LT1307/LT1307B
Single Cell Micropower
600kHz PWM DC/DC Converters
U
FEATURES
■
■
■
■
■
■
■
■
■
■
■
■
DESCRIPTIO
Uses Small Ceramic Capacitors
50µA Quiescent Current (LT1307)
1mA Quiescent Current (LT1307B)
Operates with VIN as Low as 1V
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 Mode® Operation at
Light Load (LT1307)
Continuous Switching at Light Load (LT1307B)
Low VCESAT Switch: 295mV at 500mA
U
APPLICATIO S
■
■
■
■
■
■
■
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 maintained 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
expense of light load efficiency. The devices contain a lowbattery detector with a 200mV reference and shut down to
less than 5µA. No load quiescent current of the LT1307 is
50µA and the internal NPN power switch handles a 500mA
current with a voltage drop of just 295mV.
Unlike competitive devices, large electrolytic capacitors
are not required with the LT1307/LT1307B in single cell
applications. The high frequency (600kHz) switching allows the use of tiny surface mount multilayer ceramic
(MLC) capacitors along with small surface mount inductors. The devices work with just 10µF of output capacitance and require only 1µF of input bypassing.
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 registered trademark of Linear Technology Corporation.
U
TYPICAL APPLICATIO
Single Cell to 3.3V Converter Efficiency
L1
10µH
1.5V
CELL
SHUTDOWN
VIN
LBI
90
SW
FB
LT1307
SHDN
LBO
GND
VC
100k
680pF
R1
1.02M
1%
R2
604k
1%
C1: MURATA-ERIE GRM235Y5V105Z01
MARCON THCS50E1E105Z
TOKIN 1E105ZY5U-C103-F
3.3V
C2: MURATA-ERIE GRM235Y5V106Z01
75mA
MARCON THCS50E1E105Z
TOKIN 1E106ZY5U-C304-F
D1: MOTOROLA MBR0520L
C2
L1: COILCRAFT D01608C-103
10µF
SUMIDA CD43-100
MURATA ERIE LQH3C100
FOR 5V OUTPUT: R1 = 1M, R2 = 329k
80
EFFICIENCY (%)
C1
1µF
D1
VIN = 1.5V
70
VIN = 1V
VIN = 1.25V
60
1307 F01
Figure 1. Single Cell to 3.3V Boost Converter
50
0.1
1
10
LOAD CURRENT (mA)
100
1307 TA01
1307fa
1
LT1307/LT1307B
W W
W
AXI U
U
ABSOLUTE
RATI GS
(Note 1)
VIN, SHDN, LBO Voltage ......................................... 12V
SW Voltage ............................................................. 30V
FB Voltage ....................................................... VIN + 1V
VC Voltage ................................................................ 2V
LBI Voltage ............................................ 0V ≤ VLBI ≤ 1V
Current into FB Pin .............................................. ±1mA
Junction Temperature ........................................... 125°C
Operating Temperature Range
Commercial (Note 2) ......................... – 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
U
U
W
PACKAGE/ORDER I FOR ATIO
ORDER PART
NUMBER
TOP VIEW
VC
FB
SHDN
GND
1
2
3
4
8
7
6
5
LBO
LBI
VIN
SW
TJMAX = 125°C, θJA = 160°C/W
TOP VIEW
LT1307CMS8
LT1307BCMS8
MS8 PACKAGE
8-LEAD PLASTIC MSOP
MS8 PART MARKING
ORDER PART
NUMBER
VC 1
8
LBO
FB 2
7
LBI
SHDN 3
6
VIN
GND 4
5
SW
N8 PACKAGE
8-LEAD PDIP
LTIC
LTIB
S8 PACKAGE
8-LEAD PLASTIC SO
TJMAX = 125°C, θJA = 100°C/W (N8)
TJMAX = 125°C, θJA = 120°C/W (S8)
LT1307CN8
LT1307CS8
LT1307IS8
LT1307BCS8
LT1307BIS8
S8 PART MARKING
1307
1307B
1307I
1307BI
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.
