LT1307CS8#PBF [Linear]
LT1307 - Single Cell Micropower 600kHz PWM DC/DC Converters; Package: SO; Pins: 8; Temperature Range: 0°C to 70°C;型号: | LT1307CS8#PBF |
厂家: | Linear |
描述: | LT1307 - Single Cell Micropower 600kHz PWM DC/DC Converters; Package: SO; Pins: 8; Temperature Range: 0°C to 70°C 转换器 |
文件: | 总20页 (文件大小:380K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LT1307/ LT1307B
Sing le Ce ll Mic ro p o we r
600kHz PWM DC/ DC Co nve rte rs
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DESCRIPTION
FEATURES
The LT®1307/LT1307B are micropower, fixed frequency
DC/DC converters that operate from an input voltage as
low as 1V. First in the industry to achieve true current
mode PWM performance from a single cell supply, the
LT1307 features automatic shifting to power saving Burst
Mode operation at light loads. High efficiency is main-
tained over a broad 100µA to 100mA load range. The
LT1307B does not shift into Burst Mode operation at light
loads, eliminating low frequency output ripple at the
expenseoflightloadefficiency. Thedevices containalow-
battery detector with a 200mV reference and shut down to
less than 5µA. No load quiescent current of the LT1307 is
50µAandtheinternalNPNpowerswitchhandles a500mA
current with a voltage drop of just 295mV.
■
Uses Small Ceramic Capacitors
50µA Quiescent Current (LT1307)
1mA Quiescent Current (LT1307B)
Operates with V as Low as 1V
■
■
■
IN
■
■
■
■
■
■
600kHz Fixed Frequency Operation
Starts into Full Load
Low Shutdown Current: 3µA
Low-Battery Detector
3.3V at 75mA from a Single Cell
Automatic Burst ModeTM Operation at
Light Load (LT1307)
■
■
Continuous Switching at Light Load (LT1307B)
Low VCESAT Switch: 295mV at 500mA
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Unlike competitive devices, large electrolytic capacitors
are not required with the LT1307/LT1307B in single cell
applications. The high frequency (600kHz) switching al-
lows the use of tiny surface mount multilayer ceramic
(MLC) capacitors along with small surface mount induc-
tors. The devices work with just 10µF of output capaci-
tance and require only 1µF of input bypassing.
APPLICATIONS
■
Pagers
Cordless Telephones
GPS Receivers
Battery Backup
Portable Electronic Equipment
Glucose Meters
Diagnostic Medical Instrumentation
■
■
■
■
■
The LT1307/LT1307B are available in 8-lead MSOP, PDIP
and SO packages.
■
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
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TYPICAL APPLICATION
Single Cell to 3.3V Converter Efficiency
L1
10µH
D1
90
C1: MURATA-ERIE GRM235Y5V105Z01
MARCON THCS50E1E105Z
V
SW
FB
IN
TOKIN 1E105ZY5U-C103-F
C2: MURATA-ERIE GRM235Y5V106Z01
C1
1µF
3.3V
75mA
80
LBI
V
IN
= 1.5V
V
MARCON THCS50E1E105Z
TOKIN 1E106ZY5U-C304-F
R1
1.02M
1%
LT1307
1.5V
CELL
SHUTDOWN SHDN
LBO
GND
= 1V
D1: MOTOROLA MBR0520L
L1: COILCRAFT D01608C-103
SUMIDA CD43-100
IN
V
C
C2
10µF
70
60
50
V
IN
= 1.25V
R2
604k
1%
100k
680pF
MURATA ERIE LQH3C100
FOR 5V OUTPUT: R1 = 1M, R2 = 329k
1307 F01
0.1
1
10
100
Figure 1. Single Cell to 3.3V Boost Converter
LOAD CURRENT (mA)
1307 TA01
1
LT1307/ LT1307B
W W W
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ABSOLUTE AXI U RATI GS
V , SHDN, LBO Voltage ......................................... 12V
SW Voltage ............................................................. 30V
Junction Temperature...........................................125°C
Operating Temperature Range
IN
FB Voltage ....................................................... V + 1V
Commercial (Note 1) ......................... –20°C to 70°C
Industrial ........................................... –40°C to 85°C
Storage Temperature Range ................ –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
IN
VC Voltage ................................................................ 2V
LBI Voltage ............................................ 0V ≤ VLBI ≤ 1V
Current into FB Pin .............................................. ±1mA
W
U
/O
PACKAGE RDER I FOR ATIO
ORDER PART
NUMBER
ORDER PART
NUMBER
TOP VIEW
V
1
2
3
4
8
7
6
5
LBO
LBI
LT1307CN8
LT1307CS8
LT1307IS8
LT1307BCS8
LT1307BIS8
TOP VIEW
C
LT1307CMS8
LT1307BCMS8
V
1
8 LBO
7 LBI
FB
SHDN
GND
C
FB 2
SHDN 3
GND 4
V
IN
6 V
IN
5 SW
SW
MS8 PACKAGE
8-LEAD PLASTIC MSOP
N8 PACKAGE
8-LEAD PDIP
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX = 125°C, θJA = 160°C/W
T
JMAX = 125°C, θJA = 100°C/W (N8)
MS8 PART MARKING
S8 PART MARKING
TJMAX = 125°C, θJA = 120°C/W (S8)
BU
BF
1307
1307B
1307I
1307BI
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
Commercial Grade 0°C to 70°C. V = 1.1V, VSHDN = V , TA = 25°C, LT1307/LT1307B unless otherwise noted.
IN
IN
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
I
Q
Quiescent Current
Not Switching (LT1307)
Not Switching (LT1307B)
●
●
●
50
1.0
1
90
1.5
3
µA
mA
µA
V
= 0V
SHDN
V
Feedback Voltage
●
●
1.20
1.22
27
1.24
60
V
FB
I
B
FB Pin Bias Current (Note 2)
Reference Line Regulation
V
= V
REF
nA
FB
1V ≤ V ≤ 2V (25°C, 0°C)
1V ≤ V ≤ 2V (70°C)
2V ≤ V ≤ 5V
0.6
1.1
1.5
0.8
%/V
%/V
%/V
IN
IN
●
0.3
IN
Minimum Input Voltage
Input Voltage Range
0.92
1
5
V
V
●
●
1
g
m
Error Amp Transconductance
Error Amp Voltage Gain
∆I = 5µA
25
35
65
µmhos
A
V
25°C, 0°C
70°C
35
30
100
V/V
V/V
f
Switching Frequency
●
550
600
750
kHz
OSC
2
LT1307/ LT1307B
ELECTRICAL CHARACTERISTICS
Commercial Grade 0°C to 70°C. V = 1.1V, VSHDN = V , TA = 25°C unless otherwise noted.
