1
LT3467/LT3467A
3467afc
APPLICATIO S
U
DESCRIPTIO
U
FEATURES
TYPICAL APPLICATIO
U
1.1A Step-Up DC/DC
Converter with
Integrated Soft-Start
■
1.3MHz Switching Frequency (LT3467)
■
2.1MHz Switching Frequency (LT3467A)
■
Low V
CESAT
Switch: 330mV at 1.1A
■
High Output Voltage: Up to 40V
■
Wide Input Range: 2.4V to 16V
■
Dedicated Soft-Start Pin
■
5V at 540mA from 3.3V Input (LT3467)
■
5V at 430mA from 3.3V Input (LT3467A)
■
12V at 270mA from 5V Input (LT3467)
■
12V at 260mA from 5V Input (LT3467A)
■
Uses Small Surface Mount Components
■
Low Shutdown Current: <1μA
■
Pin-for-Pin Compatible with the LT1930 and LT1613
■
Low Profile (1mm) ThinSOT
™
Package
■
Low Profile (0.75mm) 8-Lead (3mm x 2mm)
DFN Package
Single Li-Ion Cell to 5V Boost Converter
■
Digital Cameras
■
White LED Power Supplies
■
Cellular Phones
■
Medical Diagnostic Equipment
■
Local 5V or 12V Supplies
■
TFT-LCD Bias Supplies
■
xDSL Power Supplies
The LT
®
3467/LT3467A switching regulators combine a
42V, 1.1A switch with a soft-start function. Pin compatible
with the LT1930, its low V
CESAT
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 re-
sults in low, predictable output noise that is easy to filter.
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 flyback 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 profile (1mm) 6-lead
SOT-23 package and tiny 3mm x 2mm DFN package.
GND
V
IN
SW
SS FB
V
IN
2.6V TO
4.2V
2.7μH
402k
LT3467
3467 TA01a
15μF
3.3pF
4.7μF
133k
V
OUT
5V
765mA AT V
IN
= 4.2V,
540mA AT V
IN
= 3.3V,
360mA AT V
IN
= 2.6V
SHDN
OFF ON
0.047μF
Efficiency
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
, LT, LTC and LTM 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.
2
LT3467/LT3467A
3467afc
T
JMAX
= 125°C, θ
JA
= 80°C/ W
EXPOSED PAD (PIN 9) IS GROUND
(MUST BE SOLDERED TO PCB)
ABSOLUTE AXI U RATI GS
WWWU
TOP VIEW
9
DDB PACKAGE
8-LEAD (3mm × 2mm) PLASTIC DFN
5
6
7
8
4
3
2
1FB
GND
SW
SW
SHDN
SS
VIN
GND
(Note 1)
T
JMAX
= 125°C, θ
JA
= 165°C/ W, θ
JC
= 102°C/ W
6 VIN
5 SS
4 SHDN
SW 1
TOP VIEW
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
GND 2
FB 3
V
IN
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
Operating 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 Only) ........................................................... 300°C
PI CO FIGURATIO
UUU
ORDER I FOR ATIO
UUW
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
LT3467AEDDB#PBF LT3467AEDDB#TRPBF LCKD 8-Lead (3mm × 2mm) Plastic DFN –40°C to 85°C
LT3467IS6#PBF LT3467IS6#TRPBF LTACH 6-Lead Plastic TSOP-23 –40°C to 125°C
LT3467ES6#PBF LT3467ES6#TRPBF LTACH 6-Lead Plastic TSOP-23 –40°C to 85°C
LT3467AES6#PBF LT3467AES6#TRPBF LTBCC 6-Lead Plastic TSOP-23 –40°C to 85°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
LT3467AEDDB LT3467AEDDB#TR LCKD 8-Lead (3mm × 2mm) Plastic DFN –40°C to 85°C
LT3467IS5 LT3467IS6#TR LTACH 6-Lead Plastic TSOP-23 –40°C to 125°C
LT3467ES6 LT3467ES6#TR LTACH 6-Lead Plastic TSOP-23 –40°C to 85°C
LT3467AES67 LT3467AES6#TR LTBCC 6-Lead Plastic TSOP-23 –40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified 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 specifications, go to: http://www.linear.com/tapeandreel/
3
LT3467/LT3467A
3467afc
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
specifications from 0°C to 85°C. Specifications over the –40°C to 85°C
PARAMETER CONDITIONS MIN TYP MAX UNITS
Minimum Operating Voltage 2.2 2.4 V
Maximum Operating Voltage 16 V
Feedback Voltage 1.230 1.255 1.270 V
●1.220 1.280 V
FB Pin Bias Current (Note 3) ●10 50 nA
Quiescent Current V
SHDN
= 2.4V, Not Switching 1.2 2 mA
Quiescent Current in Shutdown V
SHDN
= 0.5V, V
IN
= 3V 0.01 1 μA
Reference Line Regulation 2.6V ≤ V
IN
≤ 16V 0.01 0.05 %/V
Switching Frequency LT3467 1 1.3 1.6 MHz
LT3467A 1.6 2.1 2.7 MHz
LT3467A ●1.6 MHz
Maximum Duty Cycle LT3467 88 94 %