Commercial Grade 0°C to 70°C. VIN = 1.1V, VSHDN = VIN, LT1307/LT1307B unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
IQ
Quiescent Current
Not Switching (LT1307)
Not Switching (LT1307B)
VSHDN = 0V
VFB
Feedback Voltage
IB
FB Pin Bias Current (Note 3)
VFB = VREF
Reference Line Regulation
1V ≤ VIN ≤ 2V (25°C, 0°C)
1V ≤ VIN ≤ 2V (70°C)
2V ≤ VIN ≤ 5V
MIN
●
●
●
●
1.20
●
●
Minimum Input Voltage
Input Voltage Range
gm
Error Amp Transconductance
∆I = 5µA
AV
Error Amp Voltage Gain
25°C, 0°C
70°C
fOSC
Switching Frequency
TYP
MAX
50
1.0
1
90
1.5
3
1.22
1.24
V
27
60
nA
0.6
0.3
1.1
1.5
0.8
%/V
%/V
%/V
0.92
1
V
5
V
65
µmhos
●
1
●
25
35
35
30
100
550
600
●
UNITS
µA
mA
µA
V/V
V/V
750
kHz
1307fa
2
LT1307/LT1307B
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
Commercial Grade 0°C to 70°C. VIN = 1.1V, VSHDN = VIN, LT1307/LT1307B unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
Maximum Duty Cycle
25°C, 0°C
70°C
Switch Current Limit (Note 4)
DC = 40%
DC = 75%
Switch VCESAT
MIN
TYP
80
76
84
MAX
UNITS
%
%
0.6
0.5
1.25
A
A
ISW = 500mA (25°C, 0°C)
ISW = 500mA (70°C)
295
350
400
mV
mV
Burst Mode Operation Switch Current Limit
(LT1307 Only)
L = 10µH
L = 22µH
100
50
Shutdown Pin Current
VSHDN = VIN
VSHDN = 0V
LBI Threshold Voltage
●
2.5
– 1.5
●
●
4.0
– 2.5
µA
µA
200
210
mV
LBO Output Low
ISINK = 10µA
●
0.1
0.25
V
LBO Leakage Current
VLBI = 250mV, VLBO = 5V
●
0.01
0.1
µA
LBI Input Bias Current (Note 5)
VLBI = 150mV
●
5
25
Low-Battery Detector Gain
1MΩ Load (25°C, 0°C)
1MΩ Load (70°C)
Switch Leakage Current
VSW = 5V
Reverse Battery Current
(Note 6)
●
190
mA
mA
1000
500
3000
0.01
●
nA
V/V
V/V
3
750
µA
mA
Commercial Grade TA = – 20°C, VIN = 1.1V, VSHDN = VIN, unless otherwise noted (Note 2).
SYMBOL
PARAMETER
CONDITIONS
IQ
Quiescent Current
VFB = 1.3V, Not Switching (LT1307)
VFB = 1.3V, Not Switching (LT1307B)
VSHDN = 0V
VFB
Feedback Voltage
gm
Error Amp Transconductance
TYP
MAX
UNITS
50
1.1
1
100
1.6
3
µA
mA
µA
1.195
1.22
1.245
25
35
65
AV
Error Amp Voltage Gain
35
100
fOSC
Switching Frequency
500
600
Maximum Duty Cycle
80
84
∆I = 5µA
MIN
V
µmhos
V/V
750
kHz
%
Switch VCESAT
ISW = 500mA, VIN = 1.2V
250
350
mV
Shutdown Pin Current
VSHDN = VIN
VSHDN = 0V
2.5
– 1.5
4.0
– 2.5
µA
µA
200
210
mV
LBI Threshold Voltage
186
1307fa
3
LT1307/LT1307B
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
Industrial Grade – 40°C to 85°C. VIN = 1.1V, VSHDN = VIN, LT1307/LT1307B unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
IQ
Quiescent Current
VFB = 1.3V, Not Switching (LT1307)
VFB = 1.3V, Not Switching (LT1307B)
VSHDN = 0V
VFB
Feedback Voltage
IB
FB Pin Bias Current (Note 3)
VFB = VREF
Reference Line Regulation
1V ≤ VIN ≤ 2V (– 40°C)
1V ≤ VIN ≤ 2V (85°C)
2V ≤ VIN ≤ 5V
Minimum Input Voltage
MIN
●
●
●
●
1.195
●
10
●
– 40°C
85°C
Input Voltage Range
TYP
MAX
UNITS
50
1
1
100
1.8
3
µA
mA
µA
1.22
1.245
27
100
nA
0.6
0.3
1.1
3.2
0.8
%/V
%/V
%/V
1.1
0.8
1.2
1.0
V
V
5
V
65
µmhos
●
gm
Error Amp Transconductance
∆I = 5µA
AV
Error Amp Voltage Gain
– 40°C
85°C
fOSC
Switching Frequency
●
– 40°C
85°C
Switch Current Limit (Note 4)
DC = 40%
DC = 75%
Switch VCESAT
35
35
30
●
Maximum Duty Cycle
25
V
V/V
V/V
500
600
80
75
84
80
750
kHz
%
%
0.6
0.5
1.25
A
A
ISW = 500mA, VIN = 1.2V (– 40°C)
ISW = 500mA (85°C)
250
330
350
400
mV
mV
Burst Mode Operation Switch Current Limit
(LT1307 Only)
L = 10µH
L = 22µH
100
50
Shutdown Pin Current
VSHDN = VIN
VSHDN = 0V
●
●
●
LBI Threshold Voltage
●
186
mA
mA
2.5
– 1.5
4.0
– 2.5
µA
µA
200
210
mV
LBO Output Low
ISINK = 10µA
●
0.1
0.25
V
LBO Leakage Current
VLBI = 250mV, VLBO = 5V
●
0.1
0.3
µA
LBI Input Bias Current (Note 5)
VLBI = 150mV
●
5
30
nA
Low-Battery Detector Gain
1MΩ Load (– 40°C)
1MΩ Load (85°C)
Switch Leakage Current
VSW = 5V
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: 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
tested at – 20°C or 0°C.
Note 3: Bias current flows into FB pin.
1000
400
●
6000
0.01
V/V
V/V
µA
3
Note 4: Switch current limit guaranteed by design and/or correlation to
static tests. Duty cycle affects current limit due to ramp generator.
Note 5: Bias current flows out of LBI pin.
Note 6: The LT1307/LT1307B will withstand continuous application of
1.6V applied to the GND pin while VIN and SW are grounded.