IN
IN
SYMBOL PARAMETER
Maximum Duty Cycle
CONDITIONS
MIN
TYP
MAX
UNITS
25°C, 0°C
70°C
80
76
84
%
%
Switch Current Limit (Note 3)
Switch V
DC = 40%
DC = 75%
●
0.6
0.5
1.25
A
A
I
SW
= 500mA (25°C, 0°C)
= 500mA (70°C)
295
350
400
mV
mV
CESAT
I
SW
Burst Mode Operation Switch Current Limit
(LT1307 Only)
L = 10µH
L = 22µH
100
50
mA
mA
Shutdown Pin Current
V
V
SHDN
= V
= 0V
●
●
2.5
–1.5
4.0
–2.5
µA
µA
SHDN
IN
LBI Threshold Voltage
LBO Output Low
●
●
●
●
190
200
0.1
210
0.25
0.1
mV
V
I
= 10µA
SINK
LBO Leakage Current
V
= 250mV, V = 5V
0.01
5
µA
nA
LBI
LBO
LBI Input Bias Current (Note 4)
Low-Battery Detector Gain
V
= 150mV
25
LBI
1MΩ Load (25°C, 0°C)
1MΩ Load (70°C)
1000
500
3000
V/V
V/V
Switch Leakage Current
Reverse Battery Current
V
= 5V
●
0.01
750
3
µA
SW
(Note 5)
mA
Commercial Grade TA = –20°C, V = 1.1V, VSHDN = V , unless otherwise noted (Note 1).
IN
IN
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
I
Q
Quiescent Current
V
= 1.3V, Not Switching (LT1307)
= 1.3V, Not Switching (LT1307B)
= 0V
50
1.1
1
100
1.6
3
µA
mA
µA
FB
V
FB
V
SHDN
V
Feedback Voltage
1.195
25
1.22
35
1.245
65
V
µmhos
V/V
FB
g
Error Amp Transconductance
Error Amp Voltage Gain
Switching Frequency
∆I = 5µA
m
A
V
35
100
600
84
f
500
80
750
350
kHz
OSC
Maximum Duty Cycle
%
Switch V
I
SW
= 500mA, V = 1.2V
250
mV
CESAT
IN
Shutdown Pin Current
V
V
SHDN
= V
= 0V
2.5
–1.5
4.0
–2.5
µA
µA
SHDN
IN
LBI Threshold Voltage
186
200
210
mV
3
LT1307/ LT1307B
ELECTRICAL CHARACTERISTICS
Industrial Grade –40°C to 85°C. V = 1.1V, VSHDN = V , LT1307/LT1307B unless otherwise noted.
IN
IN
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
I
Q
Quiescent Current
V
= 1.3V, Not Switching (LT1307)
= 1.3V, Not Switching (LT1307B)
= 0V
●
●
●
50
1
1
100
1.8
3
µA
mA
µA
FB
V
FB
V
SHDN
V
Feedback Voltage
●
●
1.195
10
1.22
27
1.245
100
V
FB
I
B
FB Pin Bias Current (Note 2)
Reference Line Regulation
V
= V
REF
nA
FB
1V ≤ V ≤ 2V (–40°C)
1V ≤ V ≤ 2V (85°C)
2V ≤ V ≤ 5V
0.6
1.1
3.2
0.8
%/V
%/V
%/V
IN
IN
●
0.3
IN
Minimum Input Voltage
–40°C
85°C
1.1
0.8
1.2
1.0
V
V
Input Voltage Range
●
●
5
V
g
Error Amp Transconductance
Error Amp Voltage Gain
∆I = 5µA
25
35
65
µmhos
m
A
V
–40°C
85°C
35
30
V/V
V/V
f
Switching Frequency
Maximum Duty Cycle
●
●
500
600
750
kHz
OSC
–40°C
85°C
80
75
84
80
%
%
Switch Current Limit (Note 3)
DC = 40%
DC = 75%
0.6
0.5
1.25
A
A
Switch V
I
= 500mA, V = 1.2V (–40°C)
= 500mA (85°C)
250
330
350
400
mV
mV
CESAT
SW
IN
I
SW
Burst Mode Operation Switch Current Limit
(LT1307 Only)
L = 10µH
L = 22µH
100
50
mA
mA
Shutdown Pin Current
V
V
SHDN
= V
= 0V
●
●
2.5
–1.5
4.0
–2.5
µA
µA
SHDN
IN
LBI Threshold Voltage
LBO Output Low
●
●
●
●
186
200
0.1
0.1
5
210
0.25
0.3
mV
V
I
= 10µA
SINK
LBO Leakage Current
V
= 250mV, V = 5V
µA
nA
LBI
LBO
LBI Input Bias Current (Note 4)
Low-Battery Detector Gain
V
= 150mV
30
LBI
1MΩ Load (–40°C)
1MΩ Load (85°C)
1000
400
6000
V/V
V/V
Switch Leakage Current
V
SW
= 5V
●
0.01
3
µA
The
●
denotes specifications which apply over the full operating
Note 2: Bias current flows into FB pin.
temperature range.
Note 3: Switch current limit guaranteed by design and/or correlation to
Note 1: Specifications for commercial (C) grade devices are guaranteed
but not tested at –20°C. MS8 package devices are designed for and
intended to meet commercial temperature range specifications but are not
static tests. Duty cycle affects current limit due to ramp generator.
Note 4: Bias current flows out of LBI pin.
Note 5: The LT1307 will withstand continuous application of 1.6V applied
tested at – 20°C or 0°C.
to the GND pin while V and SW are grounded.
