Battery Chargers Offer Constant Current Programmability

Configured to create a constant- or programmable-current/constant-voltage battery charger, the LT1513 and LT1513-2 500-kHz current-mode switching regulators provide constant-current and constant-voltage battery charging in flyback or SEPTIC (Single-Ended Primary Inductance Converter) topology, where the input voltage can vary above and below the battery voltage. The devices can charge single-cell as well as multi-cell batteries at voltages up to 25V for a 15V input. The 1513-2 IC can switch from a constant-current charge to a trickle charge, allowing a peak charge condition to be achieved in nickel-based batteries. Charging current is easily programmed with a dc voltage source or equivalent PWM signal. The device regulates at 0 mV at the IFB pin to provide a programmable current limit over a wide range. The LT1513 boasts a 1% accuracy in constant voltage mode and is suited for charging lead-acid or Li-ion battery systems.