1307fa
4
LT1307/LT1307B
U W
TYPICAL PERFOR A CE CHARACTERISTICS
3.3V Output Efficiency, Circuit of
Figure 1 (LT1307B)
5V Output Efficiency, Circuit of
Figure 1 (LT1307)
90
90
90
80
80
VIN = 1.25V
VIN = 1.5V
60
VIN = 1.25V
60
EFFICIENCY (%)
VIN = 1.00V
70
VIN = 1V
50
40
VIN = 1.5V
30
10
1
LOAD CURRENT (mA)
50
40
20
10
0.1
100 200
VIN = 1V
VIN = 1.25V
60
30
20
50
0.1
VIN = 1.5V
70
70
EFFICIENCY (%)
EFFICIENCY (%)
80
5V Output Efficiency, Circuit of
Figure 1 (LT1307B)
1
10
LOAD CURRENT (mA)
10
0.1
100
LT1307 • G01
1
10
LOAD CURRENT (mA)
1307 G02
1307 G02
Feedback Bias Current vs
Temperature
Quiescent Current vs Temperature
LBI Bias Current vs Temperature
50
80
100
16
VIN = 1.1V
14
60
50
40
30
20
40
LBI BIAS CURRENT (nA)
FEEDBACK BIAS CURRENT (nA)
QUIESCENT CURRENT (µA)
70
30
20
12
10
8
6
4
10
10
2
0
–50
–25
0
50
25
TEMPERATURE (°C)
75
0
–50
100
–25
0
25
50
TEMPERATURE (°C)
75
0
–50
100
–25
0
50
25
TEMPERATURE (°C)
1307 G05
1307 G04
Switch VCESAT vs Current
500
20
10
100
LT1307 • TPC06
Shutdown Pin Bias Current vs
Input Voltage
Quiescent Current in Shutdown
75
8
6
4
2
0
16
12
8
4
0
0
1
3
2
INPUT VOLTAGE (V)
4
5
1307 G07
400
VCESAT (mV)
SHUTDOWN PIN CURRENT (µA)
QUIESCENT CURRENT (µA)
TA = 25°C
300
200
100
0
1
3
2
INPUT VOLTAGE (V)
4
5
1307 G07
0
0
100
500
200
300
400
SWITCH CURRENT (mA)
600
LT1307 • TPC09
1307fa
5
LT1307/LT1307B
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Feedback Voltage vs
Temperature
Oscillator Frequency vs
Input Voltage
LBI Reference vs Temperature
1.230
900
210
208
1.220
1.215
1.210
1.205
800
206
204
FREQUENCY (kHz)
REFERENCE VOLTAGE (mV)
FEEDBACK VOLTAGE (V)
1.225
202
200
198
196
194
25°C
85°C
700
–40°C
600
500
192
1.200
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
190
–50
400
–25
25
50
0
TEMPERATURE (°C)
1307 G10
VOUT
200mV/DIV
AC COUPLED
IL
200mA/DIV
IL
200mA/DIV
ILOAD 55mA
5mA
ILOAD 55mA
5mA
500µs/DIV
VOUT
50mV/DIV
DC
COUPLED
OFFSET
ADDED
ILOAD 20mA/DIV
VIN = 1V
VOUT = 5V
1307 G17
1307 G15
ILOAD 10mA/DIV
1307 G18
Circuit Operation, L = 22µH
(LT1307)
VOUT
50mV/DIV
AC COUPLED
VSW
5V/DIV
VSW
5V/DIV
IL
100mA/DIV
1307 G19
ILOAD 10mA/DIV
Load Regulation (LT1307)
VOUT
50mV/DIV
AC COUPLED
ILOAD 10mA/DIV
VIN = 0.92V
VOUT = 3.3V
Circuit Operation, L = 10µH
(LT1307)
Load Regulation (LT1307)
VIN = 1.15V
VOUT = 5V
Load Regulation (LT1307)
VOUT
50mV/DIV
DC
COUPLED
OFFSET
ADDED
VIN = 1.15V
VOUT = 3.3V
1307 G16
5
LT1307 • TPC12
1307 G14
VOUT
50mV/DIV
DC
COUPLED
OFFSET
ADDED
ILOAD 20mA/DIV
4
INPUT VOLTAGE (V)
Load Regulation (LT1307)
VOUT
50mV/DIV
DC
COUPLED
OFFSET
ADDED
3
2
VOUT
50mV/DIV
DC
COUPLED
OFFSET
ADDED
VIN = 1.25V
VOUT = 3.3V
1307 G13
Load Regulation (LT1307)
VIN = 1V
VOUT = 3.3V
1
Transient Response (LT1307B)
VOUT
200mV/DIV
AC COUPLED
500µs/DIV
100
LT1307 • TPC11
Transient Response (LT1307)
VIN = 1.25V
VOUT = 3.3V
75
IL
100mA/DIV
VIN = 1.25V
VOUT = 5V
ILOAD = 1.5mA
100µs/DIV
1307 G20
VIN = 1.25V
VOUT = 5V
ILOAD = 1.5mA
100µs/DIV
1307 G21
1307fa
6
LT1307/LT1307B
U
U
U
PI FU CTIO S
VC (Pin 1): Compensation Pin for Error Amplifier. Connect a series RC from this pin to ground. Typical values
are 100kΩ and 680pF. Minimize trace area at VC.