LT3467 ●87 %
LT3467A 82 88 %
LT3467A ●78 %
Minimum Duty Cycle 10 %
Switch Current Limit At Minimum Duty Cycle 1.4 1.8 2.5 A
At Maximum Duty Cycle (Note 4) 0.8 1.2 1.9 A
Switch V
CESAT
I
SW
= 1.1A 330 500 mV
Switch Leakage Current V
SW
= 5V 0.01 1 μA
SHDN Input Voltage High 2.4 V
SHDN Input Voltage Low 0.5 V
SHDN Pin Bias Current V
SHDN
= 3V 16 32 μA
V
SHDN
= 0V 0 0.1 μA
SS Charging Current V
SS
= 0.5V 2 3 4.5 μA
The ● denotes specifications which apply over the full operating
temperature range, otherwise specifications are TA = 25°C. VIN = 3V, VSHDN = VIN unless otherwise noted. Specifications are for both
the LT3467 and LT3467A unless otherwise noted.
ELECTRICAL CHARACTERISTICS
operating temperature range are assured by design, characterization and
correlation with statistical process controls. LT3467IS6 is guaranteed and
tested over the full –40°C to 125°C operating temperature range.
Note 3: Current flows out of the pin.
Note 4: See Typical Performance Characteristics for guaranteed current
limit vs duty cycle.
4
LT3467/LT3467A
3467afc
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Quiescent Current vs
Temperature FB Pin Voltage vs Temperature SHDN Current vs SHDN Voltage
Current Limit vs Duty Cycle
Switch Saturation Voltage vs
Switch Current
Oscillator Frequency vs
Temperature
Soft-Start Current vs Soft-Start
Voltage
Start-Up Waveform
(Figure 2 Circuit)
Peak Switch Current vs Soft-Start
Voltage
I
Q
(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
V
FB
(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
V
SHDN
(V)
0
I
SHDN
(μA)
8
140
120
100
80
60
40
20
0
3467 G03
41612
210
61814
T
A
= 25°C
DC (%)
10
I
LIM
(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
T
A
= 25°C
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
V
SS
(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
T
A
= 25°C
V
CESAT
100mV
/DIV
SW CURRENT 200mA/DIV
T
A
= 85°C
T
A
= 25°C
T
A
= –40°C
3467 G05
V
SHDN
2V/DIV
V
OUT
1V/DIV
I
SUPPLY
0.5A/DIV
0.5ms/DIV
3467 G09
5
LT3467/LT3467A
3467afc
Figure 1. Block Diagram
–
+
–
+
RQ
S
0.01Ω
SW
DRIVER
COMPARATOR
SHDN
VIN
SS
FB
–
+
Σ
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
(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 V
OUT
= 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.
V
IN
(Pin 6/Pin 6): Input Supply Pin. Must be locally
bypassed.
SS (Pin 7/Pin 5): Soft-Start Pin. Place a soft-start capaci-
tor here. Upon start-up, 4μA of current charges the capaci-
tor to 1.255V. Use a larger capacitor for slower start-up.
Leave floating if not in use.
SHDN (Pin 8/Pin 4): Shutdown Pin. Tie to 2.4V or more to
enable device. Ground to shut down.
UU
U
PI FU CTIO S
BLOCK DIAGRA
W
6
LT3467/LT3467A
3467afc
OPERATIO
U
The LT3467 uses a constant frequency, current-mode
control scheme to provide excellent line and load regula-
tion. Refer to the Block Diagram above. 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 compara-
tor 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 amplifier A1, and is simply an amplified version of the
difference between the feedback voltage and the reference
voltage of 1.255V. In this manner, the error amplifier sets
the correct peak current level to keep the output in regu-
lation. If the error amplifier’s output increases, more
current is delivered to the output. Similarly, if the error
decreases, less current is delivered. The soft-start feature
APPLICATIONS INFORMATION
WUUU
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 compo-
nents 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
application is given by:
DC VVV
VVV
OUT D IN
OUT D CESAT
=+
+
||||–||
||||–| |
Where V
D
is the diode forward voltage drop and V
CESAT
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 conduc-
tion 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 suffice.
