LTC1732-8.4
Lithium-Ion Linear
Battery Charger Controller
FEATURES
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DESCRIPTIO
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Complete Linear Charger Controller for 2-Cell
Lithium-Ion Batteries
Preset Charge Voltage with
±1%
Accuracy
Programmable Charge Current
C/10 Charge Current Detection Output
Programmable Charge Termination Timer
Small, Thin 10-Pin MSOP Package
Input Supply (Wall Adapter) Detection Output
8.8V to 12V Input Voltage Range
Automatic Sleep Mode When Input Supply
Is Removed (Only 10µA Battery Drain)
Automatic Trickle Charging of Low Voltage Cells
Programmable for Constant-Current-Only Mode
Battery Insertion Detect and Automatic Charging
of Low-Battery
Automatic Battery Recharge
The LTC
®
1732-8.4 is a complete constant-current/con-
stant-voltage linear charge controller for lithium-ion
(Li-Ion) batteries. Nickel-cadmium (NiCd) and nickel metal-
hydride (NiMH) batteries can also be charged with con-
stant current using external termination. Charge current
can be programmed with
±7%
accuracy using external
sense and program resistors. An internal resistor divider
and precision reference set the final float voltage with
±1%
accuracy.
When the input supply is removed, the LTC1732-8.4
automatically enters a low current sleep mode, dropping
the battery drain current to 10µA. 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
battery voltage exceeds 4.9V.
The LTC1732-8.4 begins a new charge cycle when a
discharged battery is connected to the charger or when the
input power is applied. In additon, if the battery remains
connected to the charger and the cell voltage drops below
8.05V, a new charge cycle will begin.
The LTC1732-8.4 is available in the 10-pin MSOP package.
APPLICATIO S
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Cellular Phones
Handheld Computers
Charging Docks and Cradles
Digital Cameras and Camcorders
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
400mA 2-Cell 8.4V Li-Ion Battery Charger
V
IN
= 10V
MBRM120T3
R
SENSE
0.25Ω
Q1
Si9430DY
I
BAT
= 400mA
Typical Li-Ion Charge Cycle
CONSTANT
CURRENT
CONSTANT
VOLTAGE
BATTERY VOLTAGE
400
300
CHARGE CURRENT
200
100
0
CHRG
LED OFF
7
TIMER
STOPS
6
3.0
400mA HR BATTERY
8
9
CHARGE CURRENT (mA)
R1
1k
R2
1k
3
2
SEL
8
V
CC
SENSE
DRV
9
7
1µF
CHRG
LTC1732-8.4
10
4
C
TIMER
0.1µF
ACPR
TIMER
BAT
PROG
1
6
R
PROG
*
19.6k
GND
5
10µF
+
8.4V
Li-Ion
BATTERY
0
0.5
*SHUTDOWN INVOKED BY FLOATING THE PROG PIN
1732-8.4 TA01
U
BATTERY VOLTAGE(V)
2.0
1.5
1.0
TIME (HOURS)
2.5
1732-8.4 TA01b
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17328f
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LTC1732-8.4
ABSOLUTE
MAXIMUM
RATINGS
(Note 1)
PACKAGE/ORDER INFORMATION
TOP VIEW
BAT
SEL
CHRG
TIMER
GND
1
2
3
4
5
10
9
8
7
6
ACPR
SENSE
V
CC
DRV
PROG
Input Supply Voltage (V
CC
) ................................... 13.2V
SENSE, DRV, BAT, SEL,
TIMER, PROG, CHRG, ACPR ................. – 0.3V to 13.2V
Operating Temperature Range (Note 2) .... – 40° to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
LTC1732EMS-8.4
MS10 PART MARKING
LTWW
MS10 PACKAGE
10-LEAD PLASTIC MSOP
T
JMAX
= 140°C,
θ
JA
= 180°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 9V unless otherwise noted.
