LINER LTC1731EMS8-8.4 Lithium-ion linear battery charger controller Datasheet

LTC1731-8.2/LTC1731-8.4
Lithium-Ion Linear
Battery Charger Controller
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FEATURES
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DESCRIPTIO
The LTC ®1731-8.2/LTC1731-8.4 are complete constantcurrent/constant-voltage linear charger controllers for 2cell lithium-ion (Li-Ion)batteries. Nickel-cadmium (NiCd)
and nickel-metal-hydride (NiMH) batteries can also be
charged with constant current using external termination. The external sense resistor sets the charge current
with 7% accuracy. An internal resistor divider and precision reference set the final float potential with 1% accuracy. The output float voltages are set internally to 8.2V
(LTC1731-8.2) or 8.4V (LTC1731-8.4).
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 (15µA Battery Drain)
Automatic Trickle Charging of Low Voltage Cells
Programmable for Constant-Current-Only Mode
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 15µA. An
internal comparator detects the end-of-charge (C/10) condition while a programmable 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 4.95V.
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APPLICATIO S
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Cellular Phones
Handheld Computers
Charging Docks and Cradles
Programmable Current Source
The LTC1731-8.2/LTC1731-8.4 are available in the 8-pin
MSOP and SO packages. For 1-cell Li-Ion battery charging, see the LTC1731-4.1 and LTC1731-4.2 data sheets.
, LTC and LT are registered trademarks of Linear Technology Corporation.
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TYPICAL APPLICATIO
400mA Li-Ion Charger
Typical Li-Ion Charge Cycle
VIN = 9V
CONSTANT
CURRENT
CHARGE
STATUS
VCC
SENSE
2
DRV
CHRG
RSENSE
0.2Ω
8
6
Q1
Si9430DY
LTC1731-8.4
3
CTIMER
0.1µF
TIMER
BAT
PROG
GND
4
1µF
IBAT = 400mA
1
5
RPROG*
19.6k
+ 2-CELL
BATTERY VOLTAGE
400
8
400mA HR BATTERY
300
CHARGE CURRENT
200
CHRG
LED OFF
100
7
TIMER
STOPS
10µF
Li-ION
0
1731 TA01
*SHUTDOWN INVOKED BY FLOATING THE PROG PIN
9
CONSTANT
VOLTAGE
BATTERY VOLTAGE(V)
7
2k
CHARGE CURRENT (mA)
MBRM120T3
0
0.5
2.0
1.5
1.0
TIME (HOURS)
2.5
6
3.0
1731 TA01b
sn1731 17318fs
1
LTC1731-8.2/LTC1731-8.4
W W
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ABSOLUTE MAXIMUM RATINGS
(Note 1)
Input Supply Voltage (VCC) ................................... 13.2V
SENSE, DRV, BAT, TIMER, PROG ............ – 0.3V to VCC
CHRG ..................................................... – 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
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PACKAGE/ORDER INFORMATION
ORDER PART
NUMBER
TOP VIEW
BAT
CHRG
TIMER
GND
1
2
3
4
8
7
6
5
SENSE
VCC
DRV
PROG
LTC1731EMS8-8.2
LTC1731EMS8-8.4
MS8 PACKAGE
8-LEAD PLASTIC MSOP
MS8 PART MARKING
TJMAX = 150°C, θJA = 200°C/W
LTSW
LTPE
ORDER PART
NUMBER
TOP VIEW
BAT 1
8
SENSE
CHRG 2
7
VCC
TIMER 3
6
DRV
GND 4
5
PROG
LTC1731ES8-8.2
LTC1731ES8-8.4
S8 PART MARKING
S8 PACKAGE
8-LEAD PLASTIC SO
173182
173184
TJMAX = 150°C, θJA = 125°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
VCC
Input Supply Voltage
CONDITIONS
MIN
ICC
