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LTC1732-8.4
17328f
TYPICAL APPLICATIO
U
FEATURES
APPLICATIO S
U
DESCRIPTIO
U
Lithium-Ion Linear
Battery Charger Controller
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 10
A. 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.
s
Complete Linear Charger Controller for 2-Cell
Lithium-Ion Batteries
s
Preset Charge Voltage with
1% Accuracy
s
Programmable Charge Current
s
C/10 Charge Current Detection Output
s
Programmable Charge Termination Timer
s
Small, Thin 10-Pin MSOP Package
s
Input Supply (Wall Adapter) Detection Output
s
8.8V to 12V Input Voltage Range
s
Automatic Sleep Mode When Input Supply
Is Removed (Only 10
A Battery Drain)
s
Automatic Trickle Charging of Low Voltage Cells
s
Programmable for Constant-Current-Only Mode
s
Battery Insertion Detect and Automatic Charging
of Low-Battery
s
Automatic Battery Recharge
s
Cellular Phones
s
Handheld Computers
s
Charging Docks and Cradles
s
Digital Cameras and Camcorders
, LTC and LT are registered trademarks of Linear Technology Corporation.
400mA 2-Cell 8.4V Li-Ion Battery Charger
V
IN
= 10V
SENSE
DRV
R2
1k
R
SENSE
0.25
R
PROG
*
19.6k
8.4V
Li-Ion
BATTERY
LTC1732-8.4
*SHUTDOWN INVOKED BY FLOATING THE PROG PIN
BAT
CHRG
9
8
2
MBRM120T3
10
F
1732-8.4 TA01
1
F
I
BAT
= 400mA
C
TIMER
0.1
F
Q1
Si9430DY
7
1
6
5
+
3
10
4
ACPR
TIMER
PROG
GND
SEL
V
CC
R1
1k
TIME (HOURS)
0
CHARGE CURRENT (mA)
400
300
200
100
0
9
8
7
6
1.5
2.5
1732-8.4 TA01b
0.5
1.0
2.0
3.0
CONSTANT
VOLTAGE
CONSTANT
CURRENT
TIMER
STOPS
CHRG
LED OFF
BATTERY VOLTAGE
400mA HR BATTERY
CHARGE CURRENT
BATTERY VOLTAGE(V)
Typical Li-Ion Charge Cycle
2
LTC1732-8.4
17328f
ORDER PART
NUMBER
(Note 1)
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
LTC1732EMS-8.4
T
JMAX
= 140
C,
JA
= 180
C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ABSOLUTE
M
AXI
M
U
M
RATINGS
W
W
W
U
PACKAGE/ORDER I
N
FOR
M
ATIO
N
W
U
U
MS10 PART MARKING
LTWW
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.
ELECTRICAL CHARACTERISTICS
1
2
3
4
5
BAT
SEL
CHRG
TIMER
GND
10
9
8
7
6
ACPR
SENSE
V
CC
DRV
PROG
TOP VIEW
MS10 PACKAGE
10-LEAD PLASTIC MSOP
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
CC
Input Supply Voltage
q
8.8
12
V
I
CC
Input Supply Current
Charger On, Current Mode
q
1
3
mA
Shutdown Mode
q
1
3
mA
Sleep Mode (Battery Drain Current)
10
30
A
V
BAT
Regulated Output Float Voltage
9V
V
CC
12V, V
SEL
= V
CC
q
8.316
8.4
8.484
V
I
BAT
Current Mode Charge Current
R
PROG
= 19.6k, R
SENSE
= 0.2
465
500
535
mA
R
PROG
= 19.6k, R
SENSE
= 0.2
q
415
585
mA
R
PROG
= 97.6k, R
SENSE
= 0.2
60
100
140
mA
I
TRIKL
Trickle Charge Current
V
BAT
= 4V, R
PROG
= 19.6k, I
TRIKL
= (V
CC
V
SENSE
)/0.2
q
30
50
125
mA
V
TRIKL
Trickle Charge Threshold Voltage
From Low to High
q
4.7
4.9
5.1
V
V
UV
V
CC
Undervoltage Lockout Voltage
From Low to High
q
8.2
8.7
V
V
UV
V
CC
Undervoltage Lockout Hysteresis
400
mV
V
MSD
Manual Shutdown Threshold Voltage
PROG Pin Low to High
2.457
V
PROG Pin High to Low
2.446
V
V
ASD
Automatic Shutdown Threshold Voltage
(V
CC
V
BAT
) High to Low
30
54
90
mV
(V
CC
V
BAT
) Low to High
40
69
100
mV
V
DIS
Voltage Mode Disable Threshold Voltage
V
DIS
= V
CC
V
TIMER
0.4
V
I
PROG
PROG Pin Current
Internal Pull-Up Current, No R
PROG
2.5
A
PROG Pin Source Current,
V
PROG
5mV
q
300
A
V
PROG
PROG Pin Voltage
R
PROG
=19.6k
2.457
V
V
ACPR
ACPR Pin Output Low Voltage
I
ACPR
= 5mA
0.6
1.2
V
I
CHRG
CHRG Pin Weak Pull-Down Current
V
CHRG
= 1V
15
35
55
A
V
CHRG
CHRG Pin Output Low Voltage
I
CHRG
= 5mA
0.6
1.2
V
I
DRV
Drive Pin Current
V
DRV
= V
CC
2V
26
A
3
LTC1732-8.4
17328f
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
I
C/10
10% Charge Current Indication Level
R
PROG
= 19.6k, R
SENSE
= 0.2
q
25
50
100
mA
t
TIMER
TIMER Accuracy
C
TIMER
= 0.1
F
10
%
V
RECHRG
Recharge Threshold Voltage
V
BAT
from High to Low
7.85
8.05
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.
