LTC1732-8.4 [Linear]
Lithium-Ion Linear Battery Charger Controller; 锂离子电池线性充电器，控制器
| 型号： | LTC1732-8.4 |
| 厂家： | 
Linear |
| 描述： | Lithium-Ion Linear Battery Charger Controller |
| 文件： | 总12页 (文件大小：150K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC1732-8.4
Lithium-Ion Linear
Battery Charger Controller
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DESCRIPTIO
FEATURES
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)andnickelmetal-
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
andprecisionreferencesetthefinalfloatvoltagewith±1%
accuracy.
■
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
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.
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
■
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APPLICATIO S
The LTC1732-8.4 begins a new charge cycle when a
dischargedbatteryisconnectedtothechargerorwhenthe
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.
■
Cellular Phones
■
Handheld Computers
■
Charging Docks and Cradles
■
Digital Cameras and Camcorders
, LTC and LT are registered trademarks of Linear Technology Corporation.
TheLTC1732-8.4isavailableinthe10-pinMSOPpackage.
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TYPICAL APPLICATIO
400mA 2-Cell 8.4V Li-Ion Battery Charger
Typical Li-Ion Charge Cycle
V
IN
= 10V
9
CONSTANT
CURRENT
CONSTANT
VOLTAGE
MBRM120T3
2
8
BATTERY VOLTAGE
R1
1k
R2
1k
R
SENSE
SEL
V
1µF
CC
0.25Ω
400
300
200
100
0
8
7
6
9
7
400mA HR BATTERY
SENSE
DRV
3
Q1
Si9430DY
CHRG
CHARGE CURRENT
LTC1732-8.4
I
= 400mA
BAT
10
4
1
6
ACPR
BAT
CHRG
LED OFF
TIMER
TIMER
STOPS
PROG
C
+
TIMER
0.1µF
8.4V
Li-Ion
BATTERY
GND
R
*
PROG
19.6k
10µF
5
2.0
TIME (HOURS)
3.0
0
0.5
1.0
1.5
2.5
1732-8.4 TA01
*SHUTDOWN INVOKED BY FLOATING THE PROG PIN
1732-8.4 TA01b
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LTC1732-8.4
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ABSOLUTE MAXIMUM RATINGS
PACKAGE/ORDER INFORMATION
(Note 1)
Input Supply Voltage (VCC) ................................... 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
TOP VIEW
BAT
SEL
CHRG
TIMER
GND
1
2
3
4
5
10 ACPR
LTC1732EMS-8.4
9
8
7
6
SENSE
V
CC
DRV
PROG
MS10 PART MARKING
LTWW
MS10 PACKAGE
10-LEAD PLASTIC MSOP
TJMAX = 140°C, θJA = 180°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 9V unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
Input Supply Voltage
Input Supply Current
●
8.8
12
V
CC
I
Charger On, Current Mode
Shutdown Mode
Sleep Mode (Battery Drain Current)
●
●
1
1
10
3
3
30
mA
mA
µA
CC
V
Regulated Output Float Voltage
Current Mode Charge Current
9V ≤ V ≤ 12V, V
= V
CC
●
●
8.316
8.4
8.484
V
BAT
CC
SEL
I
R
R
= 19.6k, R
= 19.6k, R
= 0.2Ω
= 0.2Ω
465
415
500
535
585
mA
mA
BAT
PROG
PROG
SENSE
SENSE
R
= 97.6k, R
= 0.2Ω
60
30
100
50
140
125
5.1
8.7
mA
mA
V
PROG
SENSE
I
Trickle Charge Current
V
= 4V, R
= 19.6k, I
= (V – V )/0.2Ω
SENSE
●
●
●
TRIKL
BAT
PROG
TRIKL
CC
V
V
Trickle Charge Threshold Voltage
From Low to High
From Low to High
4.7
4.9
8.2
400
TRIKL
UV
V
V
Undervoltage Lockout Voltage
Undervoltage Lockout Hysteresis
V
CC
CC
∆V
mV
UV
V
V
V
Manual Shutdown Threshold Voltage
PROG Pin Low to High
PROG Pin High to Low
2.457
2.446
V
V
MSD
Automatic Shutdown Threshold Voltage
(V – V ) High to Low
30
40
54
69
90
100
mV
mV
ASD
CC
BAT
(V – V ) Low to High
CC
BAT
Voltage Mode Disable Threshold Voltage
PROG Pin Current
V
= V – V
TIMER
0.4
V
DIS
DIS
CC
I
Internal Pull-Up Current, No R
PROG Pin Source Current, ∆V
2.5
µA
µA
PROG
PROG
≤ 5mV
●
300
PROG
V
V
PROG Pin Voltage
R
=19.6k
PROG
2.457
0.6
35
V
V
PROG
ACPR
CHRG
ACPR Pin Output Low Voltage
CHRG Pin Weak Pull-Down Current
CHRG Pin Output Low Voltage
Drive Pin Current
I
= 5mA
1.2
55
ACPR
I
V
= 1V
15
µA
V
CHRG
CHRG
V
I
= 5mA
0.6
26
1.2
CHRG
I
V
= V – 2V
µA
DRV
DRV
CC
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LTC1732-8.4
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCC = 9V unless otherwise noted.
