LTC4081 Datasheet | Linear Technology

Features Battery Charger: nn Constant-Current/Constant-Voltage Operation with Thermal Feedback to Maximize Charge Rate without Risk of Overheating nn Internal 4.5-Hour Safety Timer for Termination nn Charge Current Programmable Up to 500m A with 5% Accuracy nn NTC Thermistor Input for Temperature Qualified Charging nn C/10 Charge Current Detection Output nn 5µA Supply Current in Shutdown Mode Switching Regulator: nn High Efficiency Synchronous Buck Converter nn 300m A Output Current (Constant-Frequency Mode) nn 2.7V to 4.5V Input Range (Powered from BAT Pin) nn 0.8V to VBAT Output Range nn MODE Pin Selects Fixed (2.25MHz) Constant-Frequency PWM Mode or Low ICC (23µA) Burst Mode® Operation nn 2µA BAT Current in Shutdown Mode nn 10-Lead, Low Profile (0.75 mm) 3mm × 3mm DFN Package APPLICATIONS nn Wireless Headsets nn Bluetooth Applications nn Portable MP3 Players nn Multifunction Wristwatches 500m A Li-Ion Charger with NTC Input and 300m A Synchronous Buck DESCRIPTION The LTC®4081 is a plete constant-current/constantvoltage linear battery charger for a single-cell 4.2V lithium-ion/polymer battery with an integrated 300m A synchronous buck converter. A 3mm × 3mm DFN package and low external ponent count make the LTC4081 especially suitable for portable applications. Furthermore, the LTC4081 is specifically designed to work within USB power specifications. The CHRG pin indicates when charge current has dropped to ten percent of its programmed value (C/10). An internal 4.5-hour timer terminates the charge cycle. The fullfeatured LTC4081 battery charger also includes trickle charge, automatic recharge, soft-start (to limit inrush current) and an NTC thermistor input used to monitor battery temperature. The LTC4081 integrates a synchronous buck converter that is powered from the BAT pin. It has an adjustable output voltage and can deliver up to 300m A of load current. The buck converter also Features low current high efficiency Burst Mode operation that can be...