LTC4001 Datasheet, PDF (1/20 Pages) Linear Technology – 2A Synchronous Buck Li-Ion Charger

LTC4001
2A Synchronous
Buck Li-Ion Charger
FEATURES
■ _{Low Power Dissipation}
■ _{2A Maximum Charge Current}
■ _{No External MOSFETs, Sense Resistor or Blocking}
Diode Required
■ _{Remote Sensing at Battery Terminals}
■ _{Programmable Charge Termination Timer}
■ _{Preset 4.2V Float Voltage with ±0.5% Accuracy}
■ _{Programmable Charge Current Detection/Termination}
■ _{Automatic Recharge}
■ _{Thermistor Input for Temperature Qualified Charging}
■ _{Compatible with Current Limited Wall Adapters}
■ _{Low Profile 16-Lead (4mm × 4mm) QFN Package}
U
APPLICATIO S
■ _{Handheld Battery-Powered Devices}
■ _{Handheld Computers}
■ _{Charging Docks and Cradles}
■ _{Digital Cameras}
■ _{Smart Phones}
DESCRIPTIO
The LTC^®4001 is a 2A Li-Ion battery charger intended for
5V wall adapters. It utilizes a 1.5MHz synchronous buck
converter topology to reduce power dissipation during
charging. Low power dissipation, an internal MOSFET and
sense resistor allow a physically small charger that can be
embedded in a wide range of handheld applications. The
LTC4001 includes complete charge termination circuitry,
automatic recharge and a ±1% 4.2V float voltage. Input
short-circuit protection is included so no blocking diode is
required.
Battery charge current, charge timeout and end-of-charge
indication parameters are set with external components.
Additional features include shorted cell detection, tempera-
ture qualified charging and overvoltage protection. The
LTC4001 is available in a low profile (0.75mm) 16-lead
(4mm × 4mm) QFN package.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATIO
2A Single Cell Li-Ion Battery Charger
1.5µH
V_IN
4.5V TO 5.5V
10µF
SW
V_INSENSE
PV_IN
SENSE
BATSENS
BAT
PGND
CHRG
LTC4001
NTC
FAULT
EN
PROG IDET TIMER
SS GNDSENS
274Ω
0.22µF
0.1µF
+
10µF
4.2V
Li-Ion
4001 TA01a
Power Loss vs V_BAT
Charging (PWM Mode)
1.25
1.00
0.75
0.50
0.25
V_IN = 5V
2A CHARGER
0
3
3.25 3.5 3.75
V_BAT (V)
4
4.25
4001 TA01b
4001f
1