LTC4001-1_15 Datasheet, PDF (1/20 Pages) Linear Technology – 2A Synchronous Buck Li-Ion Charger

FEATURES
n _{Low Power Dissipation}
n _{2A Maximum Charge Current}
n _{No External MOSFETs, Sense Resistor or}
Blocking Diode Required
n _{Remote Sensing at Battery Terminals}
n _{Programmable Charge Termination Timer}
n _{Preset 4.1V Float Voltage with ±0.5% Accuracy}
n _{4.1V Float Voltage Improves Battery Life and High}
Temperature Safety Margin
n _{Programmable Charge Current Detection/}
Termination
n _{Automatic Recharge}
n _{Thermistor Input for Temperature Qualified}
Charging
n _{Compatible with Current Limited Wall Adapters}
n _{Low Profile 16-Lead (4mm × 4mm) QFN Package}
APPLICATIONS
n _{Handheld Battery-Powered Devices}
n _{Handheld Computers}
n _{Charging Docks and Cradles}
n _{Digital Cameras}
n _{Smart Phones}
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
LTC4001-1
2A Synchronous
Buck Li-Ion Charger
DESCRIPTION
The LTC^®4001-1 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
LTC4001-1 includes complete charge termination circuitry,
automatic recharge and a ±1% 4.1V float voltage. Input
short-circuit protection is included so no blocking diode
is required.
This 4.1V version of the standard LTC4001 is intended
for applications which will be operated or stored above
approximately 60°C. Under these conditions, the reduced
float voltage will trade-off initial cell capacity for the benefit
of increased capacity retention over the life of the battery. A
reduced float voltage also minimizes swelling in prismatic
and polymer cells, and avoids open CID (pressure fuse)
in cylindrical cells.
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
LTC4001-1 is available in a low profile (0.75mm) 16-lead
(4mm × 4mm) QFN package.
TYPICAL APPLICATION
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
LTC4001-1
NTC
FAULT
EN
PROG IDET TIMER
SS GNDSENS
274Ω
0.22μF
0.1μF
10μF ^{+ 4.1V}
Li-Ion
40011 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
40011 TA01b
40011fa
1