SYMBOL
V
CC
I
CC
PARAMETER
Input Supply Voltage
Input Supply Current
Charger On, Current Mode
Shutdown Mode
Sleep Mode (Battery Drain Current)
9V
≤
V
CC
≤
12V, V
SEL
= V
CC
R
PROG
= 19.6k, R
SENSE
= 0.2Ω
R
PROG
= 19.6k, R
SENSE
= 0.2Ω
R
PROG
= 97.6k, R
SENSE
= 0.2Ω
I
TRIKL
V
TRIKL
V
UV
∆V
UV
V
MSD
V
ASD
V
DIS
I
PROG
V
PROG
V
ACPR
I
CHRG
V
CHRG
I
DRV
Trickle Charge Current
Trickle Charge Threshold Voltage
V
CC
Undervoltage Lockout Voltage
V
CC
Undervoltage Lockout Hysteresis
Manual Shutdown Threshold Voltage
Automatic Shutdown Threshold Voltage
Voltage Mode Disable Threshold Voltage
PROG Pin Current
PROG Pin Voltage
ACPR Pin Output Low Voltage
CHRG Pin Weak Pull-Down Current
CHRG Pin Output Low Voltage
Drive Pin Current
PROG Pin Low to High
PROG Pin High to Low
(V
CC
– V
BAT
) High to Low
(V
CC
– V
BAT
) Low to High
V
DIS
= V
CC
– V
TIMER
Internal Pull-Up Current, No R
PROG
PROG Pin Source Current,
∆V
PROG
≤
5mV
R
PROG
=19.6k
I
ACPR
= 5mA
V
CHRG
= 1V
I
CHRG
= 5mA
V
DRV
= V
CC
– 2V
15
2.5
q
ELECTRICAL CHARACTERISTICS
CONDITIONS
q
q
q
q
q
MIN
8.8
TYP
1
1
10
MAX
12
3
3
30
8.484
535
585
140
125
5.1
8.7
UNITS
V
mA
mA
µA
V
mA
mA
mA
mA
V
V
mV
V
V
V
BAT
I
BAT
Regulated Output Float Voltage
Current Mode Charge Current
8.316
465
415
60
30
4.7
8.4
500
100
50
4.9
8.2
400
2.457
2.446
V
BAT
= 4V, R
PROG
= 19.6k, I
TRIKL
= (V
CC
– V
SENSE
)/0.2Ω
q
From Low to High
From Low to High
q
q
30
40
54
69
90
100
0.4
300
2.457
0.6
35
0.6
26
1.2
55
1.2
2
U
W
U
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W W
W
mV
mV
V
µA
µA
V
V
µA
V
µA
17328f
LTC1732-8.4
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 9V unless otherwise noted.
SYMBOL
I
C/10
t
TIMER
V
RECHRG
PARAMETER
10% Charge Current Indication Level
TIMER Accuracy
Recharge Threshold Voltage
CONDITIONS
R
PROG
= 19.6k, R
SENSE
= 0.2Ω
C
TIMER
= 0.1µF
V
BAT
from High to Low
7.85
q
ELECTRICAL CHARACTERISTICS
MIN
25
TYP
50
10
8.05
MAX
100
UNITS
mA
%
V
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
The LTC1732EMS-8.4 is guaranteed to meet performance
specifications from 0°C to 70°C. Specifications over the –40°C to 85°C
operating temperature range are assured by design, characterization and
correlation with statistical process controls.
TYPICAL PERFOR A CE CHARACTERISTICS
Trickle Charge Current vs V
CC
60
60
55
R
PROG
= 19.6K
R
SENSE
= 0.2Ω
V
BAT
= 4V
T
A
= 25°
I
TRKL
(mA)
I
TRKL
(mA)
50
50
V
TRKL
(V)
45
40
9
10
V
CC
(V)
11
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1732-8.4 G01
Trickle Charge Current vs
Temperature
R
PROG
= 19.6K
R
SENSE
= 0.2Ω
V
BAT
= 4V
V
CC
= 9V
Trickle Charge Threshold Voltage
vs V
CC
4.96
4.95
4.94
4.93
4.92
4.91
R
PROG
= 19.6K
T
A
= 25°
55
45
4.90
4.89
12
40
–50 –25
0
25
50
75
100
125
4.88
9
10
V
CC
(V)
11
12
1732-8.4 G03
TEMPERATURE (°C)
1732-8.4 G02
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LTC1732-8.4
TYPICAL PERFOR A CE CHARACTERISTICS
Trickle Charge Threshold Voltage
vs Temperature
4.94
V
CC
= 9V
4.93
t
TIMER
(%)
t
TIMER
(%)
V
TRKL
(V)
4.92
4.91
4.90
–50 –25
0
25
50
75
TEMPERATURE (°C)
1732-8.4 G04
Battery Charge Current vs V
CC
520
540
510
I
BAT
(mA)
R
PROG
= 19.6K
R
SENSE
= 0.2Ω
V
BAT
= 6V
T
A
= 25°
I
BAT
(mA)
500
500
490
V
PROG
(V)
490
480
9
10
V
CC
(V)
11
Program Pin Voltage vs
Temperature
2.470
R
PROG
= 19.6k
V
CC
= 9V
2.465
V
RECHRG
(V)
V
PROG
(V)
2.460
2.455
2.450
–50 –25
0
TEMPERATURE (°C)
1732-8.4 G10
4