IN
4
LT1307/ LT1307B
W
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TYPICAL PERFORMANCE CHARACTERISTICS
3.3V Output Efficiency, Circuit of
Figure 1 (LT1307B)
5V Output Efficiency, Circuit of
Figure 1 (LT1307B)
5V Output Efficiency, Circuit of
Figure 1 (LT1307)
90
80
70
60
50
90
80
70
60
50
40
30
20
10
90
80
70
60
50
40
30
20
10
V
IN
= 1.5V
V
IN
= 1V
V
IN
= 1.25V
V
IN
= 1.25V
V
IN
= 1V
V
IN
= 1.00V
V
IN
= 1.25V
V
IN
= 1.5V
V
IN
= 1.5V
10
1
LOAD CURRENT (mA)
100
200
0.1
0.1
1
10
100
0.1
1
10
100
LOAD CURRENT (mA)
LOAD CURRENT (mA)
LT1307 • G01
1307 G02
LT1307 • TPC03
Feedback Bias Current vs
Temperature
LBI Bias Current vs Temperature
Quiescent Current vs Temperature
50
40
30
20
80
16
14
12
10
8
V
IN
= 1.1V
70
60
50
40
30
20
10
0
6
4
10
0
2
0
–25
0
50
–50
0
25
50
75
100
–25
0
50
–50
75
100
–50
75
100
25
–25
25
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
LT1307 • TPC04
LTC1307 • TPC05
LT1307 • TPC06
Shutdown Pin Bias Current vs
Input Voltage
Switch VCESAT vs Current
Quiescent Current in Shutdown
10
8
10
16
12
8
500
400
300
200
T
= 25°C
A
6
4
2
4
100
0
0
0
0
1
2
3
4
5
0
1
2
3
4
5
0
200
300
400
500
600
100
SWITCH CURRENT (mA)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
LT1307 • TPC07
LT1307 • TPC08
LT1307 • TPC09
5
LT1307/ LT1307B
W
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TYPICAL PERFORMANCE CHARACTERISTICS
Oscillator Frequency vs
Input Voltage
Feedback Voltage vs
Temperature
LBI Reference vs Temperature
1.230
1.225
1.220
1.215
1.210
1.205
1.200
900
800
700
600
500
400
210
208
206
204
202
200
198
196
194
192
190
25°C
85°C
–40°C
–50
0
25
50
75
100
–25
3
1
2
4
5
–50
–25
25
50
75
100
0
TEMPERATURE (°C)
TEMPERATURE (°C)
INPUT VOLTAGE (V)
LT1307 • TPC10
LT1307 • TPC12
LT1307 • TPC11
Transient Response (LT1307)
Transient Response (LT1307B)
Load Regulation (LT1307)
VOUT
200mV/DIV
AC COUPLED
V
OUT
200mV/DIV
AC COUPLED
VOUT
50mV/DIV
DC
COUPLED
OFFSET
ADDED
IL
IL
200mA/DIV
200mA/DIV
55mA
ILOAD
55mA
ILOAD
5mA
5mA
V
IN = 1.25V
500µs/DIV
1307 G13
V
IN = 1.25V
500µs/DIV
1307 G14
V
IN = 0.92V
ILOAD 10mA/DIV
1307 G15
VOUT = 3.3V
VOUT = 3.3V
VOUT = 3.3V
Load Regulation (LT1307)
Load Regulation (LT1307)
Load Regulation (LT1307)
V
OUT
V
OUT
V
OUT
50mV/DIV
50mV/DIV
DC
50mV/DIV
DC
DC
COUPLED
OFFSET
ADDED
COUPLED
OFFSET
ADDED
COUPLED
OFFSET
ADDED
VIN = 1.15V
ILOAD 20mA/DIV
1307 G17
VIN = 1V
ILOAD 10mA/DIV
1307 G18
VIN = 1V
ILOAD 20mA/DIV
1307 G16
VOUT = 3.3V
VOUT = 5V
VOUT = 3.3V
Circuit Operation, L = 10µH
(LT1307)
Circuit Operation, L = 22µH
(LT1307)
Load Regulation (LT1307)
VOUT
50mV/DIV
AC COUPLED
VOUT
50mV/DIV
AC COUPLED
V
OUT
50mV/DIV
DC
COUPLED
OFFSET
ADDED
V
SW
V
5V/DIV
SW
5V/DIV
IL
IL
100mA/DIV
100mA/DIV
V
IN = 1.25V
VOUT = 5V
LOAD = 1.5mA
100µs/DIV
1307 G20
V
IN = 1.25V
VOUT = 5V
ILOAD = 1.5mA
100µs/DIV
1307 G21
V
IN = 1.15V
ILOAD 10mA/DIV
1307 G19
VOUT = 5V
I
6
LT1307/ LT1307B
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PIN FUNCTIONS
V (Pin 1): Compensation Pin for Error Amplifier. Con-
C
SW (Pin 5): Switch Pin. Connect inductor/diode here.
nect a series RC from this pin to ground. Typical values
Minimize trace area at this pin to keep EMI down.
are 100kΩ and 680pF. Minimize trace area at V .
C
V (Pin 6): Supply Pin. Must have 1µF ceramic bypass
IN
FB (Pin 2): Feedback Pin. Reference voltage is 1.22V.
Connect resistor divider tap here. Minimize trace area at
FB. Set VOUT according to: VOUT = 1.22V(1 + R1/R2).
capacitor right at the pin, connected directly to ground.
LBI (Pin 7): Low-Battery Detector Input. 200mV refer-
ence. Voltage on LBI must stay between ground and
SHDN (Pin 3): Shutdown. Ground this pin to turn off 700mV.
switcher. MustbetiedtoV (orhighervoltage)toenable
switcher. Do not float the SHDN pin.
IN
LBO (Pin 8): Low-Battery Detector Output. Open collec-
tor, can sink 10µA. A 1MΩ pull-up is recommended.
GND (Pin 4): Ground. Connect directly to local ground
plane.
W
BLOCK DIAGRAM
V
IN
6
V
IN
R5
R6
40k
40k
SHDN
+
–
V
C
SHUTDOWN
3
g
1
m
V
OUT
LBI
7
R1
ERROR
AMPLIFIER
+
–
+
–
(EXTERNAL)
FB
2
LBO
8
Q1
Q2
×10
*
FB
ENABLE
200mV
R2
BIAS
R3
30k
A4
A1
(EXTERNAL)
R4
140k
SW
5
COMPARATOR
–
DRIVER
FF
RAMP
GENERATOR
Q3
R
Q
+
Σ
+
+
S
A2
+
A = 3
–
0.15Ω
600kHz
OSCILLATOR
4
GND
1307 F02
*HYSTERESIS IN LT1307 ONLY
Figure 2. LT1307/LT1307B Block Diagram
7
LT1307/ LT1307B
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APPLICATIONS INFORMATION
OPERATION
200mV. There is no hysteresis in A4, allowing it to be used
as an amplifier in some applications. The entire device is
disabled when the SHDN pin is brought low. To enable the
The LT1307 combines a current mode, fixed frequency
PWMarchitecturewithBurstModemicropoweroperation
to maintain high efficiency at light loads. Operation can
best be understood by referring to the block diagram in
Figure 2. Q1 and Q2 form a bandgap reference core whose
loop is closed around the output of the converter. When
converter, SHDN must be at V or at a higher voltage.