SYMBOL PARAMETER CONDITIONS
MIN
TYP
50
MAX
UNITS
mA
%
I
t
10% Charge Current Indication Level
TIMER Accuracy
R
= 19.6k, R = 0.2Ω
SENSE
●
25
100
C/10
PROG
C
V
= 0.1µF
10
TIMER
TIMER
VRECHRG
Recharge Threshold Voltage
from High to Low
7.85
8.05
V
BAT
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.
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TYPICAL PERFOR A CE CHARACTERISTICS
Trickle Charge Current vs
Temperature
Trickle Charge Threshold Voltage
vs VCC
Trickle Charge Current vs VCC
60
55
50
45
40
4.96
4.95
4.94
4.93
4.92
4.91
4.90
4.89
4.88
60
55
50
45
40
R
R
= 19.6K
PROG
R
T
= 19.6K
PROG
A
R
R
= 19.6K
PROG
= 0.2Ω
SENSE
= 25°
= 0.2Ω
SENSE
V
V
= 4V
BAT
CC
V
T
= 4V
BAT
= 9V
= 25°
A
–25
0
25
50
75
125
–50
100
9
10
11
12
9
10
11
12
TEMPERATURE (°C)
V
CC
(V)
V
CC
(V)
1732-8.4 G02
1732-8.4 G03
1732-8.4 G01
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LTC1732-8.4
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TYPICAL PERFOR A CE CHARACTERISTICS
Trickle Charge Threshold Voltage
vs Temperature
Timer Accuracy vs Temperature
Timer Accuracy vs VCC
110
105
100
95
4.94
4.93
4.92
4.91
4.90
110
105
100
95
C
V
A
= 0.1µF
C
= 0.1µF
TIMER
V
= 9V
TIMER
BAT
CC
= 6V
V
= 9V
CC
T
= 25°
90
–50
90
–25
0
25
50
75
125
100
–25
0
25
50
75
125
9
10
11
12
–50
100
V
CC
(V)
TEMPERATURE (°C)
TEMPERATURE (°C)
1732-8.4 G06
1732-8.4 G05
1732-8.4 G04
Battery Charge Current vs
Temperature
Program Pin Voltage vs VCC
Battery Charge Current vs VCC
540
530
520
510
500
490
480
470
460
520
510
500
490
480
2.48
2.47
2.46
2.45
2.44
R
R
= 19.6K
R
R
= 19.6K
PROG
R
V
= 19.6K
PROG
PROG
= 0.2Ω
= 0.2Ω
SENSE
= 6V
BAT
SENSE
V
V
= 6V
V
= 6V
BAT
= 9V
CC
T = 25°
A
BAT
T
= 25°
A
–25
0
25
50
75
125
–50
100
9
10
11
12
9
10
11
12
V
(V)
V
CC
(V)
TEMPERATURE (°C)
CC
1732-8.4 G08
1732-8.4 G07
1732-8.4 G09
Program Pin Voltage vs
Temperature
Recharge Threshold Voltage vs
Temperature
8.25
8.15
8.05
7.95
7.85
2.470
2.465
2.460
2.455
2.450
V
CC
= 9V
R
CC
= 19.6k
PROG
V
= 9V
–25
0
25
50
75
125
–25
0
25
50
75
125
–50
100
–50
100
TEMPERATURE (°C)
TEMPERATURE (°C)
1732-8.4 G11
1732-8.4 G10
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LTC1732-8.4
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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.
