Linear Technology's LTC3128 is a high efficiency, input current-limited buck-boost supercapacitor charger with active charge balancing for 1 or 2 series supercapacitors. The LTC3128 features an average input current limit that can be programmed up to 3A with +/-2% accuracy, preventing power source overload while minimizing capacitor recharge time. Its active charge balancing eliminates dissipative external ballast resistors, ensuring balanced operation and charging with mismatched capacitors, and less frequent recharge cycles, Linear said. A programmable maximum capacitor voltage clamp actively monitors and enforces the voltage across each capacitor in the series stack, ensuring reliable operation as capacitors age and develop mismatched capacities. The low noise buck-boost topology allows the output supercapacitor to be charged whether above or below the input. The low-RDS(on), low gate charge synchronous switches provide high efficiency conversion to minimize the charging time of storage elements. The LTC3128's input current limit and maximum capacitor voltage are each programmed using a single resistor. Average input current is controlled over a 0.5A to 3A programming range, and the individual maximum capacitor voltage can be set from 1.6V to 3.0V. The LTC3128 is housed in 4mm x 5mm QFN and 24-lead TSSOP packages, both featuring operation from -40?C to 125?C.