SW (Pin 5): Switch Pin. Connect inductor/diode here.
Minimize trace area at this pin to keep EMI down.
VIN (Pin 6): Supply Pin. Must have 1µF ceramic bypass
capacitor right at the pin, connected directly to ground.
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).
LBI (Pin 7): Low-Battery Detector Input. 200mV reference. Voltage on LBI must stay between ground and
700mV.
SHDN (Pin 3): Shutdown. Ground this pin to turn off
switcher. Must be tied to VIN (or higher voltage) to enable
switcher. Do not float the SHDN pin.
LBO (Pin 8): Low-Battery Detector Output. Open collector, can sink 10µA. A 1MΩ pull-up is recommended.
GND (Pin 4): Ground. Connect directly to local ground
plane.
W
BLOCK DIAGRA
VIN
6
VIN
R5
40k
R6
40k
+
VOUT
R1
(EXTERNAL)
FB
R2
(EXTERNAL)
SHDN
VC
gm
1
ERROR
AMPLIFIER
+
SHUTDOWN
–
FB
2
Q1
Q2
×10
LBI
BIAS
–
R4
140k
+
7
*
R3
30k
A1
LBO
8
ENABLE
–
200mV
A4
SW
COMPARATOR
–
RAMP
GENERATOR
3
+
Σ
+
DRIVER
FF
A2
Q3
Q
R
+
5
S
+
A=3
600kHz
OSCILLATOR
0.15Ω
–
4
*HYSTERESIS IN LT1307 ONLY
GND
1307 F02
Figure 2. LT1307/LT1307B Block Diagram
1307fa
7
LT1307/LT1307B
U
W
U U
APPLICATIO S I FOR ATIO
OPERATION
The LT1307 combines a current mode, fixed frequency
PWM architecture with Burst Mode micropower operation
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
VIN is 1V, the feedback voltage of 1.22V, along with an
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 VIN. When there is no load, FB rises slightly
above 1.22V, causing VC (the error amplifier’s output) to
decrease. When VC reaches the bias voltage on hysteretic
comparator A1, A1’s output goes low, turning off all
circuitry except the input stage, error amplifier and lowbattery detector. Total current consumption in this state is
50µA. As output loading causes the FB voltage to decrease, 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 frequency ripple voltage appears at the output. The ripple
frequency is dependent on load current and output capacitance. This Burst Mode operation keeps the output regulated and reduces average current into the IC, resulting in
high efficiency even at load currents of 100µA or less.
If the output load increases sufficiently, A1’s output remains high, resulting in continuous operation. When the
LT1307 is running continuously, peak switch current is
controlled by VC to regulate the output voltage. The switch
is turned on at the beginning of each switch cycle. When
the summation of a signal representing switch current and
a ramp generator (introduced to avoid subharmonic oscillations at duty factors greater than 50%) exceeds the VC
signal, comparator A2 changes state, resetting the flipflop and turning off the switch. Output voltage increases 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
series RC network connected between the VC pin and
ground. Low-battery detector A4’s open collector output
(LBO) pulls low when the LBI pin voltage drops below
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
converter, SHDN must be at VIN or at a higher voltage.
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 in the absence of low frequency output voltage
ripple at the expense of efficiency.
The difference between the two devices is clearly illustrated 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. Load current is stepped from 1mA to 41mA for both
circuits. Low frequency Burst Mode operation voltage
ripple is observed on Trace A, while none is observed on
LT1307
VOUT
TRACE A 500mV/DIV
AC COUPLED
TRACE B
LT1307B
VOUT
500mV/DIV
AC COUPLED
IL 41mA
1mA
VIN = 1.25V
VOUT = 5V
1ms/DIV
1307 F03
Figure 3. LT1307 Exhibits Burst Mode Operation Ripple at
1mA Load, LT1307B Does Not
LT1307
VOUT
TRACE A 200mV/DIV
AC COUPLED
TRACE B
LT1307B
VOUT
200mV/DIV
AC COUPLED
IL 45mA
5mA
VIN = 1.5V
VOUT = 5V
500µs/DIV
1307 F04
Figure 4. At Higher Loading and a 1.5V Supply, LT1307
Again Exhibits Burst Mode Operation Ripple at 5mA Load,
LT1307B Does Not
1307fa
8
LT1307/LT1307B
U
W
U U
APPLICATIO S I FOR ATIO
Trace B. Similarly, Figure 4 details the two circuits with a
load step from 5mA to 45mA with a 1.5V input.
The LT1307B also can be used in lower current applications where a clean, low ripple output is needed. Figure 5
details transient response of a single cell to 3.3V converter, using an inductor value of 100µH. This high inductance 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 VC pin loop compensation has been
made more conservative (increased C, decreased R).
quite evident, as is this particular device’s 575kHz switching frequency (nominal switching frequency is 600kHz).
Note, however, the absence of significant energy at 455kHz.
