Supercapacitor charger features bi-directional operation for fast charging and back-up

New from Linear Technology, the LTC3110 is a bi-directional, programmable input current buck-boost supercapacitor charger with active charge balancing for 1- or 2-series supercapacitors. The proprietary low-noise buck-boost topology does the work of two separate switching regulators, saving size, cost and complexity. The LTC3110 operates in two modes, backup and charge mode. In backup mode, the device maintains a system voltage, VSYS, of 1.71V to 5.25V, powered from the supercapacitor stored energy. Further, the supercapacitor storage input, VCAP, features a wide practical operating range from 5.5V down to 0.1V. This ensures that all practical stored supercapacitor energy is utilized, thereby extending backup times or shrinking the storage capacitors. Alternatively, in charge mode when the main power system is active, the LTC3110 can autonomously or through user command reverse the direction of power flow using the regulated system voltage to charge and balance the supercapacitors. VCAP is efficiently charged to above or below VSYS by the buck-boost PWM (pulse width modulator). The device also features a charge-mode average input current limit that can be programmed up to 2A with +/-2% accuracy, preventing system power source overload while minimizing capacitor recharge time, says the company.