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100
25
Timer Accuracy vs V
CC
110
110
Timer Accuracy vs Temperature
C
TIMER
= 0.1µF
V
CC
= 9V
105
C
TIMER
= 0.1µF
V
BAT
= 6V
T
A
= 25°
105
100
100
95
95
125
90
9
10
V
CC
(V)
11
12
1732-8.4 G05
90
–50 –25
0
25
50
75
100
125
TEMPERATURE (°C)
1732-8.4 G06
Battery Charge Current vs
Temperature
530
520
510
R
PROG
= 19.6K
R
SENSE
= 0.2Ω
V
BAT
= 6V
V
CC
= 9V
Program Pin Voltage vs V
CC
2.48
R
PROG
= 19.6K
V
BAT
= 6V
T
A
= 25°
2.47
2.46
480
470
460
–50 –25
0
25
50
75
100
125
2.45
12
1732-8.4 G07
2.44
9
10
V
CC
(V)
11
12
1732-8.4 G09
TEMPERATURE (°C)
1732-8.4 G08
Recharge Threshold Voltage vs
Temperature
8.25
V
CC
= 9V
8.15
8.05
7.95
50
75
100
125
7.85
–50 –25
0
25
50
75
100
125
TEMPERATURE (°C)
1732-8.4 G11
17328f
LTC1732-8.4
PIN FUNCTIONS
BAT (Pin 1):
Battery Sense Input. A bypass capacitor of
10µF or more is required to keep the loop stable when the
battery is not connected. A precision internal resistor
divider sets the final float voltage. The resistor divider is
disconnected in sleep mode to reduce the current drain on
the battery.
SEL (Pin 2):
This pin must be connected to V
CC
.
CHRG (Pin 3):
Open-Drain Charge Status Output. When
the battery is charging, the CHRG pin is pulled low by an
internal N-channel MOSFET. When the charge current
drops to 10% of the full-scale current for more than 15ms,
the N-channel MOSFET turns off and a 35µA current
source is connected from the CHRG pin to GND. When the
timer runs out or the input supply is removed, the current
source is disconnected and the CHRG pin is forced into a
high impedance state.
TIMER (Pin 4):
Timer Capacitor and Constant-Voltage
Mode Disable Input Pin. The timer period is set by placing
a capacitor, C
TIMER
, to GND. The timer period is t
TIMER
=
(C
TIMER
• 3 hours)/(0.1µF). When the TIMER pin is
connected to V
CC
, the timer is disabled, thus the constant-
voltage mode is turned off and the IC will operate in
constant-current mode only. Shorting the TIMER pin to
GND will disable the internal timer function and the
C/10
function.
GND (Pin 5):
Ground.
PROG (Pin 6):
Charge Current Program and Shutdown
Input Pin. The charge current is programmed by connect-
ing a resistor, R
PROG
to ground. The charge current is I
BAT
= (V
PROG
• 800Ω)/(R
PROG
• R
SENSE
). The IC can be forced
into shutdown by floating the PROG pin and allowing the
internal 2.5µA current source to pull the pin above the
2.457V shutdown threshold voltage.
DRV (Pin 7):
Drive Output Pin for the P-Channel MOSFET
or PNP Transistor. If a PNP transistor is used, it must have
high gain (see Applications Information section).
V
CC
(Pin 8):
Input Supply Voltage. V
CC
can range from
8.8V to 12V. If V
CC
drops below V
BAT
+ 54mV, for example
when the input supply is disconnected, then the IC enters
sleep mode with I
CC
< 30µA. Bypass this pin with a 1µF
capacitor.
SENSE (Pin 9):
Current Sense Input. A sense resistor,
R
SENSE
, must be connected from V
CC
to the SENSE pin.
This resistor is chosen using the following equation:
R
SENSE
= (V
PROG
• 800Ω)/(R
PROG
• I
BAT
)
ACPR (Pin 10):
Wall Adapter Present Output. When the
input voltage (wall adapter) is applied to the LTC1732-8.4,
this pin is pulled to ground by an internal N-channel
MOSFET which is capable of sinking 5mA to drive an
external LED (See Applications Information Section).
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