BATTERY VOLTAGE(V)
LTC1731-8.2/LTC1731-8.4
Lithium-Ion Linear
Battery Charger Controller
FEATURES
DESCRIPTIO
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Complete Linear Charger Controller for The LTC 1731-8.2/LTC1731-8.4 are complete constant-
2-Cell Lithium-Ion Batteries current/constant-voltage linear charger controllers for 2-
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1% Voltage Accuracy cell lithium-ion (Li-Ion)batteries. Nickel-cadmium (NiCd)
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Programmable Charge Current and nickel-metal-hydride (NiMH) batteries can also be
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C/10 Charge Current Detection Output charged with constant current using external termina-
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Programmable Charge Termination Timer tion. The external sense resistor sets the charge current
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Space Saving 8-Pin MSOP Package with 7% accuracy. An internal resistor divider and preci-
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Automatic Sleep Mode When Input Supply sion reference set the final float potential with 1% accu-
is Removed (15m A Battery Drain) racy. The output float voltages are set internally to 8.2V
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Automatic Trickle Charging of Low Voltage Cells (LTC1731-8.2) or 8.4V (LTC1731-8.4).
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Programmable for Constant-Current-Only Mode
When the input supply is removed, the LTC1731-8.2/
LTC1731-8.4 automatically enter a low current sleep mode,
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dropping the battery drain current to typically 15m A. An
APPLICATIO S
internal comparator detects the end-of-charge (C/10) con-
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Cellular Phones
dition while a programmable timer, using an external
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Handheld Computers
capacitor, sets the total charge time. Fully discharged cells
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Charging Docks and Cradles
are automatically trickle charged at 10% of the pro-
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Programmable Current Source
grammed current until battery voltage exceeds 4.95V.
The LTC1731-8.2/LTC1731-8.4 are available in the 8-pin
MSOP and SO packages. For 1-cell Li-Ion battery charg-
, LTC and LT are registered trademarks of Linear Technology Corporation. ing, see the LTC1731-4.1 and LTC1731-4.2 data sheets.
TYPICAL APPLICATIO
400mA Li-Ion Charger
Typical Li-Ion Charge Cycle
V = 9V
IN
9
CONSTANT CONSTANT
MBRM120T3 CURRENT VOLTAGE
7 BATTERY VOLTAGE
R
2k SENSE
V 1F
CC 400 8
0.2
8
400mA HR BATTERY
CHARGE
SENSE
STATUS
2
6
Q1
300
CHRG DRV
Si9430DY
CHARGE CURRENT
LTC1731-8.4
I = 400mA
BAT
3 1 200 7
TIMER BAT
CHRG
5
LED OFF
TIMER
PROG
100
C
TIMER STOPS
0.1F GND +
R * 2-CELL
PROG 10F
4
19.6k Li-ION
0 6
2.0 3.0
0 0.5 1.0 1.5 2.5
1731 TA01
TIME (HOURS)
*SHUTDOWN INVOKED BY FLOATING THE PROG PIN 1731 TA01b
sn1731 17318fs
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CHARGE CURRENT (mA)
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ULTC1731-8.2/LTC1731-8.4
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Input Supply Voltage (V ) ................................... 13.2V Operating Temperature Range (Note 2) .....40 to 85 C
CC
SENSE, DRV, BAT, TIMER, PROG ............ 0.3V to V Storage Temperature Range ................. 65 C to 150 C
CC
Lead Temperature (Soldering, 10 sec).................. 300 C
CHRG..................................................... 0.3V to 13.2V
PACKAGE/ORDER INFORMATION
ORDER PART ORDER PART
TOP VIEW
NUMBER NUMBER
TOP VIEW
BAT 1 8 SENSE
BAT 1 8 SENSE
LTC1731EMS8-8.2 LTC1731ES8-8.2
CHRG 2 7 V
CHRG 2 7 V CC
CC
TIMER 3 6 DRV
LTC1731EMS8-8.4 LTC1731ES8-8.4
TIMER 3 6 DRV
GND 4 5 PROG
GND PROG
4 5
MS8 PACKAGE
MS8 PART MARKING S8 PART MARKING
8-LEAD PLASTIC MSOP
S8 PACKAGE
T = 150 C, q = 200 C/W
8-LEAD PLASTIC SO
JMAX JA
LTSW 173182
T = 150 C, q = 125 C/W
JMAX JA
LTPE 173184
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T = 25 C. V = 9V unless otherwise noted.
A CC
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V Input Supply Voltage l 8.8 12 V
CC
I Input Supply Current Charger On, Current Mode l 13 mA
CC
Shutdown Mode l 12 mA
Sleep Mode (Battery Drain Current) 15 30 m A
V Regulated Output Voltage LTC1731-8.2 (9V V 12V) l 8.118 8.2 8.282 V
BAT CC
LTC1731-8.4 (9V V 12V) l 8.316 8.4 8.484 V
CC
I Current Mode Charge Current R = 19.6k, R = 0.2W 465 500 535 mA
BAT PROG SENSE
R = 19.6k, R = 0.2W l 415 500 585 mA
PROG SENSE
= 97.6k, R = 0.2W 70 100 130 mA
R
PROG SENSE
I Trickle Charge Current V = 4V, R = 19.6k, I = (V V )/0.2W l 30 50 100 mA
TRIKL BAT PROG TRIKL CC SENSE
V Trickle Charge Threshold Voltage BAT Rising l 4.7 4.95 5.1 V
TRIKL
V V Undervoltage Lockout Voltage V Rising l 8.2 8.8 V
UV CC CC
D V V Undervoltage Lockout Hysteresis V Falling 200 mV
UV CC CC
V Manual Shutdown Threshold Voltage PROG Pin Rising 2.457 V
MSD
PROG Pin Falling 2.446 V
I Drive Pin Current V = V 2V 26 m A
DRV DRV CC
sn1731 17318fs
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