Figure 7’s plot reduces the frequency span from 255kHz to
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 frequency closer together, moving spectral energy further
IL
20mA/DIV
IL 10mA
5mA
VIN = 1.25V
VOUT = 3.3V
1ms/DIV
1307 F05
OUTPUT NOISE VOLTAGE (dBmVRMS)
40
VOUT
100mV/DIV
AC COUPLED
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
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
20
10
0
–10
–20
–30
–40
–50
–60
10
100
FREQUENCY (kHz)
1
1000
1307 F06
Figure 6. Spectral Noise Plot of 3.3V Converter Delivering
5mA Load. Burst Mode Fundamental at 5.1kHz is 23dBmVRMS
or 14mVRMS
–20
OUTPUT NOISE VOLTAGE (dBmVRMS)
At light loads, the LT1307B will begin to skip alternate
cycles. The load point at which this occurs can be decreased by increasing the inductor value. However, output
ripple will continue to be significantly less than the LT1307
output ripple. Further, the LT1307B can be forced into
micropower mode, where IQ falls from 1mA to 50µA by
pulling down VC to 0.3V or less externally.
RBW = 100Hz
30
–25
RBW = 100Hz
–30
–35
–40
–45
–50
–55
–60
–65
–70
255
455
FREQUENCY (kHz)
655
1307 F07
Figure 7. Span Centered at 455kHz Shows – 55dBmVRMS
(1.8µVRMS) at 455kHz. Burst Mode Creates Sidebands 5.1kHz
Apart Around the Switching Frequency Fundamental of 575kHz
1307fa
9
LT1307/LT1307B
U
W
U U
APPLICATIO S I FOR ATIO
away from 455kHz. Figure 8 shows the noise spectrum of
the converter with the load increased to 20mA. The
LT1307 shifts out of Burst Mode operation, eliminating
low frequency ripple. Spectral energy is present only at
the switching fundamental and its harmonics. Noise
voltage measures – 5dBmVRMS or 560µVRMS at the
575kHz switching frequency, and is below – 60dBmVRMS
for all other frequencies in the range. By combining Burst
Mode with fixed frequency operation, the LT1307 keeps
noise away from 455kHz.
OUTPUT NOISE VOLTAGE (dBmVRMS)
0
To eliminate the low frequency noise of Figure 6, the
LT1307 can be replaced with the LT1307B. Figure 9
details the spectral noise at the output of Figure 1’s circuit
using an LT1307B at 5mA load. Although spectral energy
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
inductance.
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.
RBW = 100Hz
–10
–20
–30
–40
–50
–60
–70
–80
10µH
–90
–100
255
MBR0520L
VOUT
455
FREQUENCY (kHz)
655
VIN
Figure 8. With Converter Delivering 20mA, Low Frequency
Sidebands Disappear. Noise is Present Only at the 575kHz
Switching Frequency
SW
SHDN
LT1307
VC
1307 F08
1µF
66Ω
1M
3300Ω
FB
GND
1.25V
10µF*
R
590k
C
50Ω
OUTPUT VOLTAGE NOISE (dBmVRMS)
0
*CERAMIC
–10
–20
1307 • F10
Figure 10. Boost Converter with Simulated Load
–30
–40
–50
–60
–70
–80
–90
–100
205
455
FREQUENCY (kHz)
705
LT1307 • F09
Figure 9. LT1307B at 5mA Load Shows No Audio Components
or Sidebands About Switching Frequency, 333kHz
Fundamental Amplitude is –10dBmV, or 316µVRMS
Figure 11a details transient response without compensation components. Although the output ripple voltage at a
1mA load is low, allowing the error amplifier to operate
wideband results in excessive ripple at a 50mA load. 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
1307fa
10
LT1307/LT1307B
U
W
U U
APPLICATIO S I FOR ATIO
VOUT
200mV/DIV
AC COUPLED
VOUT
200mV/DIV
AC COUPLED
IL 51mA
1mA
IL 51mA
1mA
5ms/DIV
5ms/DIV
1307 F11a
Figure 11a. VC 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
VOUT
200mV/DIV
AC COUPLED
VOUT
200mV/DIV
AC COUPLED
IL 51mA
1mA
IL 51mA
1mA
1ms/DIV
1307 F11b
500µs/DIV
1307 F11a
Figure 11c. Reducing C to 2nF Speeds Up Response,
Although Still Overdamped
1307 F11b
Figure 11d. A 100k/200pF Series RC Shows Some
Underdamping
VOUT
200mV/DIV
AC COUPLED
IL 51mA
1mA
1ms/DIV
1307 F11b
Figure 11e. A 100k/680pF RC Provides Optimum
Settling Time with No Ringing
underdamping. Now settling time is about 300µs. Increasing C to 680pF results in the response shown in Figure 11e.
This response has minimum settling time with no overshoot or underdamping.
Converters using a 2-cell input need more capacitance at
the output. This added capacitance moves in the output
pole, requiring added C at the VC pin network to prevent
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.
1307fa
11
LT1307/LT1307B
U
W
U U
APPLICATIO S I FOR ATIO
LAYOUT HINTS
COMPONENT SELECTION
The LT1307 switches current at high speed, mandating
careful attention to layout for proper performance. You will
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 CIN must be placed
close (< 5mm) to the IC package. As little as 10mm of wire
or PC trace from CIN to VIN 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 for proper operation. If the battery is located some
distance from the circuit, an additional input capacitor may
be required. A 100µF aluminum electrolytic unit works well
in these cases. This capacitor need not have low ESR.