Input Supply Current
Charger On, Current Mode
Shutdown Mode
Sleep Mode (Battery Drain Current)
●
●
VBAT
Regulated Output Voltage
LTC1731-8.2 (9V ≤ VCC ≤ 12V)
LTC1731-8.4 (9V ≤ VCC ≤ 12V)
●
●
IBAT
Current Mode Charge Current
RPROG = 19.6k, RSENSE = 0.2Ω
RPROG = 19.6k, RSENSE = 0.2Ω
RPROG = 97.6k, RSENSE = 0.2Ω
●
●
TYP
8.8
MAX
UNITS
12
V
1
1
15
3
2
30
mA
mA
µA
8.118
8.316
8.2
8.4
8.282
8.484
465
415
70
500
500
100
535
585
130
mA
mA
mA
V
V
ITRIKL
Trickle Charge Current
VBAT = 4V, RPROG = 19.6k, ITRIKL = (VCC – VSENSE)/0.2Ω
●
30
50
100
mA
VTRIKL
Trickle Charge Threshold Voltage
BAT Rising
●
4.7
4.95
5.1
V
VUV
VCC Undervoltage Lockout Voltage
VCC Rising
●
8.2
8.8
V
∆VUV
VCC Undervoltage Lockout Hysteresis
VCC Falling
VMSD
Manual Shutdown Threshold Voltage
PROG Pin Rising
PROG Pin Falling
2.457
2.446
V
V
IDRV
Drive Pin Current
VDRV = VCC – 2V
26
µA
200
mV
sn1731 17318fs
2
LTC1731-8.2/LTC1731-8.4
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
VASD
Automatic Shutdown Threshold Voltage
(VCC – VBAT) Falling
(VCC – VBAT) Rising
MIN
TYP
MAX
UNITS
30
40
54
69
90
100
mV
mV
VDIS
Voltage Mode Disable Threshold Voltage
VDIS = (VCC – VTIMER)
0.4
V
IPROG
PROG Pin Current
Internal Pull-Up Current, No RPROG
PROG Pin Load Regulation
PROG Pin Source Current, ∆VPROG ≤ 5mV
VPROG
PROG Pin Voltage
RPROG =19.6k
ICHRG
CHRG Pin Weak Pull-Down Current
VCHRG = 1V
VCHRG
CHRG Pin Output Low Voltage
ICHRG = 5mA
IC/10
End of Charge Indication Current Level
RPROG = 19.6k, RSENSE = 0.2Ω
tTIMER
TIMER Accuracy
CTIMER = 0.01µF
10
%
VCLAMP
DRV Pin Clamp Voltage
VCLAMP = VCC – VDRV, IDRIVE = 50µA
6.5
V
●
µA
2.5
●
µA
300
2.457
50
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
●
25
V
100
150
µA
0.6
1.2
V
50
100
mA
Note 2: The LTC1731E-8.2/LTC1731E-8.4 are 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. Consult
factory for I grade parts.
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TYPICAL PERFOR A CE CHARACTERISTICS
Trickle Charge Current
vs Temperature
60
55
ITRKL (mA)
55
ITRKL (mA)
60
RPROG = 19.6K
RSENSE = 0.2Ω
VBAT = 4V
TA = 25°
50
Trickle Charge Threshold Voltage
vs VCC
4.96
RPROG = 19.6K
RSENSE = 0.2Ω
VBAT = 4V
VCC = 9V
4.94
50
4.93
4.92
4.91
45
45
RPROG = 19.6K
TA = 25°
4.95
VTRKL (V)
Trickle Charge Current
vs VCC
4.90
4.89
40
9
10
11
12
VCC (V)
40
–50 –25
0
25
50
75
100
125
9
10
11
12
VCC (V)
TEMPERATURE (°C)
1731 G01
4.88
1731 G06
1731 G08
sn1731 17318fs
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LTC1731-8.2/LTC1731-8.4
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TYPICAL PERFOR A CE CHARACTERISTICS
Trickle Charge Threshold Voltage
vs Temperature
Timer Accuracy vs VCC
4.94
110
VCC = 9V
CTIMER = 0.1µF
VBAT = 6V
TA = 25°
CTIMER = 0.1µF
VCC = 9V
105
4.92
4.91
tTIMER (%)
105
tTIMER (%)
VTRKL (V)
4.93
Timer Accuracy vs Temperature
110
100
95
95
4.90
–50 –25
25
0
75
50
100
90
125
9
10
11
75
540
530
520
125
Program Pin Voltage
vs VCC
2.48
RPROG = 19.6K
RSENSE = 0.2Ω
VBAT = 6V
VCC = 9V
RPROG = 19.6K
VBAT = 6V
TA = 25°
2.47
510
VPROG (V)
RPROG = 19.6K
RSENSE = 0.2Ω
VBAT = 6V
TA = 25°
100
1731 G04
Battery Charge Current
vs Temperature
IBAT (mA)
IBAT (mA)
50
1731 G05
Battery Charge Current
vs VCC
500
25
0