IN
The LT1307B differs from the LT1307 in that there is no
hysteresis in comparator A1. Also, the bias point on A1 is
set lower than on the LT1307 so that switching can occur
at inductor current less than 100mA. Because A1 has no
hysteresis, there is no Burst Mode operation at light loads
and the device continues switching at constant frequency.
This results intheabsenceoflowfrequencyoutputvoltage
ripple at the expense of efficiency.
V is 1V, the feedback voltage of 1.22V, along with an
IN
80mV drop across R5 and R6, forward biases Q1 and Q2’s
base collector junctions to 300mV. Because this is not
enough to saturate either transistor, FB can be at a higher
voltage than V . When there is no load, FB rises slightly
IN
above 1.22V, causing V (the error amplifier’s output) to
C
The difference between the two devices is clearly illus-
trated in Figures 3 and 4. The top two traces in Figure 3
show an LT1307/LT1307B circuit, using the components
indicated in Figure 1, set to a 5V output. Input voltage is
1.25V.Loadcurrentis steppedfrom1mAto41mAforboth
circuits. Low frequency Burst Mode operation voltage
ripple is observed on Trace A, while none is observed on
decrease. When V reaches the bias voltage on hysteretic
C
comparator A1, A1’s output goes low, turning off all
circuitry except the input stage, error amplifier and low-
battery detector. Total current consumption in this state is
50µA. As output loading causes the FB voltage to de-
crease, A1’s output goes high, enabling the rest of the IC.
Switch current is limited to approximately 100mA initially
after A1’s output goes high. If the load is light, the output
voltage (and FB voltage) will increase until A1’s output
goes low, turning off the rest of the LT1307. Low fre-
quency ripple voltage appears at the output. The ripple
frequencyis dependentonloadcurrentandoutputcapaci-
tance. This Burst Mode operation keeps the output regu-
lated and reduces average current into the IC, resulting in
high efficiency even at load currents of 100µA or less.
LT1307
V
OUT
TRACE A
500mV/DIV
AC COUPLED
LT1307B
V
OUT
TRACE B
500mV/DIV
AC COUPLED
41mA
IL
1mA
VIN = 1.25V
1ms/DIV
1307 F03
V
OUT = 5V
If the output load increases sufficiently, A1’s output re-
mains high, resulting in continuous operation. When the
LT1307 is running continuously, peak switch current is
Figure 3. LT1307 Exhibits Burst Mode Operation Ripple at
1mA Load, LT1307B Does Not
controlled by V to regulate the output voltage. The switch
C
is turned on at the beginning of each switch cycle. When
thesummationofasignalrepresentingswitchcurrentand
a ramp generator (introduced to avoid subharmonic oscil-
LT1307
V
OUT
TRACE A
200mV/DIV
AC COUPLED
lations at duty factors greater than 50%) exceeds the V
C
LT1307B
V
OUT
signal, comparator A2 changes state, resetting the flip-
flopandturningofftheswitch.Outputvoltageincreases as
switch current is increased. The output, attenuated by a
resistor divider, appears at the FB pin, closing the overall
loop. Frequency compensation is provided by an external
TRACE B
200mV/DIV
AC COUPLED
45mA
IL
5mA
VIN = 1.5V
500µs/DIV
1307 F04
VOUT = 5V
Figure 4. At Higher Loading and a 1.5V Supply, LT1307
Again Exhibits Burst Mode Operation Ripple at 5mA Load,
LT1307B Does Not
series RC network connected between the V pin and
ground. Low-battery detector A4’s open collector output
(LBO) pulls low when the LBI pin voltage drops below
C
8
LT1307/ LT1307B
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APPLICATIONS INFORMATION
Trace B. Similarly, Figure 4 details the two circuits with a
load step from 5mA to 45mA with a 1.5V input.
quite evident, as is this particular device’s 575kHz switch-
ing frequency (nominal switching frequency is 600kHz).
Note,however,theabsenceofsignificantenergyat455kHz.
Figure7’s plotreduces thefrequencyspanfrom255kHzto
655kHz with a 455kHz center. Burst Mode low frequency
ripple creates sidebands around the 575kHz switching
fundamental. These sidebands have low signal amplitude
at 455kHz, measuring –55dBmVRMS. As load current is
further reduced, the Burst Mode frequency decreases.
This spaces the sidebands around the switching fre-
quency closer together, moving spectral energy further
The LT1307B also can be used in lower current applica-
tions where a clean, low ripple output is needed. Figure 5
details transient response of a single cell to 3.3V con-
verter, using an inductor value of 100µH. This high induc-
tance minimizes ripple current, allowing the LT1307B to
regulate without skipping cycles. As the load current is
stepped from 5mA to 10mA, the output voltage responds
cleanly. Note that the V pin loop compensation has been
C
made more conservative (increased C, decreased R).
40
RBW = 100Hz
30
V
OUT
100mV/DIV
AC COUPLED
20
10
0
IL
–10
–20
–30
–40
–50
–60
20mA/DIV
10mA
IL
5mA
V
IN = 1.25V
1ms/DIV
1307 F05
VOUT = 3.3V
Figure 5. Increasing L to 100µH, Along with RC = 36k,
CC = 20nF and COUT = 10µF, Low Noise Performance of
LT1307B Can Be Realized at Light Loads of 5mA to 10mA
1
10
100
1000
FREQUENCY (kHz)
1307 F06
Figure 6. Spectral Noise Plot of 3.3V Converter Delivering
5mA Load. Burst Mode Fundamental at 5.1kHz is 23dBmV
At light loads, the LT1307B will begin to skip alternate
cycles. The load point at which this occurs can be de-
creasedbyincreasingtheinductorvalue. However, output
ripplewillcontinuetobesignificantlyless thantheLT1307
output ripple. Further, the LT1307B can be forced into
micropower mode, where IQ falls from 1mA to 50µA by
RMS
or 14mV
RMS
–20
–25
–30
–35
–40
–45
–50
–55
–60
–65
–70
RBW = 100Hz
pulling down V to 0.3V or less externally.
