LTC4081 - 500mA Li-Ion Charger with NTC Input and 300mA Synchronous Buck

The LTC4081 is a complete constant-current / constant voltage linear battery charger for a single-cell 4.2V lithium-ion/polymer battery with an integrated 300mA synchronous buck converter. A 3mm × 3mm DFN package and low external component 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 full-featured 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 300mA of load current. The buck converter also features low-current high efficiency Burst Mode operation that can be selected by the MODE pin.

The LTC4081 is available in a 10-lead, low profile (0.75 mm) 3mm × 3mm DFN package.

Features

Constant-Current/Constant-Voltage Operation with Thermal Feedback to Maximize Charge Rate Without Risk of Overheating
Internal 4.5 Hour Safety Timer for Termination
Charge Current Programmable Up to 500mA with 5% Accuracy
NTC Thermistor Input for Temperature Qualified Charging
C/10 Charge Current Detection Output
5µA Supply Current in Shutdown Mode Switching
High Efficiency Synchronous Buck Converter
300mA Output Current (Constant-Frequency Mode)
2.7V to 4.5V Input Range (Powered from BAT Pin)
0.8V to VBAT Output Range
MODE Pin Selects Fixed (2.25MHz) Constant-Frequency PWM Mode or Low ICC (23µA) Burst Mode Operation
2µA BAT Current in Shutdown Mode
10-lead, low profile (0.75 mm) 3mm × 3mm DFN package