Inductors
1
R1
R2
CC
KEEP TRACES
OR LEADS SHORT!
LT1307
8
2
7
3
6
Table 1. Inductors Suitable for Use with the LT1307
L
4
5
CIN
AA CELL
RC
Inductors appropriate for use with the LT1307 must possess 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 saturating. This places a lower limit on the physical size of the unit.
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
I2R losses. Linear Technology has identified several inductors 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 components are listed in Table 1.
D
COUT
VOUT
GROUND
PART
VALUE
MAX
DCR
MFR
HEIGHT
(mm)
LQH3C100
10µH
0.57
Murata-Erie
2.0
DO1608-103
10µH
0.16
Coilcraft
3.0
CD43-100
10µH
0.18
Sumida
3.2
CD54-100
10µH
0.10
Sumida
4.5
Best Efficiency
CTX32CT-100
10µH
0.50
Coiltronics
2.2
1210 Footprint
COMMENT
Smallest Size
1307 F12
Figure 12. Recommended Component Placement. Traces
Carrying High Current Are Direct. Trace Area at FB Pin and VC
Pin is Kept Low. Lead Length to Battery Should Be Kept Short
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 situation, an electrolytic capacitor may be required at the circuit
in order to reduce the AC impedance of the input sufficiently. An alternative solution would be to attach the
circuit directly to the power supply at the supply terminals,
without the use of leads. The power supply’s output
capacitance will then provide the bulk capacitance the
LT1307 circuit requires.
Capacitors
For single cell applications, a 10µF ceramic output capacitor 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
ESR tantalum capacitor works well. AVX TPS series (100%
surge tested) or Sprague (don’t be vague—ask for Sprague)
594D series are both good choices for low ESR capacitors.
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-
1307fa
12
LT1307/LT1307B
U
W
U U
APPLICATIO S I FOR ATIO
tions where small size is not critical, Panasonic HFQ series
aluminum electrolytic capacitors have been found to perform well.
Q3
R2
400k
SHUTDOWN
CURRENT
SHDN
Table 2. Vendor Telephone Numbers
VENDOR
COMPONENTS
Coilcraft
Inductors
(708) 639-6400
Marcon
Capacitors
(708) 913-9980
Murata-Erie
VIN
200k
TELEPHONE
Inductors, Capacitors
(404) 436-1300
Sumida
Inductors
(847) 956-0666
Tokin
Capacitors
(408) 432-8020
AVX
Capacitors
(207) 282-5111
Sprague
Capacitors
(603) 224-1961
Coiltronics
Inductors
(407) 241-7876
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.
START-UP
CURRENT
Q2
Q1
1307 F13
Figure 13. Shutdown Circuit
LOW-BATTERY DETECTOR
The LT1307’s low-battery detector is a simple PNP input
gain stage with an open collector NPN output. The negative input of the gain stage is tied internally to a 200mV
±5% reference. The positive input is the LBI pin. Arrangement 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 reference can also be accessed as shown in Figure 15.
3.3V
R1
VIN
LBI
Note that allowing SHDN to float turns on both the startup current (Q2) and the shutdown current (Q3) for VIN >
2VBE. The LT1307 doesn’t know what to do in this situation
and behaves erratically. SHDN voltage above VIN is allowed. This merely reverse-biases Q3’s base emitter junction, a benign condition.
1M
+
LBO
R2
100k
TO PROCESSOR
–
200mV
INTERNAL
REFERENCE
GND
SHUTDOWN PIN
The LT1307 has a Shutdown pin (SHDN) that must be
grounded to shut the device down or tied to a voltage equal
or greater than VIN to operate. The shutdown circuit is
shown in Figure 13.
LT1307
R1 =
VLB – 200mV
2µA
1307 F14
Figure 14. Setting Low-Battery Detector Trip Point
200k
2N3906
VIN
LBO
LT1307
VREF
200mV
10k
LBI
+
10µF
GND
1307 F15
Figure 15. Accessing 200mV Reference
1307fa
13
LT1307/LT1307B
U
W
U U
APPLICATIO S I FOR ATIO
REVERSE BATTERY CONSIDERATIONS
tion after sustaining polarity reversal for the life of a single
AA alkaline cell.
The LT1307 is built on a junction-isolated bipolar process.
The p-type substrate is connected to the GND pin of the
LT1307. Substrate diodes, normally reverse-biased, are
present on the SW pin and the VIN pin as shown in Figure
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.
The LT1307 can withstand this current without damage. In
laboratory tests, the LT1307 performed without degrada-
When using a 2- or 3-cell supply, an external protection
diode is recommended as shown in Figure 18. When the
battery polarity is reversed, the 1N4001 conducts, limiting
reverse voltage across the LT1307 to a single diode drop.
This arrangement will quickly deplete the cells’ energy, but
it does prevent the LT1307 from excessive power dissipation and potential damage.