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.
ELECTRICAL CHARACTERISTICS
V
CC
(V)
9
I
TRKL
(mA)
10
11
12
1732-8.4 G01
60
55
50
45
40
R
PROG
= 19.6K
R
SENSE
= 0.2
V
BAT
= 4V
T
A
= 25
I
TRKL
(mA)
60
55
50
45
40
TEMPERATURE (
C)
50
100
1732-8.4 G02
0
50
25
25
75
125
R
PROG
= 19.6K
R
SENSE
= 0.2
V
BAT
= 4V
V
CC
= 9V
V
CC
(V)
9
V
TRKL
(V)
10
11
12
1732-8.4 G03
4.96
4.95
4.94
4.93
4.92
4.91
4.90
4.89
4.88
R
PROG
= 19.6K
T
A
= 25
Trickle Charge Current vs V
CC
Trickle Charge Current vs
Temperature
Trickle Charge Threshold Voltage
vs V
CC
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
4
LTC1732-8.4
17328f
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
TEMPERATURE (
C)
50
V
TRKL
(V)
100
1732-8.4 G04
0
50
4.94
4.93
4.92
4.91
4.90
25
25
75
125
V
CC
= 9V
V
CC
(V)
9
t
TIMER
(%)
10
11
12
1732-8.4 G05
110
105
100
95
90
C
TIMER
= 0.1
F
V
BAT
= 6V
T
A
= 25
TEMPERATURE (
C)
50
t
TIMER
(%)
100
1732-8.4 G06
0
50
110
105
100
95
90
25
25
75
125
C
TIMER
= 0.1
F
V
CC
= 9V
Trickle Charge Threshold Voltage
vs Temperature
Timer Accuracy vs V
CC
Timer Accuracy vs Temperature
V
CC
(V)
9
I
BAT
(mA)
10
11
12
1732-8.4 G07
520
510
500
490
480
R
PROG
= 19.6K
R
SENSE
= 0.2
V
BAT
= 6V
T
A
= 25
I
BAT
(mA)
540
530
520
510
500
490
480
470
460
TEMPERATURE (
C)
50
100
1732-8.4 G08
0
50
25
25
75
125
R
PROG
= 19.6K
R
SENSE
= 0.2
V
BAT
= 6V
V
CC
= 9V
V
CC
(V)
9
V
PROG
(V)
10
11
12
1732-8.4 G09
2.48
2.47
2.46
2.45
2.44
R
PROG
= 19.6K
V
BAT
= 6V
T
A
= 25
TEMPERATURE (
C)
50
V
PROG
(V)
100
1732-8.4 G10
0
50
2.470
2.465
2.460
2.455
2.450
25
25
75
125
R
PROG
= 19.6k
V
CC
= 9V
TEMPERATURE (
C)
50
V
RECHRG
(V)
100
1732-8.4 G11
0
50
8.25
8.15
8.05
7.95
7.85
25
25
75
125
V
CC
= 9V
Battery Charge Current vs V
CC
Battery Charge Current vs
Temperature
Program Pin Voltage vs V
CC
Program Pin Voltage vs
Temperature
Recharge Threshold Voltage vs
Temperature
5
LTC1732-8.4
17328f
PI
N
FU
N
CTIO
N
S
U
U
U
BAT (Pin 1): Battery Sense Input. A bypass capacitor of
10
F 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 35
A 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)/(0.1
F). 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
800
)/(R
PROG
R
SENSE
). The IC can be forced
into shutdown 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.
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
< 30
A. Bypass this pin with a 1
F
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
800
)/(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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