TEMPERATURE (°C)
1731 G03
510
90
–50 –25
12
VCC (V)
TEMPERATURE (°C)
520
100
500
2.46
490
490
2.45
480
470
480
9
10
11
460
–50 –25
12
VCC (V)
2.44
0
25
50
75
100
125
1731 G09
9
10
11
12
VCC (V)
TEMPERATURE (°C)
1731 G07
1731 G10
Program Pin Voltage
vs Temperature
2.470
RPROG = 19.6k
VCC = 9V
VPROG (V)
2.465
2.460
2.455
2.450
–50 –25
0
25
50
75
100
125
TEMPERATURE (°C)
1731 G02
sn1731 17318fs
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LTC1731-8.2/LTC1731-8.4
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PIN FUNCTIONS
BAT (Pin 1): Battery Sense Input. A bypass capacitor of at
least 10µF is required to keep the loop stable when the
battery is not connected. A precision internal resistive
divider sets the final float potential on this pin. The resistor
divider is disconnected in sleep mode.
CHRG (Pin 2): Open-Drain Charge Status Output. When
the battery is being charged, 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 at least 0.32
seconds, the N-channel MOSFET turns off and a 100µA
current source is connected from the CHRG pin to GND.
When the timer runs out or the input supply is removed,
the current source will be disconnected and the CHRG pin
is forced into a high impedance state.
TIMER (Pin 3): Timer Capacitor and Constant-Voltage
Mode Disable Input Pin. A capacitor CTIMER connected
from this pin to ground sets a 30 hour/µF time period for
charge termination. When the TIMER pin is connected to
VCC, the constant-voltage mode and the timer is disabled
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.
GND (Pin 4): Ground.
PROG (Pin 5): Charge Current Program and Shutdown
Input Pin. The charge current is programmed by connecting 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.
DRV (Pin 6): 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). The DRV
pin is internally clamped to 6.5V below VCC.
VCC (Pin 7): Input Supply Voltage. VCC ranges from 8.8V
to 12V when charging. If VCC drops below VBAT + 54mV,
for example when the input supply is disconnected, then
the IC enters sleep mode with ICC < 30µA. Bypass this pin
with a 1µF capacitor.
SENSE (Pin 8): Current Sense Input. Connect this pin to
the sense resistor. Choose the resistor value using the
following equation:
RSENSE = (VPROG • 800Ω)/(RPROG • IBAT)
sn1731 17318fs
5
LTC1731-8.2/LTC1731-8.4
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BLOCK DIAGRA
VCC
7
RSENSE
SENSE
+
80Ω
C1
2
+
–
800Ω
–
CHRG
8
54mV
+
C4
–
–
C/10 STOP C/10
TIMER
+
DRV
CA
SLP
OSCILLATOR
BAT
–
SHDN
3
720Ω
LOGIC
LBO
COUNTER
6
1
C2
+
100µA
4.9V
VREF
–
+
–
VA
VCC
A1
–
+
+
C3
VREF
2.457V
2.5µA
CHARGE
5
BATTERY CURRENT IBAT = (2.457V • 800Ω)/(RPROG • RSENSE)
PROG
GND
4
1731 BD
RPROG
sn1731 17318fs
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LTC1731-8.2/LTC1731-8.4
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OPERATIO
The LTC1731-8.2/LTC1731-8.4 are linear battery charger
controllers. 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 that
creates a voltage drop from VCC 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 RSENSE which sets the charge current. When
the potential 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.
