LT3467/LT3467A
1
3467afe
TYPICAL APPLICATION
DESCRIPTION
1.1A Step-Up DC/DC
Converter with
Integrated Soft-Start
The LT
®
3467/LT3467A switching regulators combine a
42V, 1.1A switch with a soft-start function. Pin compatible
with the LT1930, its low VCESAT bipolar switch enables the
device to deliver high current outputs in a small footprint.
The LT3467 switches at 1.3MHz, allowing the use of tiny,
low cost and low height inductors and capacitors. The
LT3467A switches at 2.1MHz, allowing the use of even
smaller components. High inrush current at start-up is
eliminated using the programmable soft-start function.
A single external capacitor sets the current ramp rate. A
constant frequency current mode PWM architecture results
in low, predictable output noise that is easy to fi lter.
The high voltage switch on the LT3467/LT3467A is rated
at 42V, making the devices ideal for boost converters up
to 40V as well as SEPIC and fl yback designs. The LT3467
can generate 5V at up to 540mA from a 3.3V supply or
5V at 450mA from four alkaline cells in a SEPIC design.
The LT3467A can generate 5V at up to 430mA from a 3.3V
supply or 15V at 135mA from a 3.3V supply. The LT3467/
LT3467A are available in a low profi le (1mm) 6-lead SOT-23
package and tiny 3mm × 2mm DFN package.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
Single Li-Ion Cell to 5V Boost Converter
FEATURES
APPLICATIONS
n 1.3MHz Switching Frequency (LT3467)
n 2.1MHz Switching Frequency (LT3467A)
n Low VCESAT Switch: 330mV at 1.1A
n High Output Voltage: Up to 40V
n Wide Input Range: 2.4V to 16V
n Dedicated Soft-Start Pin
n 5V at 540mA from 3.3V Input (LT3467)
n 5V at 430mA from 3.3V Input (LT3467A)
n 12V at 270mA from 5V Input (LT3467)
n 12V at 260mA from 5V Input (LT3467A)
n Uses Small Surface Mount Components
n Low Shutdown Current: <1μA
n Pin-for-Pin Compatible with the LT1930 and LT1613
n Low Profi le (1mm) ThinSOT™ Package
n Low Profi le (0.75mm) 8-Lead (3mm × 2mm)
DFN Package
n Digital Cameras
n White LED Power Supplies
n Cellular Phones
n Medical Diagnostic Equipment
n Local 5V or 12V Supplies
n TFT-LCD Bias Supplies
n xDSL Power Supplies
GND
VIN SW
SS FB
VIN
2.6V TO
4.2V
2.7μH
402k
LT3467
3467 TA01a
15μF
3.3pF
4.7μF
133k
VOUT
5V
765mA AT VIN = 4.2V,
540mA AT VIN = 3.3V,
360mA AT VIN = 2.6V
SHDN
OFF ON
0.047μF
IOUT (mA)
EFFICIENCY (%)
600
95
90
85
80
75
70
65
60
55
50
3467 TA01b
100 900
200 300 400 500 700 800
VIN = 3.3V
VIN = 4.2V
VIN = 2.6V
Effi ciency
LT3467/LT3467A
2
3467afe
VIN Voltage ................................................................16V
SW Voltage ................................................ –0.4V to 42V
FB Voltage ................................................................2.5V
Current Into FB Pin .............................................. ±1mA
SHDN Voltage ......................................................... 16V
Maximum Junction Temperature ......................... 125°C
(Note 1)
ORDER INFORMATION
ABSOLUTE MAXIMUM RATINGS
TOP VIEW
9
DDB PACKAGE
8-LEAD (3mm s 2mm) PLASTIC DFN
5
6
7
8
4
3
2
1FB
GND
SW
SW
SHDN
SS
VIN
GND
TJMAX = 125°C, θJA = 80°C/W
EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB
6 VIN
5 SS
4SHDN
SW 1
TOP VIEW
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
GND 2
FB 3
TJMAX = 125°C, θJA = 165°C/W, θJC = 102°C/W
PIN CONFIGURATION
Operating Junction Temperature Range (Note 2)
E Grade ................................................ –40°C to 85°C
I Grade ............................................... –40°C to 125°C
Storage Temperature Range ................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec)
TSOT ................................................................. 300°C
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LT3467EDDB#PBF LT3467EDDB#TRPBF LCPX 8-Lead (3mm × 2mm) Plastic DFN –40°C to 85°C
LT3467IDDB#PBF LT3467IDDB#TRPBF LCPX 8-Lead (3mm × 2mm) Plastic DFN –40°C to 125°C
LT3467AEDDB#PBF LT3467AEDDB#TRPBF LCKD 8-Lead (3mm × 2mm) Plastic DFN –40°C to 85°C
LT3467AIDDB#PBF LT3467AIDDB#TRPBF LCKD 8-Lead (3mm × 2mm) Plastic DFN –40°C to 125°C
LT3467IS6#PBF LT3467IS6#TRPBF LTACH 6-Lead Plastic TSOT-23 –40°C to 125°C
LT3467ES6#PBF LT3467ES6#TRPBF LTACH 6-Lead Plastic TSOT-23 –40°C to 85°C