– 1.5V
1.5V
CURRENT
FLOW
VIN
1 CELL
VIN
SW
SW
1 CELL
D1
LT1307
D2
Q1
D1
LT1307
GND
1307 F16
D2
Q1
GND
1307 F17
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
2 OR 3
CELLS
1N4001
VIN
SW
LT1307
GND
1307 F18
Figure 18. 1N4001 Diode Protects LT1307 from Excessive Power
Dissipation When a 2- or 3-Cell Battery is Used
1307fa
14
LT1307/LT1307B
U
TYPICAL APPLICATIO S
Externally Controlled Burst Mode Operation
L1
10µH
MBR0520
VOUT
1µF
CERAMIC
2
CELLS
300k
VIN
VC
100k
M1
2N7002
1nF
R5
590k
LT1307B
LBO
SHDN
GND
R2
49.9k
SHUTDOWN
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 normally in constant switching mode, 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
VOUT
500mV/DIV
IL
R3
698k
VOUT
3.3V
200mA
LBI
R1
10M
GROUND = HIGH POWER/LOW NOISE
FLOAT = Burst Mode OPERATION
R4
1M
SW
FB
C2*
10µF
CERAMIC
+
C1
100µF
1307 F19
3.0V IN LOW-POWER
Burst Mode OPERATION
C1 = AVX TPSC107K006R0150
L1 = COILCRAFT DO1608-103
SUMIDA CD43-100
* C2 OPTIONAL: REDUCES OUTPUT
RIPPLE CAUSED BY C1'S ESR
detector now drives the VC pin. R3 and R2 set the output
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 VBE, quiescent
current of the LT1307B drops to 60µA, resulting in acceptable efficiency at loads in the 100µA range.
VOUT
100mV/DIV
IL100mA
10mA
10mA
100µA
0.2s/DIV
1307 F20
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.
2ms/DIV
1307 F21
This photo shows transient response in constant switching mode with a 10mA to 100mA stepped load. Output
ripple at the switching frequency can be reduced considerably by adding a 10µF ceramic capacitor in parallel with
the 100µF tantalum.
1307fa
15
LT1307/LT1307B
U
TYPICAL APPLICATIO S
Low Cost 2-Cell to 5V
L1
10µH
VIN
1.4V TO 3.3V
+
1N5818
+
C1*
220µF
6.3V
VIN
SW
LT1307
0.1µF
5V
100mA
C2
220µF
6.3V
1M
SHDN
FB
0.1µF
GND
100k
323k
4700pF
1307 TA02
C1, C2: PANASONIC ECA0JFQ221
(DIGI-KEY P5604-ND)
L1: SUMIDA CD43-100
Step-Up/Step-Down Converter
L1
10µH
VIN
2.1V TO 4.8V
VIN
1µF
CERAMIC
3
CELLS
MBR0520
•
3.3V
100mA
SW
LT1307
VC
100k
2.2µF
CERAMIC
1.02M
FB
SHDN
10µF
CERAMIC
•
L1*
GND
608k
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
VIN
1.8V TO 1V
L1
10µH
3
1µF
VIN
VC
1 CELL
AA OR
AAA
2.2µF
CERAMIC
•
SW
FB
LBO
2200pF
SHDN
1 = CHARGE
0 = SHUTDOWN
1M
•1
OVERVOLTAGE
323k
PROTECTION
LT1307
47k
MBR0520L
2
LBI
GND
4
30k
200mV
15mA
1µF
CERAMIC
3 CELLS
NiCd
–100mV
280k
1nF
6.7Ω
3V
1307 TA04
L1: COILTRONICS CTX10-1
1307fa
16
LT1307/LT1307B
U
TYPICAL APPLICATIO S
Single Cell Powered Constant Current LED Driver
L1
10µH
VIN
D1
100k
D2
VIN
LBO
Q1
2N3906
SW
FB
NC
LT1307B
AA
CELL
VC
GND
SHDN
+
C1
1µF
CERAMIC
LBI
40mA
C3
22µF
C2
1µF
CERAMIC
R2
22k
R1
5.1Ω
100k
1307 TA05
ON/OFF
L1: MURATA-ERIE LQH3C100K04
D1: 1N4148
VIN
C1, C2: CERAMIC
D2, D3: LUMEX SSL-X100133SRC/4 "MEGA-BRITE" RED LED
OR PANASONIC LNG992CF9 HIGH BRIGHTNESS BLUE LED
Flash Memory VPP Supply
VIN
3V TO 5.5V
L1
10µH
+
12V/30mA FROM 3V
12V/60mA FROM 5V
~250mVP-P RIPPLE
0.33µF
1µF
TANTALUM
SHUTDOWN
1N4148
D1
47k
VIN
SW
SHDN
LT1307
VC
2000pF
10pF
0.33µF
CERAMIC
×2
2M
1%
FB
GND
232k
1%
D1: MOTOROLA MBR0520L
L1: MURATA-ERIE LQH3C100K04
1307 TA09
High Voltage Flyback Converter
OPTIONAL
DOUBLER
2VOUT
0.1µF
0.01µF
VIN
1V TO 5V
T1
1:12
1µF
CERAMIC
100k
T1: DALE LPE3325-A190, n = 12 (605) 665-9301
( )
4
VOUT = 1.22V 1 +
1
SHUTDOWN
•
3
1N4148
•
SW
VIN
SHDN
FB
LT1307
VC
GND
6
R1
VOUT
R2
240k
1%
0.1µF
R1
R2
MAXIMUM DUTY CYCLE: ≈80%
FOR FLYBACK, VOUT = DC n(VIN – VSW)
1 – DC
FOR 1VIN, MAXIMUM VOUT = 0.8 12(1 – 0.2) ≈ 37V
1 – 0.8
FOR 2VIN, MAXIMUM VOUT ≈ 85V.