Charging 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 4.95V, the charger
goes into trickle charge mode. The trickle charge current
is 10% of the full-scale current. If the cell 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 4.95V.
In constant-current mode, the charge current is set by the
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
comparator will turn off the N-channel MOSFET at the
CHRG pin and connect a weak current source to ground to
indicate a near 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 impedance state. To restart the charge cycle, simply remove the
input voltage and reapply it, or float the PROG pin momentarily.
For batteries like lithium-ion that require an accurate final
float potential, the internal 2.457V reference, voltage
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 VCC. When in the
constant-current only mode, the voltage amplifier, timer
and the trickle charge function are all disabled.
The charger can be shut down by floating the PROG pin
(ICC ≈ 1mA). An internal current source will pull it high and
clamp at 3.5V.
When the input voltage is not present, the charger goes
into a sleep mode, dropping ICC to 15µA. This greatly
reduces the current drain on the battery and increases the
standby time.
sn1731 17318fs
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LTC1731-8.2/LTC1731-8.4
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APPLICATIONS INFORMATION
Charger Conditions
The charger is off when any of the following conditions
exist: the VCC pin is less than 8.2V, the droput voltage (VCC
- VBAT) is less than 54mV, the PROG pin is floating, or the
timer has ended. The DRV pin will be pulled to VCC and the
internal resistor divider 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 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
At the beginning of the charging sequence, if the battery
voltage is less than 4.95V the charger goes into trickle
charge mode. The charge current is reduced to 10% of the
full-scale current. If the low battery voltage persists for
one quarter of the total charging time, the battery is
considered defective, charging will be terminated and the
CHRG pin output is forced to a high impedance state.
Shutdown
The LTC1731-8.2/LTC1731-8.4 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 threshold voltage. The DRV pin is then pulled
up to VCC 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:
IBAT = (2.457V/RPROG)(800Ω/RSENSE)
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 is used to terminate the charge.
The length of the timer is programmed by an external
capacitor at the TIMER pin. The total charge time is:
Time (Hours) = (3 Hours)(CTIMER/0.1µF)
The timer starts when the 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 become high
impedance indicating that the charge cycle has ended.
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.
CHRG Status Output Pin
When the charge cycle starts, the CHRG pin is pulled to
ground by an internal N-channel MOSFET that can drive an
LED. When the charge current drops to 10% of the fullscale current (C/10), the N-channel MOSFET turns off and
a weak 100µA current source to ground is connected to the
CHRG pin. After a time-out occurs, the CHRG pin goes
high impedance indicating that the charge cycle has ended.
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.
V+
VDD
7
VCC
100k
LTC1731-8.4
CHRG
2
µPROCESSOR
2k
OUT
IN
1731 F01
where RPROG is the total resistance from the PROG pin to
ground.
Figure 1. Microprocessor Interface
For example, if 0.5A charge current is needed, select a
value for RSENSE that will drop 100mV at the maximum
charge current. RSENSE = 0.1V/0.5A = 0.2Ω, then calculate:
RPROG = (2.457V/500mA)(800Ω/0.2Ω) = 19.656k
sn1731 17318fs
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LTC1731-8.2/LTC1731-8.4
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APPLICATIONS INFORMATION
When the LTC1731 is in the charge mode, the CHRG pin
is pulled to ground 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 fullscale current (C/10), the N-channel MOSFET is turned off
and a 100µA current source is connected to the CHRG pin.
By forcing the OUT pin into a high impedance state, the
current source will pull the pin low through the 100k
resistor. When the internal timer has expired, the CHRG
pin will change to high impedance and the 100k resistor
will then pull the pin high to indicate the charge cycle has
ended.