C
DC/DC CONVERTER NOISE CONSIDERATIONS
Switching regulator noise is a significant concern in many
communications systems. The LT1307 is designed to
keep noise energy out of the sensitive 455kHz band at all
load levels while consuming only 60µW to 100µW at no
load. At light load levels, the device is in Burst Mode,
causing low frequency ripple to appear at the output.
Figure 6 details spectral noise directly at the output of
Figure 1’s circuit in a 1kHz to 1MHz bandwidth. The
converter supplies a 5mA load from a 1.25V input. The
Burst Mode fundamental at 5.1kHz and its harmonics are
255
455
FREQUENCY (kHz)
655
1307 F07
Figure 7. Span Centered at 455kHz Shows –55dBmV
RMS
(1.8µVRMS) at 455kHz. Burst Mode Creates Sidebands 5.1kHz
Apart Around the Switching Frequency Fundamental of 575kHz
9
LT1307/ LT1307B
U
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APPLICATIONS INFORMATION
away from 455kHz. Figure 8 shows the noise spectrum of To eliminate the low frequency noise of Figure 6, the
the converter with the load increased to 20mA. The
LT1307 can be replaced with the LT1307B. Figure 9
LT1307 shifts out of Burst Mode operation, eliminating details thespectralnoiseattheoutputofFigure1’s circuit
low frequency ripple. Spectral energy is present only at
the switching fundamental and its harmonics. Noise
usinganLT1307Bat5mAload. Althoughspectralenergy
is present at 333kHz due to alternate pulse skipping, all
Burst Mode operation spectral components are gone.
Alternate pulse skipping can be eliminated by increasing
voltage measures –5dBmV
or 560µV
at the
RMS
RMS
575kHzswitchingfrequency,andis below–60dBmV
RMS
for all other frequencies in the range. By combining Burst inductance.
Mode with fixed frequency operation, the LT1307 keeps
noise away from 455kHz.
FREQUENCY COMPENSATION
Obtaining proper values for the frequency compensation
network is largely an empirical, iterative procedure, since
variations in input and output voltage, topology, capacitor
value and ESR, and inductance make a simple formula
elusive. As an example, consider the case of a 1.25V to
3.3V boost converter supplying 50mA. To determine
optimum compensation, the circuit is built and a transient
load is applied to the circuit. Figure 10 shows the setup.
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
RBW = 100Hz
MBR0520L
10µH
V
OUT
255
455
FREQUENCY (kHz)
655
V
SW
FB
IN
66Ω
1M
1307 F08
SHDN
LT1307
1µF
Figure 8. With Converter Delivering 20mA, Low Frequency
Sidebands Disappear. Noise is Present Only at the 575kHz
Switching Frequency
V
C
3300Ω
10µF*
1.25V
GND
R
590k
C
50Ω
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
1307 • F10
*CERAMIC
Figure 10. Boost Converter with Simulated Load
Figure 11a details transient response without compensa-
tion components. Although the output ripple voltage at a
1mA load is low, allowing the error amplifier to operate
widebandresults inexcessiverippleata50mAload. Some
kind of loop stabilizing network is obviously required. A
100k/22nF series RC is connected to the VC pin, resulting
in the response pictured in Figure 11b. The output settles
in about 7ms to 8ms. This may be acceptable, but we can
do better. Reducing C to 2nF gives Figure 11c’s response.
This is clearly in the right direction. After another order of
magnitude reduction, Figure 11d’s response shows some
205
455
705
FREQUENCY (kHz)
LT1307 • F09
Figure 9. LT1307B at 5mA Load Shows No Audio Components
or Sidebands About Switching Frequency, 333kHz
Fundamental Amplitude is –10dBmV, or 316µV
RMS
10
LT1307/ LT1307B
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APPLICATIONS INFORMATION
V
OUT
V
OUT
200mV/DIV
AC COUPLED
200mV/DIV
AC COUPLED
51mA
IL
51mA
IL
1mA
1mA
5ms/DIV
1307 F11a
5ms/DIV
1307 F11b
Figure 11a. V Pin Left Unconnected. Output Ripple
Voltage is 300mVP-P Under Load
Figure 11b. Inclusion of a 100k/22nF Series RC on VC
Pin Results in Overdamped Stable Response
C
V
OUT
V
OUT
200mV/DIV
AC COUPLED
200mV/DIV
AC COUPLED
51mA
IL
51mA
IL
1mA
1mA
1ms/DIV
1307 F11a
500µs/DIV
1307 F11b
Figure 11c. Reducing C to 2nF Speeds Up Response,
Although Still Overdamped
Figure 11d. A 100k/200pF Series RC Shows Some
Underdamping
VOUT
200mV/DIV
AC COUPLED
51mA
IL
1mA
1ms/DIV
1307 F11b
Figure 11e. A 100k/680pF RC Provides Optimum
Settling Time with No Ringing
underdamping.Nowsettlingtimeis about300µs.Increas-
pole, requiring added C at the VC pin network to prevent
ingCto680pFresults intheresponseshowninFigure11e.
This response has minimum settling time with no over-
shoot or underdamping.
loop oscillation.
Observant readers will notice R has been set to 100k for all
the photos in Figure 11. Usable R values can be found in
the 10k to 500k range, but after too many trips to the
resistor bins, 100k wins.
Converters using a 2-cell input need more capacitance at
the output. This added capacitance moves in the output
11
LT1307/ LT1307B
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APPLICATIONS INFORMATION
COMPONENT SELECTION
Inductors
LAYOUT HINTS
The LT1307 switches current at high speed, mandating
carefulattentiontolayoutforproperperformance.Youwill
not get advertised performance with careless layouts.
Figure 12 shows recommended component placement.
Follow this closely in your PC layout. Note the direct path
of the switching loops. Input capacitor C must be placed
close (<5mm) to the IC package. As little as 10mm of wire
or PC trace from C to V will cause problems such as
inability to regulate or oscillation. A 1µF ceramic bypass
capacitor is the only input capacitance required provided
the battery has a low inductance path to the circuit. The
battery itself provides the bulk capacitance the device
requires forproperoperation.Ifthebatteryis locatedsome
distancefromthecircuit, anadditionalinputcapacitormay
berequired. A100µFaluminumelectrolyticunitworks well
in these cases. This capacitor need not have low ESR.
Inductors appropriate for use with the LT1307 must pos-
sess three attributes. First, they must have low core loss at
600kHz. Most ferrite core units have acceptable losses at
this switching frequency. Inexpensive iron powder cores
should be viewed suspiciously, as core losses can cause
significant efficiency penalties at 600kHz. Second, the
inductor must handle current of 500mA without saturat-
ing.This places alowerlimitonthephysicalsizeoftheunit.
