Final Electrical Specifications
LTC1731-4.1
Lithium-Ion Linear
Battery Charger Controller
April 2000
FEATURES
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DESCRIPTION
The LTC
廬
1731-4.1 is a complete constant-current/con-
stant-voltage linear charge controller for lithium-ion bat-
teries. Nickel-cadmium (NiCd) and nickel-metal-hydride
(NiMH) batteries can also be charged with constant
current using external termination. The external sense
resistor sets the charge current with 5% accuracy. An
internal resistor divider and precision reference set the
final float potential with 1% accuracy. The output float
voltage is set internally to 4.1V.
When the input supply is removed, the LTC1731 automati-
cally enters a low current sleep mode, dropping the battery
drain current to 7碌A(chǔ) typically. An internal comparator
detects the end-of-charge (C/10) condition while a pro-
grammable timer, using an external capacitor, sets the
total charge time. Fully discharged cells are automatically
trickle charged at 10% of the programmed current until
cell voltage exceeds 2.457V.
The LTC1731-4.1 is available in the 8-pin MSOP and SO
packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
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Complete Linear Charger Controller for
1-Cell Lithium-Ion Batteries
1% Voltage Accuracy
Programmable Charge Current
C/10 Charge Current Detection Output
Programmable Charge Termination Timer
Space Saving, Thin 8-Pin MSOP Package
Automatic Sleep Mode When Input Supply
is Removed (7碌A(chǔ) Battery Drain)
Automatic Trickle Charging of Low Voltage Cells
Programmable for Constant-Current-Only Mode
APPLICATIONS
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Cellular Phones
Handheld Computers
Charging Docks and Cradles
Programmable Current Source
TYPICAL APPLICATION
500mA Li-Ion Charger
V
IN
5V TO 12V
MBRM120T3
7
1k
CHARGE
STATUS
V
CC
SENSE
2
CHRG
DRV
8
6
R
SENSE
0.2鈩?/div>
Q1
Si9430DY
I
BAT
= 500mA
LTC1731-4.1
3
C
TIMER
0.1碌F
TIMER
BAT
PROG
GND
4
1
5
R
PROG
*
19.6k
+
Li-ION
CELL
1731 TA01
*SHUTDOWN INVOKED BY FLOATING THE PROG PIN
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.
U
U
U
1碌F
10碌F
1
1
2
3
4
5
6
7
8
