar panels.
An external resistor programs the charge current up to 400mA. The LTC4121-4.2 is suitable for charging Li-Ion/ Polymer batteries, while the programmable float voltage of the LTC4121 is suitable for several battery chemistries.