PROG (Pin 6): Charge Current Program and Shutdown
Input Pin. The charge current is programmed by connect-
ing a resistor, RPROG to ground. The charge current is IBAT
= (VPROG • 800Ω)/(RPROG • RSENSE). 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.
SEL (Pin 2): This pin must be connected to VCC.
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).
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.
VCC (Pin 8): Input Supply Voltage. VCC can range from
8.8Vto12V. IfVCC dropsbelowVBAT +54mV, forexample
when the input supply is disconnected, then the IC enters
sleep mode with ICC < 30µA. Bypass this pin with a 1µF
capacitor.
SENSE (Pin 9): Current Sense Input. A sense resistor,
RSENSE, must be connected from VCC to the SENSE pin.
This resistor is chosen using the following equation:
TIMER (Pin 4): Timer Capacitor and Constant-Voltage
Mode Disable Input Pin. The timer period is set by placing
a capacitor, CTIMER, to GND. The timer period is tTIMER
=
RSENSE = (VPROG • 800Ω)/(RPROG • IBAT
)
(CTIMER • 3 hours)/(0.1µF). When the TIMER pin is
connectedtoVCC, thetimerisdisabled, thustheconstant-
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.
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).
GND (Pin 5): Ground.
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LTC1732-8.4
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BLOCK DIAGRA
V
CC
8
8.05V
+
–
UNDERVOLTAGE
LOCKOUT
C5
V
= 8.2V
CC
R
SENSE
SENSE
+
–
9
800Ω
C1
80Ω
+
54mV
–
CHRG
+
–
3
C4
–
+
C/10 STOP RECHRG C/10
720Ω
DRV
BAT
35µA
CA
7
1
ACPR
SHDN
UVLO
–
+
SLP
C2
LBO
TIMER
ACPR
OSCILLATOR
COUNTER
4
4.9V
SEL*
2
V
REF
–
+
10
+
+
VA
V
CC
V
REF
2.457V
C3
A1
–
–
2.5µA
CHARGE
PROG
GND
6
5
1732-8.4 BD
BATTERY CURRENT I
BAT
= (2.457V • 800Ω)/(R
• R
)
SENSE
PROG
R
PROG
*THE LTC1732-8.4 IS OPTIMIZED FOR 2-CELL (8.4V) Li-Ion BATTERIES.
CONNECT THE SEL PIN TO V . FOR CHARGING 8.2V BATTERIES USING
CC
THE LTC1732, PLEASE CONTACT THE FACTORY
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LTC1732-8.4
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OPERATIO
TheLTC1732-8.4isalinearbatterychargercontroller.The
charge current is programmed by the combination of a
program resistor (RPROG) from the PROG pin to ground
and a sense resistor (RSENSE) between the VCC and SENSE
pins. RPROG sets a program current through an internal
trimmed 800Ω resistor setting up a voltage drop from VCC
to the input of the current amplifier (CA). The current
amplifierservosthegateoftheexternalP-channelMOSFET
to force the same voltage drop across RSENSE 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 RSENSE, thus reducing the charge current.
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 VCC. When in the constant-current only
mode, the voltage amplifier, timer, C/10 comparator and
the trickle charge function are all disabled.
A charge cycle begins when the potential at VCC 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 can be shut down by floating the PROG
pin(ICC ≈1mA). An internal current source will pull this pin
high and clamp it at 3.5V.
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
When the input voltage is not present, the charger goes
into a sleep mode, dropping ICC to 10µA. This greatly
reduces the current drain on the battery and increases the
standby time.
combination of RSENSE and RPROG
.
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
comparatorwillturnoffthepull-downN-channelMOSFET
at the CHRG pin and connect a weak current source to
ground to indicate an end-of-charge (C/10) condition.
