1
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
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RATINGS
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PACKAGE/ORDER I
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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
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LTC1732-8.4
17328f
TYPICAL PERFOR A CE CHARACTERISTICS
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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
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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).
6
LTC1732-8.4
17328f
BLOCK DIAGRA
W
+
+
+
+
UVLO
UNDERVOLTAGE
LOCKOUT
V
CC
= 8.2V
ACPR
C1
+
C4
+
+
C3
A1
CA
C2
VA
CHARGE
GND
1732-8.4 BD
PROG
BATTERY CURRENT I
BAT
= (2.457V 800
)/(R
PROG
R
SENSE
)
R
PROG
V
REF
2.457V
LBO
80
V
CC
800
54mV
R
SENSE
SENSE
DRV
BAT
720
35
A
TIMER
OSCILLATOR
V
REF
COUNTER
STOP RECHRG
SHDN
SLP
C/10
C/10
2.5
A
V
CC
CHRG
5
6
3
4
ACPR
10
9
8
7
1
SEL*
2
+
+
C5
8.05V
*THE LTC1732-8.4 IS OPTIMIZED FOR 2-CELL (8.4V) Li-Ion BATTERIES.
CONNECT THE SEL PIN TO V
CC
. FOR CHARGING 8.2V BATTERIES USING
THE LTC1732, PLEASE CONTACT THE FACTORY
4.9V
7
LTC1732-8.4
17328f
OPERATIO
U
The LTC1732-8.4 is a linear battery charger controller. The
charge current is programmed by the combination of a
program resistor (R
PROG
) from the PROG pin to ground
and a sense resistor (R
SENSE
) between the V
CC
and SENSE
pins. R
PROG
sets a program current through an internal
trimmed 800
resistor setting up a voltage drop from V
CC
to the input of the current amplifier (CA). The current
amplifier servos the gate of the external P-channel MOSFET
to force the same voltage drop across R
SENSE
which sets
the charge current. When the voltage at the BAT pin
approaches the preset float voltage, the voltage amplifier
(VA) will start sinking current which shrinks the voltage
drop across R
SENSE
, thus reducing the charge current.
A charge cycle begins when the potential at V
CC
pin rises
above the UVLO level and a program resistor is connected
from the PROG pin to ground. At the beginning of the
charge cycle, if the battery voltage is below 4.9V, the
charger goes into trickle charge mode. The trickle charge
current is 10% of the full-scale current. If the battery
voltage stays low for one quarter of the total charge time,
the charge sequence will terminate.
The charger goes into the fast charge constant-current
mode after the voltage on the BAT pin rises above 4.9V. In
constant-current mode, the charge current is set by the
combination of R
SENSE
and R
PROG
.
When the battery approaches the final float voltage, the
charge current will begin to decrease. When the current
drops to 10% of the full-scale charge current, an internal
comparator will turn off the pull-down N-channel MOSFET
at the CHRG pin and connect a weak current source to
ground to indicate an end-of-charge (C/10) condition.
An external capacitor on the TIMER pin sets the total
charge time. After a time-out occurs, the charge cycle is
terminated and the CHRG pin is forced to a high imped-
ance state. To restart the charge cycle, remove the input
voltage and reapply it, or float the PROG pin momentarily.
Replacing the battery while in the charge mode will cause
the timer to be reset if the voltage of the new battery is
below 8.05V. If the voltage is above 8.05V, the timer will
continue for the remaining charge time. In the case when
a time out has occurred, a new battery with a voltage of
less than 8.05V can be inserted and charged automatically
with the full programmed charge time.
For batteries like lithium-ion that require accurate final
float voltage, the internal 2.457V reference, voltage ampli-
fier and the resistor divider provide regulation with
1%
(max) accuracy. For NiMH and NiCd batteries, the
LTC1732-8.4 can be used as a current source by pulling
the TIMER pin to V
CC
. When in the constant-current only
mode, the voltage amplifier, timer, C/10 comparator and
the trickle charge function are all disabled.
The charger can be shut down by floating the PROG
pin(I
CC
1mA). An internal current source will pull this pin
high and clamp it at 3.5V.
When the input voltage is not present, the charger goes
into a sleep mode, dropping I
CC
to 10
A. This greatly
reduces the current drain on the battery and increases the
standby time.
