LTC1731-8.2 LITEON [Lite-On Technology Corporation], LTC1731-8.2 Datasheet

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LTC1731-8.2

Manufacturer Part Number
LTC1731-8.2
Description
LITHIUM - LON LINEAR BATTERY CHARGER CONTROLLER
Manufacturer
LITEON [Lite-On Technology Corporation]
Datasheet
FEATURES
APPLICATIO S
TYPICAL APPLICATIO
, LTC and LT are registered trademarks of Linear Technology Corporation.
Complete Linear Charger Controller for
2-Cell Lithium-Ion Batteries
1% Voltage Accuracy
Programmable Charge Current
C/10 Charge Current Detection Output
Programmable Charge Termination Timer
Space Saving 8-Pin MSOP Package
Automatic Sleep Mode When Input Supply
is Removed (15 A Battery Drain)
Automatic Trickle Charging of Low Voltage Cells
Programmable for Constant-Current-Only Mode
Cellular Phones
Handheld Computers
Charging Docks and Cradles
Programmable Current Source
CHARGE
STATUS
C
TIMER
0.1 F
*SHUTDOWN INVOKED BY FLOATING THE PROG PIN
2k
U
2
3
CHRG
TIMER
LTC1731-8.4
400mA Li-Ion Charger
GND
V
CC
4
7
SENSE
PROG
DRV
BAT
U
8
6
1
5
R
19.6k
PROG
*
V
IN
= 9V
+
Q1
Si9430DY
R
0.2
SENSE
I
2-CELL
Li-ION
MBRM120T3
BAT
= 400mA
1731 TA01
1 F
10 F
DESCRIPTIO
The LTC
current/constant-voltage linear charger controllers for 2-
cell lithium-ion (Li-Ion)batteries. Nickel-cadmium (NiCd)
and nickel-metal-hydride (NiMH) batteries can also be
charged with constant current using external termina-
tion. The external sense resistor sets the charge current
with 7% accuracy. An internal resistor divider and preci-
sion reference set the final float potential with 1% accu-
racy. The output float voltages are set internally to 8.2V
(LTC1731-8.2) or 8.4V (LTC1731-8.4).
When the input supply is removed, the LTC1731-8.2/
LTC1731-8.4 automatically enter a low current sleep mode,
dropping the battery drain current to typically 15 A. An
internal comparator detects the end-of-charge (C/10) con-
dition while a programmable timer, using an external
capacitor, sets the total charge time. Fully discharged cells
are automatically trickle charged at 10% of the pro-
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-
ing, see the LTC1731-4.1 and LTC1731-4.2 data sheets.
Battery Charger Controller
®
400
300
200
100
1731-8.2/LTC1731-8.4 are complete constant-
LTC1731-8.2/LTC1731-8.4
0
0
CONSTANT
CURRENT
Typical Li-Ion Charge Cycle
0.5
U
1.0
TIME (HOURS)
Lithium-Ion Linear
CHARGE CURRENT
BATTERY VOLTAGE
CONSTANT
1.5
VOLTAGE
400mA HR BATTERY
LED OFF
CHRG
2.0
2.5
1731 TA01b
STOPS
TIMER
3.0
9
8
7
6
sn1731 17318fs
1

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LTC1731-8.2 Summary of contents

Page 1

... The output float voltages are set internally to 8.2V (LTC1731-8.2) or 8.4V (LTC1731-8.4). When the input supply is removed, the LTC1731-8.2/ LTC1731-8.4 automatically enter a low current sleep mode, dropping the battery drain current to typically internal comparator detects the end-of-charge (C/10) con- dition while a programmable timer, using an external capacitor, sets the total charge time ...

Page 2

... LTSW T LTPE JMAX The denotes the specifications which apply over the full operating = unless otherwise noted CONDITIONS Charger On, Current Mode Shutdown Mode Sleep Mode (Battery Drain Current) LTC1731-8.2 (9V V 12V) CC LTC1731-8.4 (9V V 12V 19.6k 0.2 PROG SENSE R = 19.6k 0.2 PROG ...