LT3467AES6#PBF LT3467AES6#TRPBF LTBCC 6-Lead Plastic TSOT-23 –40°C to 85°C
LT3467AIS6#PBF LT3467AIS6#TRPBF LTBCC 6-Lead Plastic TSOT-23 –40°C to 125°C
LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LT3467EDDB LT3467EDDB#TR LCPX 8-Lead (3mm × 2mm) Plastic DFN –40°C to 85°C
LT3467IDDB LT3467IDDB#TR LCPX 8-Lead (3mm × 2mm) Plastic DFN –40°C to 125°C
LT3467AEDDB LT3467AEDDB#TR LCKD 8-Lead (3mm × 2mm) Plastic DFN –40°C to 85°C
LT3467AIDDB LT3467AIDDB#TR LCKD 8-Lead (3mm × 2mm) Plastic DFN –40°C to 125°C
LT3467IS6 LT3467IS6#TR LTACH 6-Lead Plastic TSOT-23 –40°C to 125°C
LT3467ES6 LT3467ES6#TR LTACH 6-Lead Plastic TSOT-23 –40°C to 85°C
LT3467AES67 LT3467AES6#TR LTBCC 6-Lead Plastic TSOT-23 –40°C to 85°C
LT3467AIS67 LT3467AIS67#TR LTBCC 6-Lead Plastic TSOT-23 –40°C to 125°C
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi ed by a label on the shipping container.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifi cations, go to: http://www.linear.com/tapeandreel/
LT3467/LT3467A
3
3467afe
ELECTRICAL CHARACTERISTICS
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LT3467E/LT3467AE are guaranteed to meet performance
specifi cations from 0°C to 85°C, junction temperature. Specifi cations over
the –40°C to 85°C operating junction temperature range are assured by
design, characterization and correlation with statistical process controls.
The LT3467I/LT3467AI are guaranteed over the full –40°C to 125°C
operating junction temperature range.
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at TA = 25°C. VIN = 3V, VSHDN = VIN unless otherwise noted. Specifi cations are for both
the LT3467 and LT3467A unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Minimum Operating Voltage 2.2 2.4 V
Maximum Operating Voltage 16 V
Feedback Voltage
l
1.230
1.220
1.255 1.270
1.280
V
V
FB Pin Bias Current (Note 3) l10 50 nA
Quiescent Current VSHDN = 2.4V, Not Switching 1.2 2 mA
Quiescent Current in Shutdown VSHDN = 0.5V, VIN = 3V 0.01 1 μA
Reference Line Regulation 2.6V ≤ VIN ≤ 16V 0.01 0.05 %/V
Switching Frequency LT3467
LT3467A
LT3467A l
1
1.6
1.6
1.3
2.1
1.6
2.7
MHz
MHz
MHz
Maximum Duty Cycle LT3467
LT3467
LT3467A
LT3467A
l
l
88
87
82
78
94
88
%
%
%
%
Minimum Duty Cycle 10 %
Switch Current Limit At Minimum Duty Cycle
At Maximum Duty Cycle (Note 4)
1.4
0.8
1.8
1.2
2.5
1.9
A
A
Switch VCESAT ISW = 1.1A 330 500 mV
Switch Leakage Current VSW = 5V 0.01 1 μA
SHDN Input Voltage High 2.4 V
SHDN Input Voltage Low 0.5 V
SHDN Pin Bias Current VSHDN = 3V
VSHDN = 0V
16
0
32
0.1
μA
μA
SS Charging Current VSS = 0.5V 2 3 4.5 μA
Note 3: Current fl ows out of the pin.
Note 4: See Typical Performance Characteristics for guaranteed current
limit vs duty cycle.
LT3467/LT3467A
4
3467afe
TYPICAL PERFORMANCE CHARACTERISTICS
Current Limit vs Duty Cycle
Switch Saturation Voltage
vs Switch Current
Oscillator Frequency
vs Temperature
Soft-Start Current
vs Soft-Start Voltage
Peak Switch Current
vs Soft-Start Voltage
Start-Up Waveform
(Figure 2 Circuit)
Quiescent Current vs Temperature FB Pin Voltage vs Temperature SHDN Current vs SHDN Voltage
IQ(mA)
TEMPERATURE (°C)
–40 95 110
3467 G01
5–10 50
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
–25 3520 65 80 125
VFB (V)
TEMPERATURE (°C)
–40 95 110
3467 G02
5–10 50
1.26
1.25
1.24
1.23
1.22
1.21
1.20 –25 3520 65 80 125
VSHDN (V)
0
ISHDN (μA)
8
140
120
100
80
60
40
20
0
3467 G03
41612
210
61814
TA = 25°C
DC (%)
10
ILIM (A)
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
30 50 60
3467 G04
20 40 70 80 90
TYPICAL
GUARANTEED
TA = 25°C
VCESAT
100mV/DIV
SW CURRENT 200mA/DIV
TA = 85°C
TA = 25°C
TA = –40°C
3467 G05
TEMPERATURE (°C)
–50
OSCILLATOR FREQUENCY (MHz)
100
3467 G06
050–25 25 75
2.50
2.25
2.00
1.75
1.50
1.25
1.00
0.75
0.50
0.25
0
LT3467A
LT3467
VSS (mV)
0 50 150 250 350 450
ISS (μA)
6
5
4
3
2
1
0100 200 300 400
3467 G07
500
TA = 25°C
VSS (mV)
0 50 150 250 350 450
SWITCH CURRENT (A)
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
100 200 300 400
3467 G08
500
TA = 25°C
VSHDN
2V/DIV
VOUT
1V/DIV
ISUPPLY
0.5A/DIV
0.5ms/DIV 3467 G09
LT3467/LT3467A
5
3467afe
PIN FUNCTIONS
(DFN/TSOT)
FB (Pin 1/Pin 3): Feedback Pin. Reference voltage is 1.255V.