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LTC1732-8.4
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APPLICATIONS INFORMATION
Charger Conditions
For example, if 0.5A charge current is needed, select a
value for RSENSE that will drop 100mV at the maximum
chargecurrent.RSENSE =0.1V/0.5A=0.2Ω,thencalculate:
Thechargerisoffwhenanyofthefollowingconditionsexist:
the VCC pin is less than 8.2V, the dropout voltage (VCC
–
VBAT) is less than 54mV, or the PROG pin is floating. The
DRV pin will be pulled to VCC and the internal resistor di-
vider is disconnected to reduce the current drain on the
battery.
RPROG = (2.457V/500mA)(800Ω/0.2Ω) = 19.656k
For best stability over temperature and time, 1% resistors
are recommended. The closest 1% resistor value is 19.6k.
Programming the Timer
Undervoltage Lockout (UVLO)
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:
An internal undervoltage lockout circuit monitors the
input voltage and keeps the charger in shutdown mode
until VCC rises above 8.2V. To prevent oscillation around
VCC = 8.2V, the UVLO circuit has built-in hysteresis.
Trickle Charge and Defective Battery Detection
Time (Hours) = (3 Hours) • (CTIMER/0.1µF) or
CTIMER = 0.1µF • Time (Hours)/3 (Hours)
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
chargetime,thebatteryisconsidereddefective,thecharge
cycle is terminated and the CHRG pin output is forced to
a high impedance state.
The timer starts when an input voltage greater than 8.2V
isappliedandtheprogramresistorisconnectedtoground.
After a time-out occurs, the CHRG output will go into a
highimpedancestatetoindicatethatcharginghasstopped.
Connecting the TIMER pin to VCC 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.
Shutdown
The LTC1732-8.4 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 thresh-
old voltage. The DRV pin is pulled up to VCC turning off the
external P-channel MOSFET. The internal timer is reset in
the shutdown mode.
CHRG Status Output Pin
When a charge cycle starts, the CHRG pin is pulled to
groundbyaninternalN-channelMOSFETthatcandrivean
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 35µA 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.
Programming Charge Current
The formula for the battery charge current (see Block
Diagram) is:
IBAT = (IPROG)(800Ω/RSENSE
)
= (2.457V/RPROG)(800Ω/RSENSE) or
RPROG = (2.457V/IBAT)(800Ω/RSENSE
)
where RPROG is the total resistance from the PROG pin to
ground.
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APPLICATIONS INFORMATION
+
V
V
DD
ACPR Output Pin
8
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.
V
CC
400k
2k
µPROCESSOR
3
CHRG
LTC1732-8.4
OUT
IN
1732-8.4 F01
Figure 1. Microprocessor Interface
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 35µA 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.
Table 1. Microprocessor Interface
IN
OUT
HIGH
Hi-Z
CHARGE STATUS
Charge
LOW
LOW
HIGH
C/10
Hi-Z
Stop Charging
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 35µA 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.
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 0.6µA/
mV. For every 1µA of base current, a 1.6mV of gain error
shows up at the inputs of CA. With RPROG = 19.6k (100mV
across RSENSE), it represents 1.67% of error in charging
current.
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APPLICATIONS INFORMATION
Constant-Current Only Mode
VCC Bypass Capacitor
TheLTC1732-8.4canbeusedasaprogrammablecurrent
source by connecting the TIMER pin to VCC. This is
particularlyusefulforchargingNiMHorNiCdbatteries. In
the constant-current only mode, the timer and voltage
amplifierarebothdisabled.Anexternalterminationmethod
is required to properly terminate the charge.
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 1Ω or 2Ω in series with the ceramic
capacitor will further reduce these start-up transients. For
more information refer to Application Note 88.
Battery Detection
TheLTC1732-8.4candetecttheinsertionofanewbattery.
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. Ifthevoltageofthenewbatteryisabove8.05V, 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.
Stability
The charger is stable without any compensation when a
P-channel MOSFET is used as the pass transistor.
However, a 10µF capacitor is recommended at the BAT
pin to keep the ripple voltage low when the battery is
disconnected.
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.
IfaPNPtransistorisusedforthepasstransistor,a1000pF
capacitor is required from the DRV pin to VCC. This
capacitor is needed to help stablize the voltage loop. A
10µF capacitor at the BAT pin is also recommended when
a battery is not present.