Page 3

... PROG R = 0.2 SENSE BAT (V) CC 1731 G01 LTC1731-8.2/LTC1731-8.4 The denotes the specifications which apply over the full operating = unless otherwise noted CONDITIONS (V – Falling CC BAT (V – Rising CC BAT – DIS ...

Page 4

... LTC1731-8.2/LTC1731-8 TYPICAL PERFOR A CE CHARACTERISTICS Trickle Charge Threshold Voltage vs Temperature 4. 4.93 4.92 4.91 4.90 –50 – 100 TEMPERATURE ( C) 1731 G03 Battery Charge Current 520 R = 19.6K PROG R = 0.2 SENSE BAT 510 500 490 480 (V) CC 1731 G09 4 Timer Accuracy vs V ...

Page 5

... CC and the IC will operate in constant-current mode only. Short the TIMER pin to GND to disable the internal timer and the C/10 functions. LTC1731-8.2/LTC1731-8.4 GND (Pin 4): Ground. PROG (Pin 5): Charge Current Program and Shutdown Input Pin. The charge current is programmed by connect- ing a resistor • ...

Page 6

... LTC1731-8.2/LTC1731-8.4 W BLOCK DIAGRA CHRG 2 C/10 100 A SHDN TIMER 3 OSCILLATOR C3 BATTERY CURRENT I = (2.457V • 800 )/(R BAT – STOP C/10 720 LOGIC SLP COUNTER V REF + + – – 2.5 A PROG 5 • PROG SENSE R PROG R SENSE 8 + 800 54mV – – – DRV BAT – ...

Page 7

... CC amplifier and the resistor divider provide regulation with 1% (max) accuracy. For NiMH and NiCd batteries, the LTC1731-8.2/LTC1731-8.4 can be turned into a current source by pulling the TIMER pin to V constant-current only mode, the voltage amplifier, timer and the trickle charge function are all disabled. ...

Page 8

... CHRG pin output is forced to a high impedance state. Shutdown The LTC1731-8.2/LTC1731-8.4 can be forced into shut- down by floating the PROG pin and allowing the internal 2.5 A current source to pull the pin above the 2.457V shutdown threshold voltage. The DRV pin is then pulled turning off the external P-channel MOSFET ...

Page 9

... A/mV. For every base current, a 1.6mV gain error shows up at the inputs of CA. With R 19.6k and 100mV across R 1.67% error in charge current. Constant-Current Only Mode The LTC1731-8.2/LTC1731-8.4 can be used as a pro- grammable current source by forcing the TIMER pin This is particularly useful for charging NiMH or NiCd CC batteries ...

Page 10

... LTC1731-8.2/LTC1731-8.4 PACKAGE DESCRIPTION 5.23 (.206) MIN 0.42 0.04 (.0165 .0015) TYP RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) GAUGE PLANE 0.18 (.077) NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006" ...

Page 11

... TYP 0.016 – 0.050 0.014 – 0.019 (0.355 – 0.483) TYP LTC1731-8.2/LTC1731-8.4 0.189 – 0.197* (4.801 – 5.004 0.150 – 0.157** (3.810 – 3.988) SO8 1298 0.004 – ...

Page 12

... LTC1731-8.2/LTC1731-8.4 U TYPICAL APPLICATIO CHARGE STATUS C TIMER 0.1 F RELATED PARTS PART NUMBER DESCRIPTION ® LT 1510-5 500kHz Constant-Voltage/Constant-Current Battery Charger LT1512 SEPIC Battery Charger LT1571-1/-2/-5 200kHz/500kHz 1.5A Constant-Current/Constant-Voltage Battery Charger LTC1615 SOT-23 Step-Up Switching Regulator LT1620 Rail-to-Rail Current Sense Amplifier LTC1682 Low Noise Doubler Charge Pump ...

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