Connect resistive divider tap here. Minimize trace area at
FB. Set VOUT = 1.255V(1 + R1/R2).
GND (Pins 2, 5, 9/Pin 2): Ground. Tie directly to local
ground plane.
SW (Pins 3, 4/Pin 1): Switch Pin. (Collector of internal
NPN power switch) Connect inductor/diode here and
minimize the metal trace area connected to this pin to
minimize EMI.
VIN (Pin 6/Pin 6): Input Supply Pin. Must be locally
bypassed.
SS (Pin 7/Pin 5): Soft-Start Pin. Place a soft-start capacitor
here. Upon start-up, 4μA of current charges the capacitor
to 1.255V. Use a larger capacitor for slower start-up. Leave
fl oating if not in use.
SHDN (Pin 8/Pin 4): Shutdown Pin. Tie to 2.4V or more
to enable device. Ground to shut down.
BLOCK DIAGRAM
–
+
–
+
RQ
S
0.01Ω
SW
DRIVER
COMPARATOR
SHDN
VIN
SS
FB
–
+
3
RAMP
GENERATOR
1.255V
REFERENCE
RC
CC
1.3MHz
OSCILLATOR*
GND
3467 F01
Q1
A2
A1
R1 (EXTERNAL)
R2 (EXTERNAL)
FB
VOUT
SHUTDOWN
250k
*2.1MHz FOR LT3467A
Figure 1. Block Diagram
LT3467/LT3467A
6
3467afe
APPLICATIONS INFORMATION
OPERATION
The LT3467 uses a constant frequency, current-mode con-
trol scheme to provide excellent line and load regulation.
Refer to the Block Diagram. At the start of each oscillator
cycle, the SR latch is set which turns on the power switch
Q1. A voltage proportional to the switch current is added
to a stabilizing ramp and the resulting sum is fed into the
positive terminal of the PWM comparator A2. When this
voltage exceeds the level at the negative input of A2, the
SR latch is reset, turning off the power switch. The level
at the negative input of A2 is set by the error amplifi er A1,
and is simply an amplifi ed version of the difference between
the feedback voltage and the reference voltage of 1.255V.
In this manner, the error amplifi er sets the correct peak
current level to keep the output in regulation. If the error
amplifi er’s output increases, more current is delivered to
the output. Similarly, if the error decreases, less current
is delivered. The soft-start feature of the LT3467 allows
for clean start-up conditions by limiting the rate of voltage
rise at the output of comparator A1 which, in turn, limits
the peak switch current. The soft-start pin is connected
to a reference voltage of 1.255V through a 250k resistor,
providing 4μA of current to charge the soft-start capacitor.
Typical values for the soft-start capacitor range from 10nF
to 200nF. The LT3467 has a current limit circuit not shown
in the Block Diagram. The switch current is constantly
monitored and not allowed to exceed the maximum switch
current (typically 1.4A). If the switch current reaches
this value, the SR latch is reset regardless of the state
of comparator A2. This current limit protects the power
switch as well as the external components connected to
the LT3467.
The Block Diagram for the LT3467A (not shown) is identical
except that the oscillator frequency is 2.1MHz.
Duty Cycle
The typical maximum duty cycle of the LT3467 is 94%
(88% for the LT3467A). The duty cycle for a given ap-
plication is given by:
DC =|V
OUT |+|V
D|–|V
IN |
|V
OUT |+|V
D|–|V
CESAT |
where VD is the diode forward voltage drop and VCESAT is
in the worst case 330mV (at 1.1A)
The LT3467 and LT3467A can be used at higher duty cycles,
but must be operated in the discontinuous conduction
mode so that the actual duty cycle is reduced.
Setting Output Voltage
R1 and R2 determine the output voltage.
V
OUT = 1.255V (1+ R1/R2)
Switching Frequency and Inductor Selection
The LT3467 switches at 1.3 MHz, allowing for small valued
inductors to be used. 4.7μH or 10μH will usually suffi ce.
The LT3467A switches at 2.1MHz, allowing for even smaller
valued inductors to be used. 0.9μH to 6.8μH will usually
suffi ce. Choose an inductor that can handle at least 1.2A
without saturating, and ensure that the inductor has a
low DCR (copper-wire resistance) to minimize I2R power
losses. Note that in some applications, the current handling
requirements of the inductor can be lower, such as in the
SEPIC topology where each inductor only carries one-half
of the total switch current. For better effi ciency, use similar
valued inductors with a larger volume. Many different sizes
and shapes are available from various manufacturers.
Choose a core material that has low losses at 1.3MHz,
(2.1MHz for the LT3467A) such as ferrite core.