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LTC1732-8.4
17328f
APPLICATIO
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Charger Conditions
The charger is off when any of the following conditions exist:
the V
CC
pin is less than 8.2V, the dropout voltage (V
CC
V
BAT
) is less than 54mV, or the PROG pin is floating. The
DRV pin will be pulled to V
CC
and the internal resistor di-
vider is disconnected to reduce the current drain on the
battery.
Undervoltage Lockout (UVLO)
An internal undervoltage lockout circuit monitors the
input voltage and keeps the charger in shutdown mode
until V
CC
rises above 8.2V. To prevent oscillation around
V
CC
= 8.2V, the UVLO circuit has built-in hysteresis.
Trickle Charge and Defective Battery Detection
At the beginning of the charging sequence, if the battery
voltage is below 4.9V, the charger goes into trickle mode.
The charge current drops to 10% of the full-scale current.
If the low voltage persists for one quarter of the total
charge time, the battery is considered defective, the charge
cycle is terminated and the CHRG pin output is forced to
a high impedance state.
Shutdown
The LTC1732-8.4 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 thresh-
old voltage. The DRV pin is pulled up to V
CC
turning off the
external P-channel MOSFET. The internal timer is reset in
the shutdown mode.
Programming Charge Current
The formula for the battery charge current (see Block
Diagram) is:
I
BAT
= (I
PROG
)(800
/R
SENSE
)
= (2.457V/R
PROG
)(800
/R
SENSE
) or
R
PROG
= (2.457V/I
BAT
)(800
/R
SENSE
)
where R
PROG
is the total resistance from the PROG pin to
ground.
For example, if 0.5A charge current is needed, select a
value for R
SENSE
that will drop 100mV at the maximum
charge current. R
SENSE
= 0.1V/0.5A = 0.2
, then calculate:
R
PROG
= (2.457V/500mA)(800
/0.2
) = 19.656k
For best stability over temperature and time, 1% resistors
are recommended. The closest 1% resistor value is 19.6k.
Programming the Timer
The programmable timer terminates the charge cycle.
Typically, when charging at a 1C rate, a discharged Li-Ion
battery will become fully charged in 3 hours. For lower
charge current rates, extend the timer accordingly.The
length of the timer is programmed by an external capaci-
tor at the TIMER pin. The total charge time is:
Time (Hours) = (3 Hours) (C
TIMER
/0.1
F) or
C
TIMER
= 0.1
F Time (Hours)/3 (Hours)
The timer starts when an input voltage greater than 8.2V
is applied and the program resistor is connected to ground.
After a time-out occurs, the CHRG output will go into a
high impedance state to indicate that charging has stopped.
Connecting the TIMER pin to V
CC
disables the timer and
also puts the charger into a constant-current mode. To
only disable the timer function, short the TIMER pin to
GND.
CHRG Status Output Pin
When a charge cycle starts, the CHRG pin is pulled to
ground by an internal N-channel MOSFET that can drive an
LED. When the battery current drops to 10% of the full-
scale current (C/10), the N-channel MOSFET is turned off
and a weak 35
A current source to ground is connected to
the CHRG pin. After a time-out occurs, the pin will go into
a high impedance state. By using two different value pull-
up resistors, a microprocessor can detect three states
from this pin (charging, C/10 and stop charging). See
Figure 1 and Table 1.
9
LTC1732-8.4
17328f
APPLICATIO
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When the LTC1732-8.4 is in charge mode, the CHRG pin
is pulled low by an internal N-channel MOSFET. To detect
this mode, force the digital output pin, OUT, high and
measure the voltage at the CHRG pin. The N-channel
MOSFET will pull the pin low even with a 2k pull-up
resistor. Once the charge current drops to 10% of the full-
scale current (C/10), the N-channel MOSFET is turned off
and a 35
A current source is connected to the CHRG pin.
The IN pin is then pulled high by the 2k pull-up. By forcing
the OUT pin into a high impedance state, the current
source pulls the pin low through the 400k resistor. When
the internal timer has expired, the CHRG pin changes to
high impedance and the 400k resistor pulls the pin high to
indicate that charging has stopped.
ACPR Output Pin
The LTC1732-8.4 has an ACPR output pin to indicate that
the input supply (wall adapter) is higher than 8.2V and
55mV above the voltage at the BAT pin. When both
conditions are met, the ACPR pin is pulled to ground by an
N-channel MOSFET that is capable of driving an LED.
