Final Electrical Specifications
LTC4052-4.2
Lithium-Ion Battery
Pulse Charger with
Overcurrent Protection
FEATURES
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DESCRIPTIO
July 2002
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Complete Standalone Pulse Charger for 1-Cell
Lithium-Ion Batteries
Requires No Microcontroller
Internal 0.35Ω NMOS Switch
Sense Resistor Limits Maximum Current for Safety
Programmable Charge Termination Timer for
Maximum Capacity Charging
No Blocking Diode Required
1% Float Voltage Accuracy
Near End-of-Charge (C/10) Detection Output
Low Battery Drain when Input Supply Is Removed
Automatic Trickle Charge for Low Battery
Automatic Battery Refresh
Thermal Shutdown Protection
Small 8-Pin Thermally Enhanced MSOP Package
The LTC
®
4052 is a complete standalone pulse charger
with integrated MOSFET for 1-cell lithium-ion batteries.
An external sense resistor provides maximum charge
current limiting as a safety precaution against a user
connecting a wall adapter with the incorrect or no current
limit. The internal MOSFET prevents reverse battery
current from flowing if the input voltage is shorted to
ground, eliminating the need for a blocking diode.
As the battery accepts charge and approaches the
programmed float voltage, the internal MOSFET begins
switching off and on with the duty cycle gradually decreas-
ing as the battery approaches a fully charged condition.
A programmable timer ends the charge cycle. The near
end-of-charge
C/10
condition is indicated at the CHRG pin
when the average charge current falls to one-tenth of the
wallpack current. Removing the input voltage puts the
LTC4052 into a sleep mode, dropping the battery current
drain to less than 1µA (maximum).
The LTC4052 is available in a tiny 8-pin thermally
enhanced MSOP package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
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Standalone Lithium-Ion Battery Charger
Personal Information Appliances
Cellular Telephones
Cradle Chargers
TYPICAL APPLICATIO
V
IN
= 4.5V TO 10V
WITH 1A
CURRENT LIMIT
Single Cell 4.2V, 1A, Standalone Li-Ion Battery Charger
4.5
4.7Ω
1k
1µF
1k
V
IN
LTC4052
GATE
CHRG
ACPR
SENSE
BAT
TIMER
GND
10k
0.047µF
R
SENSE
0.05Ω
BATTERY
VOLTAGE (V)
4.0
3.5
3.0
1.0
0.5
0
5
0
0
0.5
1.0
1.5
2.0
TIME (HOURS)
2.5
3.0
C/10
CONSTANT
CURRENT
PULSING
CURRENT
CHARGE
CYCLE
ENDS
AC PRESENT
0.022µF
1-CELL 4.2V
Li-Ion
BATTERY
C
TIMER
0.1µF
4052 TA01
CHRG (V)
CHARGE
CURRENT (A)
CHARGE STATUS
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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LTC4052 Charge Profile
4052 • TA01b
405242i
1
LINEAR [ LINEAR INTEGRATED SYSTEMS ]