LT3467/LT3467A
7
3467afe
APPLICATIONS INFORMATION
GND
VIN SW
SS FB
VIN
2.6V TO 4.2V
D1
L1
2.7μH
R1
402k
LT3467
3467 TA05a
C2
15μF
C4
3.3pF
C1
4.7μF
R2
133k
VOUT
5V
765mA AT VIN = 4.2V,
540mA AT VIN = 3.3V,
360mA AT VIN = 2.6V
C1, C2: X5R OR X7R, 6.3V
D1: ON SEMICONDUCTOR MBRM120
L1: SUMIDA CR43-2R7
SHDN
OFF ON
C3
0.047μF
Figure 2. Single Li-Ion Cell to 5V Boost Converter (Same as 1st Page Application)
Table 1. Inductor Manufacturers
Sumida (847) 956-0666 www.sumida.com
TDK (847) 803-6100 www.tdk.com
Murata (714) 852-2001 www.murata.com
FDK (408) 432-8331 www.fdk.co.jp
Soft-Start
The soft-start feature provides a way to limit the inrush
current drawn from the supply upon start-up. An internal
250k resistor charges the external soft-start capacitor
to 1.255V. After the capacitor reaches 0.15V the rate of
voltage rise at the output of the comparator A1 tracks the
rate of voltage rise of the soft-start capacitor. This limits
the inrush current drawn from the supply during start-
up. The soft-start feature plays another important role in
applications where the switch will reach levels of 30V or
higher. During start-up, excessively high switch current,
together with the presence of high voltage can overstress
the switch. A properly used soft-start feature will keep the
switch current from overshooting. This practice will greatly
improve the robustness of such designs. Once the part is
shut down, the soft-start capacitor is quickly discharged
to 0.4V, then slowly discharged through the 250k resistor
to ground. If the part is to be shut down and re-enabled in
a short period of time while soft-start is used, you must
ensure that the soft-start capacitor has enough time to
discharge before re-enabling the part. Typical values of
the soft-start capacitor range from 10nF to 200nF.
Supply Current of Figure 2 During Start-Up
Without Soft-Start Capacitor
VOUT
1V/DIV
ISUPPLY
0.5A/DIV
0.1ms/DIV 3467 AI01
Supply Current of Figure 2 During Start-Up
with a 47nF Soft-Start Capacitor
VOUT
1V/DIV
ISUPPLY
0.5A/DIV
0.5ms/DIV 3467 AI02
LT3467/LT3467A
8
3467afe
APPLICATIONS INFORMATION
Capacitor Selection
Low ESR (equivalent series resistance) capacitors should
be used at the output to minimize the output ripple voltage.
Multi-layer ceramic capacitors are an excellent choice,
as they have extremely low ESR and are available in very
small packages. X5R dielectrics are preferred, followed
by X7R, as these materials retain the capacitance over
wide voltage and temperature ranges. A 4.7μF to 15μF
output capacitor is suffi cient for most applications, but
systems with very low output currents may need only a
1μF or 2.2μF output capacitor. Solid tantalum or OS-CON
capacitors can be used, but they will occupy more board
area than a ceramic and will have a higher ESR. Always
use a capacitor with a suffi cient voltage rating.
Ceramic capacitors also make a good choice for the input
decoupling capacitor, which should be placed as close as
possible to the LT3467. A 1μF to 4.7μF input capacitor
is suffi cient for most applications. Table 2 shows a list
of several ceramic capacitor manufacturers. Consult the
manufacturers for detailed information on their entire
selection of ceramic parts.
Table 2. Ceramic Capacitor Manufacturers
Taiyo Yuden (408) 573-4150 www.t-yuden.com
AVX (803) 448-9411 www.avxcorp.com
Murata (714) 852-2001 www.murata.com
The decision to use either low ESR (ceramic) capacitors
or the higher ESR (tantalum or OS-CON) capacitors can
affect the stability of the overall system. The ESR of any
capacitor, along with the capacitance itself, contributes
a zero to the system. For the tantalum and OS-CON ca-
pacitors, this zero is located at a lower frequency due to
the higher value of the ESR, while the zero of a ceramic
capacitor is at a much higher frequency and can generally
be ignored.
A phase lead zero can be intentionally introduced by placing
a capacitor (C4) in parallel with the resistor (R1) between
VOUT and VFB as shown in Figure 2. The frequency of the
zero is determined by the following equation.
ƒZ=1
2π•R1•C4
By choosing the appropriate values for the resistor and
capacitor, the zero frequency can be designed to improve
the phase margin of the overall converter. The typical
target value for the zero frequency is between 35kHz
to 55kHz. Figure 3 shows the transient response of the
step-up converter from Figure 8 without the phase lead
capacitor C4. Although adequate for many applications,
phase margin is not ideal as evidenced by 2-3 “bumps”
in both the output voltage and inductor current. A 22pF
capacitor for C4 results in ideal phase margin, which is
revealed in Figure 4 as a more damped response and less
overshoot.