Molded chokes or chip inductors usually do not have
enough core to support 500mA current and are unsuitable
for the application. Lastly, the inductor should have low
DCR (copper wire resistance) to prevent efficiency-killing
I2Rlosses.LinearTechnologyhas identifiedseveralinduc-
tors suitable for use with the LT1307. This is not an
exclusive list. There are many magnetics vendors whose
components are suitable for use. A few vendor’s compo-
nents are listed in Table 1.
IN
IN
IN
C
C
R
C
KEEP TRACES
OR LEADS SHORT!
LT1307
1
2
3
4
8
7
6
5
Table 1. Inductors Suitable for Use with the LT1307
MAX
HEIGHT
(mm)
R1 R2
PART
VALUE DCR
MFR
COMMENT
L
C
IN
LQH3C100
DO1608-103
CD43-100
CD54-100
10µH
10µH
10µH
10µH
0.57 Murata-Erie
2.0
3.0
3.2
4.5
2.2
Smallest Size
0.16
0.18
0.10
Coilcraft
Sumida
Sumida
D
C
OUT
Best Efficiency
1210 Footprint
1306 F12
CTX32CT-100 10µH
0.50 Coiltronics
V
OUT
GROUND
Figure 12. Recommended Component Placement. Traces
Carrying High Current Are Direct. Trace Area at FB Pin and V
Capacitors
C
Pin is Kept Low. Lead Length to Battery Should Be Kept Short
For single cell applications, a 10µF ceramic output capaci-
tor is generally all that is required. Ripple voltage in Burst
Mode can be reduced by increasing output capacitance.
For 2- and 3-cell applications, more than 10µF is needed.
For a typical 2-cell to 5V application, a 47µF to 100µF low
ESRtantalumcapacitorworks well.AVXTPSseries (100%
surgetested)orSprague(don’tbevague—askforSprague)
594Dseries arebothgoodchoices forlowESRcapacitors.
Alternatively, a 10µF ceramic in parallel with a low cost
(read high ESR) electrolytic capacitor, either tantalum or
aluminum, can be used instead. For through hole applica-
OPERATION FROM A LABORATORY POWER SUPPLY
If a lab supply is used, the leads used to connect the circuit
to the supply can have significant inductance at the
LT1307’s switching frequency. As in the previous situa-
tion, anelectrolyticcapacitormayberequiredatthecircuit
in order to reduce the AC impedance of the input suffi-
ciently. An alternative solution would be to attach the
circuitdirectlytothepowersupplyatthesupplyterminals,
without the use of leads. The power supply’s output
capacitance will then provide the bulk capacitance the
LT1307 circuit requires.
12
LT1307/ LT1307B
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APPLICATIONS INFORMATION
V
tions wheresmallsizeis notcritical, PanasonicHFQseries
aluminum electrolytic capacitors have been found to per-
form well.
IN
Q3
R2
400k
SHUTDOWN
CURRENT
SHDN
Table 2. Vendor Telephone Numbers
200k
VENDOR
Coilcraft
Marcon
Murata-Erie
Sumida
Tokin
COMPONENTS
Inductors
TELEPHONE
(708) 639-6400
(708) 913-9980
(404) 436-1300
(847) 956-0666
(408) 432-8020
(207) 282-5111
(603) 224-1961
(407) 241-7876
START-UP
CURRENT
Capacitors
Q2
Q1
Inductors, Capacitors
Inductors
1307 F13
Capacitors
Figure 13. Shutdown Circuit
AVX
Capacitors
Sprague
Coiltronics
Capacitors
LOW-BATTERY DETECTOR
Inductors
The LT1307’s low-battery detector is a simple PNP input
gain stage with an open collector NPN output. The nega-
tive input of the gain stage is tied internally to a 200mV
±5% reference. The positive input is the LBI pin. Arrange-
ment as a low-battery detector is straightforward. Figure
14 details hookup. R1 and R2 need only be low enough in
value so that the bias current of the LBI pin doesn’t cause
large errors. For R2, 100k is adequate. The 200mV refer-
ence can also be accessed as shown in Figure 15.
Diodes
Most of the application circuits on this data sheet specify
the Motorola MBR0520L surface mount Schottky diode.
This 0.5A, low drop diode complements the LT1307 quite
well. In lower current applications, a 1N4148 can be used,
although efficiency will suffer due to the higher forward
drop. This effect is particularly noticeable at low output
voltages. For higher voltage output applications, such as
LCD bias generators, the extra drop is a small percentage
of the output voltage so the efficiency penalty is small. The
low cost of the 1N4148 makes it attractive wherever it can
be used. In through hole applications the 1N5818 is the all
around best choice.
3.3V
R1
V
IN
LT1307
LBO
1M
LBI
+
–
TO PROCESSOR
R2
100k
200mV
INTERNAL
REFERENCE
V
LB
– 200mV
R1 =
SHUTDOWN PIN
2µA
GND
The LT1307 has a Shutdown pin (SHDN) that must be
groundedtoshutthedevicedownortiedtoavoltageequal
1307 F14
or greater than V to operate. The shutdown circuit is
shown in Figure 13.
IN
Figure 14. Setting Low-Battery Detector Trip Point
Note that allowing SHDN to float turns on both the start-
up current (Q2) and the shutdown current (Q3) for V >
200k
IN
V
IN
2V .TheLT1307doesn’tknowwhattodointhis situation
2N3906
LBO
LBI
BE
LT1307
and behaves erratically. SHDN voltage above V is al-
IN
V
REF
200mV
+
lowed. This merely reverse-biases Q3’s base emitter junc-
tion, a benign condition.
GND
10k
10µF
1307 F15
Figure 15. Accessing 200mV Reference
13
LT1307/ LT1307B
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APPLICATIONS INFORMATION
REVERSE BATTERY CONSIDERATIONS
tion after sustaining polarity reversal for the life of a single
AA alkaline cell.
The LT1307 is built ona junction-isolatedbipolar process.
The p-type substrate is connected to the GND pin of the
LT1307. Substrate diodes, normally reverse-biased, are
When using a 2- or 3-cell supply, an external protection
diode is recommended as shown in Figure 18. When the
batterypolarityis reversed, the1N4001conducts, limiting
reverse voltage across the LT1307 to a single diode drop.
