LTC4002
Standalone Li-Ion
Switch Mode Battery Charger
FEATURES
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DESCRIPTIO
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Wide Input Supply Range:
4.7V to 22V – 4.2 Version
8.9V to 22V – 8.4 Version
High Efficiency Current Mode PWM Controller with
500kHz Switching Frequency
±1%
Charge Voltage Accuracy
End-of-Charge Current Detection Output
3 Hour Charge Termination Timer
Constant Switching Frequency for Minimum Noise
±5%
Charge Current Accuracy
Low 10µA Reverse Battery Drain Current
Automatic Battery Recharge
Automatic Shutdown When Input Supply is Removed
Automatic Trickle Charging of Low Voltage Batteries
Battery Temperature Sensing and Charge
Qualification
Stable with Ceramic Output Capacitor
8-Lead SO and 10-Lead DFN Packages
The LTC
®
4002 is a complete battery charger controller for
one (4.2V) or two (8.4V) cell lithium-ion batteries. With a
500kHz switching frequency, the LTC4002 provides a
small, simple and efficient solution to fast charge Li-Ion
batteries from a wide range of supply voltages. An external
sense resistor sets the charge current with
±5%
accuracy.
An internal resistor divider and precision reference set the
final float voltage to 4.2V per cell with
±1%
accuracy.
When the input supply is removed, the LTC4002 automati-
cally enters a low current sleep mode, dropping the battery
drain current to 10µA. An internal comparator detects the
near end-of-charge condition while an internal timer sets
the total charge time and terminates the charge cycle. After
the charge cycle ends, if the battery voltage drops below
4.05V per cell, a new charge cycle will automatically begin.
The LTC4002 is available in the 8-lead SO and 10-lead DFN
packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
APPLICATIO S
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Portable Computers
Charging Docks
Handheld Instruments
TYPICAL APPLICATIO
1.5A Single Cell Li-Ion Battery Charger
V
IN
5V TO 22V
100
90
0.1µF
BAT
2k
V
CC
GATE
LTC4002ES8-4.2
10µF
EFFICIENCY (%)
80
CHARGE
STATUS
CHRG
SENSE
6.8µH
70
68mΩ
COMP
NTC
BAT
GND
22µF
10k
T
NTC
NTC: DALE NTHS-1206N02
60
5
10
15
INPUT VOLTAGE (V)
4002 TA02
0.47µF
2.2k
+
Li-Ion
BATTERY
4002 TA01
U
Efficiency vs Input Voltage
(CURVES INCLUDE
INPUT DIODE)
V
BAT
= 4V
V
BAT
= 3.8V
20
25
U
U
4002f
1
LINER [ LINEAR TECHNOLOGY ]