Diode Selection
A Schottky diode is recommended for use with the LT3467
and the LT3467A. The Philips PMEG 2005 is a very good
choice. Where the switch voltage exceeds 20V, use the
PMEG 3005 (a 30V diode). Where the switch voltage
exceeds 30V, use the PMEG 4005 (a 40V diode). These
diodes are rated to handle an average forward current of
0.5A. In applications where the average forward current
of the diode exceeds 0.5A, a Philips PMEG 2010 rated at
1A is recommended. For higher effi ciency, use a diode
with better thermal characteristics such as the On Semi-
conductor MBRM120 (a 20V diode) or the MBRM140 (a
40V diode).
LT3467/LT3467A
9
3467afe
APPLICATIONS INFORMATION
VOUT
200mV/DIV
AC COUPLED
IL1
5A/DIV
AC COUPLED
LOAD CURRENT
100mA/DIV
AC COUPLED
20μs/DIV 3467 F03
Figure 3. Transient Response of Figure 8’s Step-Up
Converter without Phase Lead Capacitor
VOUT
200mV/DIV
AC COUPLED
IL1
5A/DIV
AC COUPLED
LOAD CURRENT
100mA/DIV
AC COUPLED
20μs/DIV 3467 F04
Figure 4. Transient Response of Figure 8’s Step-Up
Converter with a 22pF Phase Lead Capacitor
Setting Output Voltage
To set the output voltage, select the values of R1 and R2
(see Figure 2) according to the following equation.
R1=R2 VOUT
1.255V –1
⎛
⎝
⎜⎞
⎠
⎟
A good value for R2 is 13.3k which sets the current in the
resistor divider chain to 1.255V/13.3k = 94μA.
Layout Hints
The high speed operation of the LT3467/LT3467A demands
careful attention to board layout. You will not get adver-
tised performance with careless layout. Figure 5a shows
the recommended component placement for the ThinSOT
package. Figure 5b shows the recommended component
placement for the DFN package. Note the vias under the
Exposed Pad. These should connect to a local ground
plane for better thermal performance.
R2
R1
GND
C2
C3
L1
D1 C1
VOUT
VOUT
VIN
SHDN
3467 F05a
FB
CSS
SS
1
2
3
6
5
4
Figure 5a. Suggested Layout—ThinSOT
R2
R1
GND
C2
C1
L1
D1
VOUT
VOUT
3467 F05b
C3
FB
CSS
VIN
1
2
3
4
8
7
6
5
SHDN
Figure 5b. Suggested Layout—DFN
LT3467/LT3467A
10
3467afe
APPLICATIONS INFORMATION
Compensation—Theory
Like all other current mode switching regulators, the
LT3467/LT3467A needs to be compensated for stable
and effi cient operation. Two feedback loops are used in
the LT3467/LT3467A: a fast current loop which does not
require compensation, and a slower voltage loop which
does. Standard Bode plot analysis can be used to under-
stand and adjust the voltage feedback loop.
As with any feedback loop, identifying the gain and phase
contribution of the various elements in the loop is critical.
Figure 6 shows the key equivalent elements of a boost
converter. Because of the fast current control loop, the
power stage of the IC, inductor and diode have been re-
placed by the equivalent transconductance amplifi er gmp.
gmp acts as a current source where the output current is
proportional to the VC voltage. Note that the maximum
output current of gmp is fi nite due to the current limit
in the IC.
From Figure 6, the DC gain, poles and zeroes can be
calculated as follows:
Output Pole: P1= 2
2•π•RL•C
OUT
Error Amp Pole: P2= 1
2•π•RO•C
C
Error Amp Zero: Z1= 1
2•π•RC•C
C
DC GAIN: A= 1.255
VOUT2•V
IN •g
ma •RO•g
mp •RL•1
2
ESR Zero: Z2 =1
2•π•RESR •C
OUT
RHP Zero: Z3= VIN2•RL
2•π•V
OUT2•L
High Frequency Pole: P3> fS
3
Phase Lead Zero: Z4 =1
2•π•R1•CPL
Phase Lead Pole: P4 =1
2•π•C
PL •R1• R2
R1+R2
The current mode zero is a right-half plane zero which can
be an issue in feedback control design, but is manageable
with proper external component selection.
–
+
–
+
gma
RCRO
R2
CC: COMPENSATION CAPACITOR
COUT: OUTPUT CAPACITOR
CPL: PHASE LEAD CAPACITOR
gma: TRANSCONDUCTANCE AMPLIFIER INSIDE IC
gmp: POWER STAGE TRANSCONDUCTANCE AMPLIFIER
RC: COMPENSATION RESISTOR
RL: OUTPUT RESISTANCE DEFINED AS VOUT DIVIDED BY ILOAD(MAX)
RO: OUTPUT RESISTANCE OF gma
R1, R2: FEEDBACK RESISTOR DIVIDER NETWORK
RESR: OUTPUT CAPACITOR ESR
3467 F06
R1
COUT
CPL RL
RESR
VOUT
VC
CC
gmp
1.255V
REFERENCE
Figure 6. Boost Converter Equivalent Model
LT3467/LT3467A
11
3467afe
APPLICATIONS INFORMATION
Using the circuit of Figure 2 as an example, the following
table shows the parameters used to generate the Bode
plot shown in Figure 7.
