LINEAR Technology, represented in Australia by Soanar , has released the LTC4002-8.4, a standalone switch-mode battery charger controller that can charge a two-cell 8.4V Li-Ion battery at a high rate without compromising board space for heat dissipation.
It includes automatic shutdown, battery preconditioning, battery temperature sensing, an end-of-charge indicator and a three-hour charge termination timer. The charger is offered in a 3mm x 3mm DFN and an eight-lead SO. The total size is 2cm x 2cm. Applications include handheld medical devices, industrial and communication test equipment, charging docks, tablet PCs and battery backup systems.
The LTC4002-8.4 is a current mode PWM controller with 500kHz switching frequency. It drives an external P-channel MOSFET for delivering charge currents as high as 4A with efficiencies up to 90%. The output voltage is set for the final float voltage of 8.4V with ±1% accuracy and charge accuracy of ±5%. The device operates from a selection of wall adapters from 9V to 22V.
The system’s operating frequency and current mode architecture allow the use of small inductors and capacitors. The IC's constant switching frequency minimises noise and filtering needs. The battery charger is stable with all types of output capacitors including low-ESR ceramic capacitors. An internal comparator detects the end-of-charge current and an integrated timer sets the total charge time and terminates the charge cycle after three hours. The LTC4002-8.4 automatically enters sleep mode, dropping the battery drain current to 10uA.