Otherwise, this pin is high impedance.
CHRG Status Output Pin (C/10)
The LTC1732-8.4 includes a comparator to monitor the
charge current to detect a near end-of-charge condition.
This comparator does not terminate the charge cycle, but
provides an output signal to indicate a near full charge
condition. The timer is used to terminate the charge cycle.
When the battery current falls below 10% of full scale, the
comparator trips and turns off the N-channel MOSFET at
the CHRG pin and switches in a 35
A current source to
ground. After an internal time delay of 15ms, this state is
latched. This delay helps prevent false triggering due to
transient currents. The end-of-charge comparator is dis-
abled in trickle charge mode.
Gate Drive
Typically the LTC1732-8.4 controls an external P-channel
MOSFET to supply current to the battery. An external PNP
transistor can also be used as the pass transistor instead
of the P-channel MOSFET. Due to the low current gain of
the current amplifier (CA), a high gain Darlington PNP
transistor is required to avoid excessive charge current
error. The gain of the current amplifier is around 0.6
A/
mV. For every 1
A of base current, a 1.6mV of gain error
shows up at the inputs of CA. With R
PROG
= 19.6k (100mV
across R
SENSE
), it represents 1.67% of error in charging
current.
Figure 1. Microprocessor Interface
2k
400k
CHRG
1732-8.4 F01
V
CC
V
DD
LTC1732-8.4
V
+
OUT
PROCESSOR
IN
3
8
Table 1. Microprocessor Interface
IN
OUT
CHARGE STATUS
LOW
HIGH
Charge
LOW
Hi-Z
C/10
HIGH
Hi-Z
Stop Charging
10
LTC1732-8.4
17328f
APPLICATIO
N
S I
N
FOR
M
ATIO
N
W
U
U
U
Constant-Current Only Mode
The LTC1732-8.4 can be used as a programmable current
source by connecting the TIMER pin to V
CC
. This is
particularly useful for charging NiMH or NiCd batteries. In
the constant-current only mode, the timer and voltage
amplifier are both disabled. An external termination method
is required to properly terminate the charge.
Battery Detection
The LTC1732-8.4 can detect the insertion of a new battery.
When a battery with voltage of less than 8.05V is inserted,
the LTC1732-8.4 resets the timer and a new charge cycle
begins. If the voltage of the new battery is above 8.05V, the
charging will not start if the TIMER has already timed out.
If a new battery (with a voltage above 8.05V) is inserted
while in the charging process, the timer will not be reset
and charging will continue until the timer runs out.
After a time out has occurred and the battery remains
connected, a new charge cycle will begin if the battery
voltage drops below 8.05V due to self-discharge or exter-
nal loading.
V
CC
Bypass Capacitor
Many types of capacitors can be used for input bypassing.
However, caution must be exercised when using multi-
layer ceramic capacitors. Because of the self resonant and
high Q characteristics of some types of ceramic capaci-
tors, high voltage transients can be generated under some
start-up conditions, such as connecting the charger input
to a hot power source. To minimize these transients, only
ceramic capacitors with X5R or X7R dielectric are recom-
mended. Also, adding 1
or 2
in series with the ceramic
capacitor will further reduce these start-up transients. For
more information refer to Application Note 88.
Stability
The charger is stable without any compensation when a
P-channel MOSFET is used as the pass transistor.
However, a 10
F capacitor is recommended at the BAT
pin to keep the ripple voltage low when the battery is
disconnected.
If a PNP transistor is used for the pass transistor, a 1000pF
capacitor is required from the DRV pin to V
CC
. This
capacitor is needed to help stablize the voltage loop. A
10
F capacitor at the BAT pin is also recommended when
a battery is not present.
11
LTC1732-8.4
17328f
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.