Table 3. Bode Plot Parameters
PARAMETER VALUE UNITS COMMENT
RL10.4 Ω Application Specifi c
COUT 15 μF Application Specifi c
RESR 10 mΩ Application Specifi c
RO0.4 MΩ Not Adjustable
CC60 pF Not Adjustable
CPL 3.3 pF Adjustable
RC100 kΩ Not Adjustable
R1 402 kΩ Adjustable
R2 133 kΩ Adjustable
VOUT 5 V Application Specifi c
VIN 3.3 V Application Specifi c
gma 35 μmho Not Adjustable
gmp 7.5 mho Not Adjustable
L 2.7 μH Application Specifi c
fS1.3* MHz Not Adjustable
*2.1MHz for LT3467A
From Figure 7, the phase is –138° when the gain reaches
0dB giving a phase margin of 42°. This is more than
adequate. The crossover frequency is 37kHz.
FREQUENCY (Hz)
GAIN (dB)
PHASE (DEG)
50
40
30
20
10
0
–10
–20
–30
–40
–50
0
–45
–90
–135
–180
–225
–270
–315
–360
–405
–450
100 10k 100k 1M
3467 F07
1k
GAIN
PHASE
Figure 7. Bode Plot of 3.3V to 5V Application
TYPICAL APPLICATIONS
Lithium-Ion to 6V Step-Up DC/DC Converter
GND
VIN SW
SHDN
FB
VIN
2.7V TO 4.2V
D1
L1
2.2μH
R1
501k
LT3467
3467 TA02
C2
15μF
C3
1.8pF
C1
2.2μF
R2
133k
VOUT
6V
275mA AT VIN = 2.7V
490mA AT VIN = 3.8V
590mA AT VIN = 4.2V
C1, C2: X5R OR X7R, 6.3V
D1: ON SEMICONDUCTOR MBRM120
L1: SUMIDA CR43-2R2
SHDN
SS
C4
0.047μF
IOUT (mA)
EFFICIENCY (%)
200
95
90
85
80
75
70
65
60
55
50
3467 TA02b
10050 300 400 500 600 700
VIN = 3.8V
VIN = 4.2V
VIN = 2.7V
Li-Ion to 6V
LT3467/LT3467A
12
3467afe
TYPICAL APPLICATIONS
4-Cell to 5V SEPIC Converter
GND
VIN SW
SHDN
FB
4V TO 6.5V D1
L1
10μH
L2
10μH
255k
LT3467
3467 TA03
C1
2.2μF
C4
0.047μF
4-CELL
BATTERY C2
10μF
C3
1μF
84.5k
VOUT
5V
325mA AT VIN = 4V
400mA AT VIN = 5V
450mA AT VIN = 6.5V
C1, C3: X5R or X7R, 10V
C2: X5R or X7R, 6.3V
SHDN
SS
C5
4.7pF
D1: PHILIPS PMEG 2010
L1, L2: MURATA LQH32CN100K33L
5V to 40V Boost Converter
GND
VIN SW
SHDN
FB
VIN
5V
D1
L1
2.7μH
R1
412k
LT3467
3467 TA04a
C2
1μF
C1
4.7μF
C3
0.1μF
R2
13.3k
VOUT
40V
20mA
C1: X5R or X7R, 6.3V
C2: X5R or X7R, 50V
D1: ON SEMICONDUCTOR, MBRM140
L1: SUMIDA CD43-2R7
SHDN
SS
±15V Dual Output Converter with Output Disconnect
GND
VIN SW
SS FB
VIN
5V
D1
C4
1μF
D2
L1
10μH
R1
147k
C5
1μF
C6
0.047μF
LT3467
D3 D4
3467 TA05
C2
2.2μF
C3
2.2μF
C1
2.2μF R3
1Ω
R2
13.3k
–15V
100mA
15V
100mA
C1: X5R or X7R, 6.3V
C2 TO C5: X5R or X7R, 16V
D1 TO D4: PHILIPS PMEG 2005
L1: SUMIDA CR43-100
SHDN
OFF ON
R4
1Ω
LT3467/LT3467A
13
3467afe
TYPICAL APPLICATIONS
9V, 18V, –9V Triple Output TFT-LCD Bias Supply with Soft-Start
GND
VIN SW
FB
VIN
3.3V
D5
L1
4.7μH
R1
124k
LT3467
3467 TA06a
C5
10μF
C4
1μF
C1
2.2μF
C2
0.1μF
C6
1μF
R2
20k
9V
220mA
–9V
10mA
18V
10mA
C1: X5R OR X7R, 6.3V
C2,C3, C5, C6: X5R OR X7R, 10V
C4: X5R OR X7R, 25V
D1 TO D4: PHILIPS BAT54S OR EQUIVALENT
D5: PHILIPS PMEG 2005
L1: PANASONIC ELT5KT4R7M
SS
VSHDN SHDN
3.3V
0V C7
0.1μF
D1
D4
D3
D2
C3
0.1μF
IL1
0.5A/DIV
9V OUTPUT
5V/DIV
18V OUTPUT
10V/DIV
–9V OUTPUT
5V/DIV
2ms/DIV 3467 TA06b
Start-Up Waveforms
8V, 23V, –8V Triple Output TFT-LCD Bias Supply with Soft-Start
IL1
0.5A/DIV
8V OUTPUT
5V/DIV
23V OUTPUT
10V/DIV
–8V OUTPUT
5V/DIV
2ms/DIV 3467 TA07b
Start-Up Waveforms
