Linear Technology LT3651-4.2 battery charger

Linear Technology has introduced the LT3651-4.2, a 4A monolithic synchronous buck battery charger for single-cell Li-Ion/polymer batteries.

It accepts inputs up to 32 V with a 40 V absolute maximum. Charge current is programmable and dynamically adjustable up to 4 A; fully integrated synchronous power devices minimise power dissipation and save board space.

User-selectable timer or C/10 termination requires no external microcontroller and simplifies the design. The device does not require external high-precision resistors to set the float voltage. Applications include industrial handheld instruments, 12 to 24 V motor vehicle and heavy equipment applications, desktop cradle chargers and notebook or tablet computers.

The programmable switching frequency (200 kHz to 1 MHz) enables the designer to balance solution size, power loss and filtering needs. Synchronous operation enables charging efficiencies to 90%. Final float voltage accuracy is ±0.5%, charge current accuracy is ±7.5% and C/10 detection accuracy is ±4%.

Once charging is ended, the device automatically enters a low current stand-by mode that reduces the input supply current to 80 µA. In shutdown, the input bias current is reduced to 15 µA.

It maximises battery life during all non-charging periods by draining <1 µA from the battery.

For safety and autonomous charge control, the device includes automatic restart and preconditioning, a thermistor input for temperature-qualified charging, programmable input current limit, bad battery detection and binary coded status output pins.