This arrangementwillquicklydepletethecells’energy,but
it does prevent the LT1307 from excessive power dissipa-
tion and potential damage.
present on the SW pin and the V pin as shown in Figure
IN
16. When the battery polarity is reversed, these diodes
conduct, as illustrated in Figure 17. With a single AA or
AAA cell, several hundred milliamperes flow in the circuit.
TheLT1307canwithstandthis currentwithoutdamage.In
laboratory tests, the LT1307 performed without degrada-
–1.5V
CURRENT
FLOW
1.5V
V
IN
SW
V
IN
SW
1 CELL
D1
D2
Q1
1 CELL
D1
D2
Q1
LT1307
GND
LT1307
GND
1307 F17
1307 F16
Figure 17. When Cell Is Reversed Current Flows through
D1 and D2
Figure 16. LT1307 Showing Internal Substrate Diodes D1 and D2.
In Normal Operation Diodes are Reverse-Biased
V
IN
SW
2 OR 3
1N4001
CELLS
LT1307
GND
1307 F18
Figure 18. 1N4001 Diode Protects LT1307 from Excessive Power
Dissipation When a 2- or 3-Cell Battery is Used
14
LT1307/ LT1307B
U
TYPICAL APPLICATIONS N
Externally Controlled Burst Mode Operation
L1
10µH
MBR0520
V
OUT
1µF
CERAMIC
R4
1M
300k
V
SW
IN
V
C
FB
100k
R5
590k
2
LT1307B
R3
698k
CELLS
V
3.3V
OUT
M1
LBO
LBI
2N7002
200mA
SHDN
GND
C2*
10µF
CERAMIC
3.0V IN LOW-POWER
Burst Mode OPERATION
C1 = AVX TPSC107K006R0150
L1 = COILCRAFT DO1608-103
SUMIDA CD43-100
1nF
+
R2
499k
C1
R1
100µF
10M
* C2 OPTIONAL: REDUCES OUTPUT
RIPPLE CAUSED BY C1'S ESR
GROUND = HIGH POWER/LOW NOISE
FLOAT = Burst Mode OPERATION
1307 F19
SHUTDOWN
detector now drives the V pin. R3 and R2 set the output
This circuit overcomes the limitation of load-based
transitioning between Burst Mode operation and constant
switching mode by adding external control. If M1’s gate is
grounded by an external open-drain signal, the converter
functions normallyinconstantswitchingmode,delivering
3.3V. Output noise is low, however efficiency at loads less
than 1mA is poor due to the 1mA supply current of the
LT1307B. If M1’s gate is allowed to float, the low-battery
C
to 3V by allowing M1’s gate to go to VOUT until the output
voltage drops below 3V. R1 adds hysteresis, resulting in
low-frequency Burst Mode operation ripple voltage at the
output. By pulling the VC pin below a V , quiescent
BE
currentoftheLT1307Bdrops to60µA, resultinginaccept-
able efficiency at loads in the 100µA range.
V
OUT
V
OUT
500mV/DIV
100mV/DIV
100mA
IL
10mA
IL
100µA
10mA
0.2s/DIV
1307 F20
2ms/DIV
1307 F21
This photo details output voltage as the circuit is switched
between the two modes. Load current is 100µA in Burst
Mode operation; 10mA in constant switching mode.
This photo shows transient response in constant switch-
ing mode with a 10mA to 100mA stepped load. Output
ripple at the switching frequency can be reduced consid-
erably by adding a 10µF ceramic capacitor in parallel with
the 100µF tantalum.
15
LT1307/ LT1307B
TYPICAL APPLICATIONS N
U
Low Cost 2-Cell to 5V
L1
V
IN
1N5818
10µH
1.4V TO 3.3V
5V
100mA
C1*
220µF
6.3V
C2
220µF
6.3V
+
+
V
SW
FB
IN
LT1307
SHDN
1M
0.1µF
0.1µF
GND
100k
4700pF
323k
1307 TA02
C1, C2: PANASONIC ECA0JFQ221
(DIGI-KEY P5604-ND)
L1: SUMIDA CD43-100
Step-Up/Step-Down Converter
2.2µF
CERAMIC
L1
10µH
V
IN
MBR0520
2.1V TO 4.8V
•
3.3V
100mA
V
IN
SW
10µF
1µF
CERAMIC
CERAMIC
LT1307
1.02M
608k
•
3
CELLS
V
FB
GND
C
L1*
SHDN
100k
1000pF
SHDN
1307 TA03
L1: COILTRONICS CTX10-1 OR 2 MURATA ERIE LQH3C100
EFFICIENCY ≈70% TO 73%
Constant Current NiCd Battery Charger with Overvoltage Protection
for Acknowledge-Back Pagers
2.2µF
CERAMIC
L1
10µH
V
IN
MBR0520L
15mA
1.8V TO 1V
3
2
•
1µF
V
SW
FB
IN
1M
•
1
V
C
1µF
CERAMIC
OVERVOLTAGE
PROTECTION
323k
1 CELL
AA OR
AAA
3 CELLS
NiCd
LT1307
4
30k
200mV
1nF
–100mV
LBO
LBI
SHDN
GND
47k
2200pF
280k
6.7Ω
1 = CHARGE
0 = SHUTDOWN
3V
1307 TA04
L1: COILTRONICS CTX10-1
16
LT1307/ LT1307B
U
TYPICAL APPLICATIONS N
Single Cell Powered Constant Current LED Driver
L1
D1
10µH
V
IN
100k
D2
V
SW
FB
IN
Q1
2N3906
LBO
NC
LT1307B
C1
1µF
CERAMIC
AA
CELL
V
C
LBI
SHDN
GND
+
C2
1µF
40mA
C3
22µF
CERAMIC
R2
22k
R1
5.1Ω
100k
1307 TA05
ON/OFF
L1: MURATA-ERIE LQH3C100K04
D1: 1N4148
C1, C2: CERAMIC
V
IN
D2, D3: LUMEX SSL-X100133SRC/4 "MEGA-BRITE" RED LED
OR PANASONIC LNG992CF9 HIGH BRIGHTNESS BLUE LED
Flash Memory VPP Supply
L1
10µH
D1
12V/30mA FROM 3V
12V/60mA FROM 5V
V
IN
3V TO 5.5V
+
~250mV RIPPLE
0.33µF
1µF
P-P
TANTALUM
10pF
V
SW
FB
IN
SHUTDOWN
SHDN
LT1307
0.33µF
CERAMIC
×2
2M
1%
1N4148
47k
V
C
GND
232k
1%
2000pF
D1: MOTOROLA MBR0520L
L1: MURATA-ERIE LQH3C100K04
1307 TA09
High Voltage Flyback Converter
OPTIONAL
DOUBLER
2V
OUT
0.01µF
0.1µF
T1
1:12
1N4148
V
IN
T1: DALE LPE3325-A190, n = 12 (605) 665-9301
R1
1V TO 5V
•
1µF
CERAMIC
3
1
4
6
V
OUT
= 1.22V 1 +
(
)
R2
MAXIMUM DUTY CYCLE: ≈80%
•
DC
1 – DC
FOR FLYBACK, V
=
n(V – V
)
SW
OUT
IN
V
SW
FB
IN
R1
0.8
FOR 1V , MAXIMUM V
=
OUT
12(1 – 0.2) ≈ 37V
IN
SHUTDOWN
SHDN
LT1307
V
OUT
1 – 0.8
≈ 85V.