17328f
10
LTC1732-8.4
U
PACKAGE DESCRIPTIO
MS Package
10-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1661)
0.889 ± 0.127
(.035 ± .005)
5.23
(.206)
MIN
3.2 – 3.45
(.126 – .136)
3.00 ± 0.102
(.118 ± .004)
(NOTE 3)
0.497 ± 0.076
(.0196 ± .003)
0.50
3.05 ± 0.38
(.0120 ± .0015)
TYP
(.0197)
10 9
8
7 6
BSC
REF
RECOMMENDED SOLDER PAD LAYOUT
WITHOUT EXPOSED PAD OPTION
3.00 ± 0.102
(.118 ± .004)
NOTE 4
4.88 ± 0.10
(.192 ± .004)
DETAIL “A”
0.254
(.010)
0° – 6° TYP
GAUGE PLANE
1
2
3
4 5
0.53 ± 0.01
(.021 ± .006)
0.86
(.034)
REF
1.10
(.043)
MAX
DETAIL “A”
0.18
(.007)
SEATING
PLANE
0.17 – 0.27
(.007 – .011)
0.13 ± 0.05
(.005 ± .002)
MSOP (MS) 1001
0.50
(.0197)
TYP
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
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-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
11
LTC1732-8.4
U
TYPICAL APPLICATIO
2-Cell 8.4V Linear Charger Using a PNP Pass Transistor
V
IN
= 10V
MBRM120T3
R2
2k
C1
1nF
R1
10k
R
C3
1µF
SENSE
0.25Ω
CHARGE
2
SEL
8
STATUS
V
CC
Q2
ZTX749
2k
3
10
4
9
7
CHRG
LTC1732-8.4
SENSE
Q1
2N5087
DRV
ACPR
I
= 400mA
BAT
1
6
BAT
TIMER
PROG
C
*
TIMER
0.1µF
+
GND
C2
10µF
R
PROG
19.6k
2-CELL
Li-ION
5
1732 TA02
*AVX 0603ZC104KAT1A
RELATED PARTS
PART NUMBER
LT®1510-5
LT1512
DESCRIPTION
COMMENTS
500kHz Constant-Voltage/Constant-Current Battery Charger Most Compact, Up to 1.5A, Charges NiCd, NiMH, Li-Ion Cells
SEPIC Battery Charger
V Can Be Higher or Lower Than Battery Voltage, 1.5A Switch
IN
LTC1571-1/
LTC1571-2/
LTC1571-5
200kHz/500kHz 1.5A Constant-Current/Constant-Voltage
Battery Charger
Charges 1- or 2-Cell Li-Ion Batteries, Preset and Adjustable
Battery Voltages, C/10 Charge Detection
LT1620
Rail-to-Rail Current Sense Amplifier
Termination Controller for Li-Ion
Precise Output Current Programming, Up to 32V , Up to 10A I
OUT
OUT
LTC1729
Time or Charge Current Termination, Automatic Charger/Battery
Detection, Status Output, Preconditioning, 8-Lead MSOP
LTC1730/
LTC4052
Complete Li-Ion Pulse Battery Charger with Internal FET
and Thermal Regulation
Efficient 1.5A Charger with Many Features Including
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/
LTC1732-4.2
Complete Linear Battery Charger Controller
for Single Cell Li-Ion Battery
No Firmware Required, AC Adapter Indicator
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/
LTC1734L
ThinSOT Li-Ion Linear Charger
Only Two External Components, V
No Diode Needed, No Sense Resistor Needed,
50mA to 700mA Charge Current
Tracks I
PROG CHARGE
LTC4050
LTC4053
Complete Li-Ion Linear Charger with Thermistor Interface
USB Compatible Li-Ion Linear Battery Charger
No Firmware Required, AC Adapter Indicator
Automatic Charge and Recharge
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 PowerPathTM Controller in ThinSOTTM
Automatic Switching Between DC Sources, Load Sharing,
Replaces ORing Diodes
ThinSot and PowerPath are trademarks of Linear Technology Corporation.
17328f
LT/TP 0203 2K • PRINTED IN THE USA
12 LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
●
●
LINEAR TECHNOLOGY CORPORATION 2001
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
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