GND
VIN SW
SS FB
VIN
3.3V
D7
L1
4.7μH
R1
113k
LT3467
3467 TA07a
C7
10μF
C6
1μF
C1
2.2μF
C2
0.1μF
C8
1μF
R2
21k
8V
270mA
–8V
10mA
23V
10mA
C1: X5R OR X7R, 6.3V
C2 TO C4, C7, C8: X5R OR X7R, 10V
C5: X5R OR X7R, 16V
C6: X5R OR X7R, 25V
D1 TO D6: PHILIPS BAT54S OR EQUIVALENT
D7: PHILIPS PMEG 2005
L1: PANASONIC ELT5KT4R7M
3.3V
0V C9
0.1μF
D1
D5
D6
D2
C3
0.1μF
C4
0.1μF
C5
0.1μF
D3 D4
SHDN
VSHDN
LT3467/LT3467A
14
3467afe
TYPICAL APPLICATIONS
GND
VIN SW
SHDN
FB
VIN
2.6V TO 4.2V
D1
L1
0.9μH
R1
8.06k
LT3467A
3467 TA09a
C2*
22μF
C4*
75pF
C1
4.7μF
R2
2.67k
VOUT
5V
600mA AT VIN = 4.2V
360mA AT VIN = 3.3V
250mA AT VIN = 2.6V
C1, C2: X5R OR X7R, 6.3V
D1: PHILIPS PMEG 2010
L1: FDK MIPW3226D0R9M
*C2 CAN BE 10μF IN A 1210 OR LARGER PACKAGE WITH
THE ADDITION OF C4, OTHERWISE C4 IS OPTIONAL
SS
C3
0.047μF
OFF ON
IOUT (mA)
EFFICIENCY (%)
95
90
85
80
75
70
65
60
55
50 400
3467 TA09b
10050 150 250 350 450
200 300 500
VIN = 3.3V
VIN = 4.2V
VIN = 2.6V
Single Li-Ion Cell to 5V Boost Converter Effi ciency
2.6V-3.3V to 5V Boost Converter Effi ciency
GND
VIN SW
SHDN
FB
VIN
2.6V TO 3.3V
D1
L1
1.5μH
R1
8.06k
LT3467A
3467 TA08a
C2
10μF
C4
56pF
C1
4.7μF
R2
2.67k
VOUT
5V
430mA AT VIN = 3.3V
270mA AT VIN = 2.6V
C1, C2: X5R OR X7R, 6.3V
D1: PHILIPS PMEG 2010
L1: FDK MIP3226D1R5M
SS
C3
0.047μF
OFF ON
IOUT (mA)
EFFICIENCY (%)
90
85
80
75
70
65
60
55
50 400
3467 TA08b
10050 150 250 350 450
200 300 500
VIN = 3.3V
VIN = 2.6V
3.3V to 15V, 135mA Step-Up Converter Effi ciency
GND
VIN SW
SHDN
FB
VIN
3.3V
D1
L1
6.8μH
R1
16.5k
LT3467A
3467 TA10a
C2
2.2μF
C4
68pF
C1
4.7μF
R2
1.5k
VOUT
15V
135mA
C1: X5R OR X7R, 6.3V
C2: X5R OR X7R, 16V
D1: PHILIPS PMEG 2010
L1: SUMIDA CMD4D13-6R8MC
SS
C3
0.047μF
OFF ON
IOUT (mA)
EFFICIENCY (%)
3467 TA10b
90
80
70
60
50
40
30 40 80 100
20 60 120 140 160
LT3467/LT3467A
15
3467afe
PACKAGE DESCRIPTION
DDB Package
8-Lead Plastic DFN (3mm × 2mm)
(Reference LTC DWG # 05-08-1702 Rev B)
2.00 p0.10
(2 SIDES)
NOTE:
1. DRAWING CONFORMS TO VERSION (WECD-1) IN JEDEC PACKAGE OUTLINE M0-229
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE
0.40 p 0.10
BOTTOM VIEW—EXPOSED PAD
0.56 p 0.05
(2 SIDES)
0.75 p0.05
R = 0.115
TYP
R = 0.05
TYP
2.15 p0.05
(2 SIDES)
3.00 p0.10
(2 SIDES)
14
85
PIN 1 BAR
TOP MARK
(SEE NOTE 6)
0.200 REF
0 – 0.05
(DDB8) DFN 0905 REV B
0.25 p 0.05
2.20 p0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
0.61 p0.05
(2 SIDES)
1.15 p0.05
0.70 p0.05
2.55 p0.05
PACKAGE
OUTLINE
0.25 p 0.05
0.50 BSC
PIN 1
R = 0.20 OR
0.25 s 45o
CHAMFER
0.50 BSC
LT3467/LT3467A
16
3467afe
1.50 – 1.75
(NOTE 4)
2.80 BSC
0.30 – 0.45
6 PLCS (NOTE 3)
DATUM ‘A’
0.09 – 0.20
(NOTE 3) S6 TSOT-23 1005
2.90 BSC
(NOTE 4)
0.95 BSC
1.90 BSC
0.80 – 0.90
1.00 MAX 0.01 – 0.10
0.20 BSC
0.30 – 0.50 REF
PIN ONE ID
NOTE:
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193
3.85 MAX
0.62
MAX
0.95
REF
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
1.4 MIN
2.62 REF
1.22 REF
S6 Package
6-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1636)
PACKAGE DESCRIPTION