End of Charge (C/10)
The LTC1731-8.2/LTC1731-8.4 include 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 and 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 100µA current
source to ground. After an internal time delay of 320ms,
this state is then latched. This delay will help prevent false
triggering due to transient currents. The end-of-charge
comparator is disabled in trickle charge mode.
Gate Drive
Typically the LTC1731-8.2/LTC1731-8.4 drive an external
P-channel MOSFET to supply current to the battery. The
DRV pin is internally clamped to 6.5V below VCC. This
feature allows low voltage P-channel MOSFETs with gate
to source breakdown voltage rated at 8V to be used.
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
charging current error. The gain of the current amplifier is
around 0.6µA/mV. For every 1µA of base current, a 1.6mV
gain error shows up at the inputs of CA. With RPROG =
19.6k and 100mV across RSENSE, this gain error causes a
1.67% error in charge current.
Constant-Current Only Mode
The LTC1731-8.2/LTC1731-8.4 can be used as a programmable current source by forcing the TIMER pin to
VCC. 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.
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. A ceramic output capacitor may also be
used, but because of the very low ESR and high Q
characteristics of multilayer ceramic capacitors, it may
be necessary to add a 1Ω resistor in series with the
ceramic capacitor to improve voltage mode stability.
When a PNP transistor is chosen as the pass transistor, a
1000pF 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.
sn1731 17318fs
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LTC1731-8.2/LTC1731-8.4
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PACKAGE DESCRIPTION
MS8 Package
8-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1660)
0.889 ± 0.127
(.035 ± .005)
5.23
(.206)
MIN
3.2 – 3.45
(.126 – .136)
0.42 ± 0.04
(.0165 ± .0015)
TYP
3.00 ± 0.102
(.118 ± .004)
(NOTE 3)
0.65
(.0256)
BSC
8
7 6 5
0.52
(.206)
REF
RECOMMENDED SOLDER PAD LAYOUT
0.254
(.010)
3.00 ± 0.102
(.118 ± .004)
NOTE 4
4.88 ± 0.1
(.192 ± .004)
DETAIL “A”
0° – 6° TYP
GAUGE PLANE
0.53 ± 0.015
(.021 ± .006)
DETAIL “A”
1
2 3
4
1.10
(.043)
MAX
0.86
(.34)
REF
0.18
(.077)
SEATING
PLANE
0.22 – 0.38
(.009 – .015)
0.65
(.0256)
BCS
0.13 ± 0.05
(.005 ± .002)
MSOP (MS8) 1001
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
sn1731 17318fs
10
LTC1731-8.2/LTC1731-8.4
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PACKAGE DESCRIPTION
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
0.189 – 0.197*
(4.801 – 5.004)
8
7
6
5
0.150 – 0.157**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
SO8 1298
1
0.010 – 0.020
× 45°
(0.254 – 0.508)
0.008 – 0.010
(0.203 – 0.254)
0.053 – 0.069
(1.346 – 1.752)
0°– 8° TYP
0.016 – 0.050
(0.406 – 1.270)
0.014 – 0.019
(0.355 – 0.483)
TYP
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
2
3
4
0.004 – 0.010
(0.101 – 0.254)
0.050
(1.270)
BSC
sn1731 17318fs
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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
11
LTC1731-8.2/LTC1731-8.4
U
TYPICAL APPLICATIO
Linear Charger Using a PNP Transistor
VIN = 9V
MBRM120T3
R2
2k
C1
1nF
7
CHARGE
STATUS
VCC
SENSE
2
DRV
CHRG
R1
10k
RSENSE
0.25Ω
Q2
ZTX749
8
6
Q1
2N5087
LTC1731-8.4
3
TIMER
CTIMER*
0.1µF
BAT
PROG
C3
1µF
IBAT = 400mA
1
5
GND
+
RPROG
19.6k
4
2-CELL
Li-ION
*AVX 0603ZC104KAT1A
C2
10µF
1731 TA02
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sn1731 17318fs
12
Linear Technology Corporation
LT/TP 0602 2K • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com
© LINEAR TECHNOLOGY CORPORATION 2000
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