OUT
FOR 2V , MAXIMUM V
IN
HIGHER VOLTAGES ACHIEVED WITH CAPACITIVE DOUBLER OR TRIPLER
V
C
R2
240k
1%
NO SNUBBER REQUIRED WITH SPECIFIED TRANSFORMER AND V < 5V
IN
GND
0.1µF
100k
1000pF
1307 TA06
17
LT1307/ LT1307B
TYPICAL APPLICATIONS N
U
Single Cell CCFL Power Supply
6
3
10
1
47pF
3kV
T1
4
5
2
1.5V
100Ω
C1
0.1µF
CCFL
Q1
Q2
1.5V
L1
33µH
D1
1.5V
V
IN
SW
LT1307B
1N4148
1µF
CERAMIC
10k
1
SHDN
GND
FB
CELL
1N4148
V
C
1k
0.1µF
0.1µF
10k
DIMMING
1307 TA08
1 = OPERATE
0 = SHUTDOWN
C1: WIMA MKP-20
D1: MOTOROLA MBR0520L
L1: SUMIDA CD54-330
T1: COILTRONICS CTX110611
Q1, Q2: ZETEX FZT-849
U
PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted.
MS8 Package
8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
0.118 ± 0.004*
0.040 ± 0.006
(1.02 ± 0.15)
0.006 ± 0.004
(0.15 ± 0.10)
(3.00 ± 0.10)
8
7
6
5
0.007
(0.18)
0° – 6° TYP
SEATING
PLANE
0.012
(0.30)
0.118 ± 0.004**
(3.00 ± 0.10)
0.192 ± 0.004
(4.88 ± 0.10)
0.021 ± 0.004
(0.53 ± 0.01)
0.025
(0.65)
TYP
*
DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH,
PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
1
2
3
4
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
MSOP08 0596
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
18
LT1307/ LT1307B
U
PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted.
N8 Package
8-Lead PDIP (Narrow 0.300)
(LTC DWG # 05-08-1510)
0.400*
0.130 ± 0.005
0.300 – 0.325
0.045 – 0.065
(1.143 – 1.651)
(10.160)
MAX
(3.302 ± 0.127)
(7.620 – 8.255)
8
7
6
5
0.065
(1.651)
TYP
0.009 – 0.015
0.255 ± 0.015*
(6.477 ± 0.381)
0.125
(0.229 – 0.381)
0.005
0.015
(3.175)
MIN
(0.127)
MIN
+0.025
–0.015
(0.380)
MIN
0.325
+0.635
–0.381
1
2
4
3
8.255
(
)
0.100 ± 0.010
0.018 ± 0.003
(2.540 ± 0.254)
(0.457 ± 0.076)
N8 0695
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
S8 Package
8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 – 0.197*
(4.801 – 5.004)
7
5
8
6
0.150 – 0.157**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
1
3
4
2
0.010 – 0.020
(0.254 – 0.508)
× 45°
0.053 – 0.069
(1.346 – 1.752)
0.004 – 0.010
(0.101 – 0.254)
0.008 – 0.010
(0.203 – 0.254)
0°– 8° TYP
0.016 – 0.050
0.406 – 1.270
0.050
(1.270)
BSC
0.014 – 0.019
(0.355 – 0.483)
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
SO8 0695
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
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-
tationthattheinterconnectionofits circuits as describedhereinwillnotinfringeonexistingpatentrights.
19
LT1307/ LT1307B
U
TYPICAL APPLICATION
LCD Bias Generator
D1
–V
OUT
0.1µF
1µF
D2
D3
L1
V
OUT
16V TO 24V
5mA FROM 1 CELL
15mA FROM 2 CELLS
35mA FROM 3 CELLS
V
IN
SW
1µF
10pF
LT1307
3.3M
1, 2 OR 3
CELLS
V
C1
FB
C
SHDN
GND
100k
4700pF
1M
215k
1307 TA07
3.3µF
SHUTDOWN
+
L1: 3.3µH (1 CELL)
4.µ7H (2 CELLS)
1µ0H (3 CELLS)
SUMIDA CD43
100k
MURATA-ERIE LQH3C
COILCRAFT D01608
PWM IN 3.3V, 0% TO 100%
C1: µ1F FOR +OUTPUT
0.0µ1F FOR –OUTPUT
D1 TO D3: MBR0530 OR 1N4148
RELATED PARTS
PART NUMBER
LTC®1163
LTC1174
DESCRIPTION
COMMENTS
Triple High Side Driver for 2-Cell Inputs
1.8V Minimum Input, Drives N-Channel MOSFETs
94% Efficiency, 130µA I , 9V to 5V at 300mA
Micropower Step-Down DC/DC Converter
High Output Current Micropower DC/DC Converter
2-Cell Micropower DC/DC Converter
Q
LT1302
5V/600mA from 2V, 2A Internal Switch, 200µA I
Q
LT1304
Low-Battery Detector Active in Shutdown
2.8µA I , Adjustable Hysteresis
LTC1440/1/2
LTC1516
Ultralow Power Single/Dual Comparators with Reference
2-Cell to 5V Regulated Charge Pump
Q
12µA I , No Inductors, 5V at 50mA from 3V Input
Q
LT1521
Micropower Low Dropout Linear Regulator
500mV Dropout, 300mA Current, 12µA I
Q
LT/GP 1196 7K • PRINTED IN THE USA
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
20
●
●
(408) 432-1900 FAX: (408) 434-0507 TELEX: 499-3977
LINEAR TECHNOLOGY CORPORATION 1995
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