MS Package
10-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1661)
MSOP (MS) 1001
0.53
0.01
(.021
.006)
SEATING
PLANE
0.18
(.007)
1.10
(.043)
MAX
0.17 0.27
(.007 .011)
0.13
0.05
(.005
.002)
0.86
(.034)
REF
0.50
(.0197)
TYP
1 2 3 4 5
4.88
0.10
(.192
.004)
0.497
0.076
(.0196
.003)
REF
8
9
10
7 6
3.00
0.102
(.118
.004)
(NOTE 3)
3.00
0.102
(.118
.004)
NOTE 4
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") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
0.254
(.010)
0
6
TYP
DETAIL "A"
DETAIL "A"
GAUGE PLANE
5.23
(.206)
MIN
3.2 3.45
(.126 .136)
0.889
0.127
(.035
.005)
RECOMMENDED SOLDER PAD LAYOUT
WITHOUT EXPOSED PAD OPTION
3.05
0.38
(.0120
.0015)
TYP
0.50
(.0197)
BSC
U
PACKAGE DESCRIPTIO
12
LTC1732-8.4
17328f
PART NUMBER
DESCRIPTION
COMMENTS
LT
1510-5
500kHz Constant-Voltage/Constant-Current Battery Charger
Most Compact, Up to 1.5A, Charges NiCd, NiMH, Li-Ion Cells
LT1512
SEPIC Battery Charger
V
IN
Can Be Higher or Lower Than Battery Voltage, 1.5A Switch
LTC1571-1/
200kHz/500kHz 1.5A Constant-Current/Constant-Voltage
Charges 1- or 2-Cell Li-Ion Batteries, Preset and Adjustable
LTC1571-2/
Battery Charger
Battery Voltages, C/10 Charge Detection
LTC1571-5
LT1620
Rail-to-Rail Current Sense Amplifier
Precise Output Current Programming, Up to 32V
OUT
, Up to 10A I
OUT
LTC1729
Termination Controller for Li-Ion
Time or Charge Current Termination, Automatic Charger/Battery
Detection, Status Output, Preconditioning, 8-Lead MSOP
LTC1730/
Complete Li-Ion Pulse Battery Charger with Internal FET
Efficient 1.5A Charger with Many Features Including
LTC4052
and Thermal Regulation
Overcurrent Battery Protection
LTC1731
Complete Li-Ion Linear Battery Charger Controller
Single Cell and 2-Cell Li-Ion, C/10 Detection, Complete Charger
LTC1732-4/
Complete Linear Battery Charger Controller
No Firmware Required, AC Adapter Indicator
LTC1732-4.2
for Single Cell Li-Ion Battery
Automatic Charge and Recharge
LTC1733
CompleteLi-Ion Linear Battery Charger with Internal FET
1.5A Charger with Many Features Including Thermal Feedback for
Increased Charge Current without Exceeding Maximum Temperature
LTC1734/
ThinSOT Li-Ion Linear Charger
Only Two External Components, V
PROG
Tracks I
CHARGE
LTC1734L
No Diode Needed, No Sense Resistor Needed,
50mA to 700mA Charge Current
LTC4050
Complete Li-Ion Linear Charger with Thermistor Interface
No Firmware Required, AC Adapter Indicator
Automatic Charge and Recharge
LTC4053
USB Compatible Li-Ion Linear Battery Charger
Operate from Wall Adapter Input and/or USB Input, 100mA/500mA up
to 1.25A Charge Current, Thermal Limit Prevent Over Heating,
Standalone Charger.
LTC4412
Low Loss PowerPath
TM
Controller in ThinSOT
TM
Automatic Switching Between DC Sources, Load Sharing,
Replaces ORing Diodes
ThinSot and PowerPath are trademarks of Linear Technology Corporation.
RELATED PARTS
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
q
FAX: (408) 434-0507
q
www.linear.com
U
TYPICAL APPLICATIO
SEL
V
CC
V
IN
= 10V
SENSE
DRV
R2
2k
R
SENSE
0.25
R1
10k
R
PROG
19.6k
2-CELL
Li-ION
LTC1732-8.4
BAT
CHRG
9
8
2
MBRM120T3
C2
10
F
C1
1nF
1732 TA02
C3
1
F
I
BAT
= 400mA
C
TIMER
*
0.1
F
Q1
2N5087
7
1
6
5
3
4
TIMER
PROG
GND
Q2
ZTX749
*AVX 0603ZC104KAT1A
+
CHARGE
STATUS
ACPR
2k
10
2-Cell 8.4V Linear Charger Using a PNP Pass Transistor
LINEAR TECHNOLOGY CORPORATION 2001
LT/TP 0203 2K PRINTED IN THE USA
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