Li-ion/polymer chargers deliver up to 2A

Linear Technology Corporation has introduced the LT3650-4.1 and LT3650-4.2, compact, monolithic high-voltage battery chargers for single-cell Li-Ion/Polymer batteries. The device’s switchmode architecture minimizes power dissipation without compromising board space. The LT3650-4.1/4.2 operates from 4.75V to 32V and has a 40V absolute maximum rating for added system margin. User selectable timer or C/10 termination requires no external microcontroller and simplifies the design. Charge current is programmable and dynamically adjustable up to 2A; the power device is integrated on chip to save board space.

The LT3650-4.1/4.2 does not require external high-precision resistors to set the float voltage, further saving cost and space. Applications include industrial handheld instruments, 12V to 24V automotive and heavy equipment, desktop cradle chargers and small notebook or tablet computers. The LT3650-4.1 offers a 4.1V battery float voltage, allowing high temperature safety margin, while the LT3650-4.2 features a 4.2V final charge voltage for optimized battery run time.

The LT3650-4.1/4.2’s high operating frequency of 1MHz and current mode architecture allow the use of small inductors and capacitors, minimizing noise and filtering needs. Final float voltage accuracy is specified at 0.5%, charge current accuracy is 5% and C/10 detection accuracy is 2.5%. Once charging is terminated, the LT3650-4.1/4.2 automatically enters a low current standby mode that reduces the input supply current to 85uA. In shutdown, the input bias current is reduced to 15uA.

The LT3650-4.1/4.2 maximizes battery life during all non-charging periods, draining less than 1uA from the battery. For safety and autonomous charge control, the LT3650-4.1/4.2 includes features such as automatic restart and preconditioning, a thermistor input for temperature-qualified charging, programmable input current limit, bad battery detection and binary coded status output pins.

The LT3650-4.1 and LT3650-4.2 are housed in a compact, low-profile (0.75mm) 12-pin 3mm x 3mm DFN package, and are offered in both E and I grade versions, both operating from -40C to +85C. Pricing starts at $2.80 and $3.22, for the E & I grades respectively, in 1,000-piece quantities.