HIGHER VOLTAGES ACHIEVED WITH CAPACITIVE DOUBLER OR TRIPLER
NO SNUBBER REQUIRED WITH SPECIFIED TRANSFORMER AND VIN < 5V
1000pF
1307 TA06
1307fa
17
LT1307/LT1307B
U
TYPICAL APPLICATIO S
Single Cell CCFL Power Supply
6
10
T1
4
5
3
2
1.5V
100Ω
Q1
1.5V
47pF
3kV
1
C1
0.1µF
CCFL
Q2
L1
33µH
D1
1.5V
1µF
CERAMIC
1
CELL
VIN
SW
1N4148
LT1307B
SHDN
FB
10k
1N4148
VC
GND
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 DESCRIPTIO
MS8 Package
8-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1660)
0.889 ± 0.127
(.035 ± .005)
5.23
(.206)
MIN
0.254
(.010)
3.2 – 3.45
(.126 – .136)
DETAIL “A”
0° – 6° TYP
GAUGE PLANE
0.42 ± 0.04
(.0165 ± .0015)
TYP
0.65
(.0256)
BSC
RECOMMENDED SOLDER PAD LAYOUT
0.53 ± 0.015
(.021 ± .006)
DETAIL “A”
1.10
(.043)
MAX
0.86
(.34)
REF
3.00 ± 0.102
(.118 ± .004)
(NOTE 3)
8
7 6 5
0.18
(.077)
SEATING
PLANE
0.22 – 0.38
(.009 – .015)
0.65
(.0256)
BCS
0.13 ± 0.05
(.005 ± .002)
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
0.52
(.206)
REF
3.00 ± 0.102
(.118 ± .004)
NOTE 4
4.88 ± 0.1
(.192 ± .004)
MSOP (MS8) 1001
1
2 3
4
1307fa
18
LT1307/LT1307B
U
PACKAGE DESCRIPTION
N8 Package
8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510)
0.400*
(10.160)
MAX
8
7
6
5
1
2
3
4
0.255 ± 0.015*
(6.477 ± 0.381)
0.300 – 0.325
(7.620 – 8.255)
0.065
(1.651)
TYP
0.009 – 0.015
(0.229 – 0.381)
(
+0.035
0.325 –0.015
8.255
+0.889
–0.381
0.130 ± 0.005
(3.302 ± 0.127)
0.045 – 0.065
(1.143 – 1.651)
)
0.125
(3.175) 0.020
MIN (0.508)
MIN
0.018 ± 0.003
(0.457 ± 0.076)
0.100
(2.54)
BSC
N8 1098
*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 .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)
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
SO8 1298
1307fa
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.
19
LT1307/LT1307B
U
TYPICAL APPLICATIO
LCD Bias Generator
D1
–VOUT
0.1µF
10pF
LT1307
VC
100k
VOUT
16V TO 24V
5mA FROM 1 CELL
15mA FROM 2 CELLS
35mA FROM 3 CELLS
SW
1µF
1, 2 OR 3
CELLS
D2
D3
L1
VIN
1µF
3.3M
C1
FB
SHDN
GND
1M
4700pF
215k
1307 TA07
3.3µF
SHUTDOWN
+
L1: 3.3µH (1 CELL)
4.7µH (2 CELLS)
10µH (3 CELLS)
SUMIDA CD43
MURATA-ERIE LQH3C
COILCRAFT D01608
C1: 1µF FOR +OUTPUT
0.01µF FOR – OUTPUT
D1 TO D3: MBR0530 OR 1N4148
100k
PWM IN 3.3V, 0% TO 100%
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC®1163
Triple High Side Driver for 2-Cell Inputs
1.8V Minimum Input, Drives N-Channel MOSFETs
LTC1174
Micropower Step-Down DC/DC Converter
94% Efficiency, 130µA IQ, 9V to 5V at 300mA
LT1302
High Output Current Micropower DC/DC Converter
5V/600mA from 2V, 2A Internal Switch, 200µA IQ
LT1304
2-Cell Micropower DC/DC Converter
Low-Battery Detector Active in Shutdown
LTC1440/1/2
Ultralow Power Single/Dual Comparators with Reference
2.8µA IQ, Adjustable Hysteresis
LTC1516
2-Cell to 5V Regulated Charge Pump
12µA IQ, No Inductors, 5V at 50mA from 3V Input
LTC3400
600mA, 1.2MHz, Synchronous Boost Converter
92% Efficiency, VIN: 0.85V to 5V, ThinSOTTM Package
LTC3401
1A, 3MHz, Synchronous Boost Converter
97% Efficiency, VIN: 0.5V to 5V, 10-Lead MSOP
LTC3402
2A, 3MHz, Synchronous Boost Converter
97% Efficiency, VIN: 0.5V to 5V, 10-Lead MSOP
ThinSOT is a trademark of Linear Technology Corporation.
1307fa
20
Linear Technology Corporation
LT/TP 1101 1.5K REV A • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
LINEAR TECHNOLOGY CORPORATION 1995
工商网监
湘ICP备2023018690号
