LTC4080X

` Complete Linear Battery Charger with Integrated Buck Converter in 3mm x 3mm DFN Package Battery Charger:
` 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
` C/10 Charge Current Detection Output
` 5A Supply Current in Shutdown Mode Switching Regulator:
` High Effi ciency Synchronous Buck Converter
` 300mA Output Current (Constant-Frequency Mode)
` 2.7V to 4.5V Input Range (Powered from BAT Pin)
` 0.8V to V_BAT Output Range
` MODE Pin Selects Fixed (2.25MHz) Constant-Frequency PWM Mode or Low I<sub>CC</sub> (23A) Burst Mode<sup>®</sup> Operation
` 2A BAT Current in Shutdown Mode

V_CC, t < 1ms and Duty Cycle < 1% .............. 0.3V to 7V
V_CC Steady State ......................................... 0.3V to 6V
BAT,CHRG .................................................. 0.3V to 6V
EN CHRG, PROG, ACPR ................. 0.3V to V_CC + 0.3V
MODE, EN_BUCK .......................... 0.3V to V_BAT + 0.3V
FB ............................................................... 0.3V to 2V
BAT Short-Circuit Duration ............................Continuous
BAT Pin Current ...................................................800mA
PROG Pin Current ....................................................2mA
Junction Temperature .......................................... .125
Operating Temperature Range (Note 2) .. 40 to 85
Storage Temperature Range .................. 65 to 125
Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTC4080X is guaranteed to meet performance specifi cations from 0 to 85. Specifi cations over the 40 to 85 operating
temperature range are assured by design, characterization and correlation
with statistical process controls.

The LTC4080X is a complete constant-current/constantvoltage 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 it especially suitable for portable applications. Furthermore, the LTC4080X is specifi cally designed to work within USB power specifi cations.
 
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 LTC4080X battery charger also includes automatic recharge and soft-start to limit inrush current. If trickle charging is desired, please see the LTC4080 datasheet.

The LTC4080X 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 higheffi ciency Burst Mode operation that can be selected by the MODE pin.

The LTC4080X is available in 10-lead, low profi le (0.75 mm) 3mm × 3mm DFN and 10-lead MSE packages.