LT3467/LT3467A
17
3467afe
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
REVISION HISTORY
REV DATE DESCRIPTION PAGE NUMBER
E 04/10 Updated Note 2 in Absolute Maximum Ratings and Electrical Characteristics 2, 3
(Revision history begins at Rev E)
LT3467/LT3467A
18
3467afe
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2003
LT 0410 REV E • PRINTED IN USA
RELATED PARTS
TYPICAL APPLICATIONS
PART NUMBER DESCRIPTION COMMENTS
LT1615/LT1615-1 300mA/80mA (ISW), High Effi ciency Step-Up DC/DC Converter VIN: 1V to 15V, VOUT(MAX) = 34V, IQ = 20μA, ISD < 1μA,
ThinSOT Package
LT1618 1.5A (ISW), 1.25MHz, High Effi ciency Step-Up DC/DC Converter 90% Effi ciency, VIN: 1.6V to 18V, VOUT(MAX) = 35V, IQ = 1.8mA,
ISD < 1μA, MS Package
LTC1700 No RSENSE™, 530kHz, Synchronous Step-Up DC/DC Controller 95% Effi ciency, VIN: 0.9V to 5V, IQ = 200μA, ISD < 10μA,
MS Package
LTC1871 Wide Input Range, 1MHz, No RSENSE Current Mode Boost,
Flyback and SEPIC Controller
92% Effi ciency, VIN: 2.5V to 36V, IQ = 250μA, ISD < 10μA,
MS Package
LT1930/LT1930A 1A (ISW), 1.2MHz/2.2MHz, High Effi ciency Step-Up
DC/DC Converter
High Effi ciency, VIN: 2.6V to 16V, VOUT(MAX) = 34V,
IQ = 4.2mA/5.5mA, ISD < 1μA, ThinSOT Package
LT1946/LT1946A 1.5A (ISW), 1.2MHz/2.7MHz, High Effi ciency Step-Up
DC/DC Converter with Soft-Start
High Effi ciency, VIN: 2.45V to 16V, VOUT(MAX) = 34V, IQ = 3.2mA,
ISD < 1μA, MS8 Package
LT1961 1.5A (ISW), 1.25MHz, High Effi ciency Step-Up DC/DC Converter 90% Effi ciency, VIN: 3V to 25V, VOUT(MAX) = 35V, IQ = 0.9mA,
ISD < 6μA, MS8E Package
LTC3400/
LTC3400B
600mA (ISW), 1.2MHz, Synchronous Step-Up DC/DC Converter 92% Effi ciency, VIN: 0.85V to 5V, VOUT(MAX) = 5V,
IQ = 19μA/300μA, ISD < 1μA, ThinSOT Package
LTC3401 1A (ISW), 3MHz, Synchronous Step-Up DC/DC Converter 97% Effi ciency, VIN: 0.5V to 5V, VOUT(MAX) = 5.5V, IQ = 38μA,
ISD < 1μA, MS Package
LTC3402 2A (ISW), 3MHz, Synchronous Step-Up DC/DC Converter 97% Effi ciency, VIN: 0.5V to 5V, VOUT(MAX) = 5.5V, IQ = 38μA,
ISD < 1μA, MS Package
LT3464 85mA (ISW), High Effi ciency Step-Up DC/DC Converter with
Integrated Schottky and PNP Disconnect
VIN: 2.3V to 10V, VOUT(MAX) = 34V, IQ = 25μA, ISD < 1μA,
ThinSOT Package
No RSENSE is a trademark of Linear Technology Corporation.
GND
VIN SW
SS FB
VIN
5V
D1
L1
4.7μH
R1
115k
LT3467
3467 F08a
C2
10μF
C4*
22pF
C1
2.2μF
C3
0.047μF R2
13.3k
VOUT
12V
270mA
C1: X5R OR X7R, 6.3V
C2: X5R OR X7R, 16V
D1: PHILIPS PMEG 2010
L1: SUMIDA CR43-4R7
*OPTIONAL
SHDNSHDN
IOUT (mA)
50
EFFICIENCY (%)
100 250200150 300 350
3467 F08b
90
85
80
75
70
65
60
55
50
Effi ciency
Figure 8. 5V to 12V, 270mA Step-Up Converter
Effi ciency
IOUT (mA)
EFFICIENCY (%)
200
95
90
85
80
75
70
65
60
55
50
3467 F09b
10050 150 250 300
GND
VIN SW
SHDN
FB
VIN
5V
D1
L1
3.3μH
R1
115k
LT3467A
3467 F09a
C2
10μF
C4
12pF
C1
4.7μF
R2
13.3k
VOUT
12V
260mA
C1: X5R OR X7R, 6.3V
C2: X5R OR X7R, 16V
D1: PHILIPS PMEG 2010
L1: SUMIDA CDRH4D18-3R3
SS
C3
0.047μF
OFF ON
Figure 9. 5V to 12V, 260mA Step-Up Converter