The LT3467A switches at 2.1MHz, allowing for even
smaller valued inductors to be used. 0.9μH to 6.8μH will
usually suffice. 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 I
2
R power
losses. Note that in some applications, the current han-
dling 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 efficiency,
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 1.3 MHz, (2.1MHz for the LT3467A) such as ferrite core.
7
LT3467/LT3467A
3467afc
APPLICATIONS INFORMATION
WUUU
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 startup. 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 startup.
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.
GND
V
IN
SW
SS FB
V
IN
2.6V TO
4.2V
D1
L1
2.7μH
R1
402k
LT3467
3467 TA05a
C2
15μF
C4
3.3pF
C1
4.7μF
R2
133k
V
OUT
5V
765mA AT V
IN
= 4.2V,
540mA AT V
IN
= 3.3V,
360mA AT V
IN
= 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)
Supply Current of Figure 2 During
Startup without Soft-Start Capacitor
V
OUT
1V/DIV
I
SUPPLY
0.5A/DIV
0.1ms/DIV
Supply Current of Figure 2 During
Startup with 47nF Soft-Start Capacitor
V
OUT
1V/DIV
I
SUPPLY
0.5A/DIV
0.5ms/DIV
8
LT3467/LT3467A
3467afc
APPLICATIONS INFORMATION
WUUU
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 sufficient for most applications, but systems
with very low output currents may need only a 1μF or 2.2μF
output capacitor. Solid tantalum or OSCON 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 sufficient 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
sufficient 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 OSCON) capacitors can affect
the stability of the overall system. The ESR of any capaci-
tor, along with the capacitance itself, contributes a zero to
the system. For the tantalum and OSCON capacitors, 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 V
OUT
and V
FB
as shown in Figure 2. The frequency
of the zero is determined by the following equation.
ƒ=
ZRC
1
214π••
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 capaci-
tor 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 efficiency, use a diode with
better thermal characteristics such as the On Semicon-
ductor MBRM120 (a 20V diode) or the MBRM140 (a 40V
diode).
9
LT3467/LT3467A
3467afc
APPLICATIONS INFORMATION
WUUU
SETTING OUTPUT VOLTAGE
To set the output voltage, select the values of R1 and R2
(see Figure 2) according to the following equation.
RR V
V
OUT
12
1 255 1=⎛
⎝
⎜⎞
⎠
⎟
.–
A good value for R2 is 13.3k which sets the current in the
resistor divider chain to 1.255V/13.3k = 94μA.
Figure 3. Transient Response of Figure 8's Step-Up
Converter without Phase Lead Capacitor
LOAD CURRENT
100mA/DIV
AC COUPLED
VOUT
200mV/DIV
AC COUPLED
20μs/DIV 3467 F03
IL1
5A/DIV
AC COUPLED
Figure 4. Transient Response of Figure 8's Step-Up
Converter with 22pF Phase Lead Capacitor
20μs/DIV 3467 F04
LOAD CURRENT
100mA/DIV
AC COUPLED
VOUT
200mV/DIV
AC COUPLED
IL1
5A/DIV
AC COUPLED
LAYOUT HINTS
The high speed operation of the LT3467/LT3467A de-
mands careful attention to board layout. You will not get
advertised 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
VIA’s under the exposed PAD. These should connect to a
local ground plane for better thermal performance.
Figure 5A.
Suggested Layout—ThinSOT
R2
R1
GND
C2
C3
L1
D1 C1
V
OUT
V
OUT
V
IN
SHDN
3467 F05A
FB
C
SS
SS
1
2
3
6
5
4
Figure 5B.
Suggested Layout—DFN
R2
R1
GND
C2
C1
L1
D1
V
OUT
V
OUT
3467 F05B
C3
FB
C
SS
V
IN
1
2
3
4
8
7
6
5
SHDN
10
LT3467/LT3467A
3467afc
APPLICATIONS INFORMATION
WUUU
Compensation—Theory
Like all other current mode switching regulators, the
LT3467/LT3467A needs to be compensated for stable and
efficient 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
replaced by the equivalent transconductance amplifier g
mp
.
g
mp
acts as a current source where the output current is
proportional to the V
C
voltage. Note that the maximum output
current of g
mp
is finite due to the current limit in the IC.
–
+
–
+
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
Output Pole: P1= 2
Error Amp Pole:
L
2• • •πRC
OUT
P2= 1
Error Amp Zero: Z1= 1
O
C
2
2
•• •
•• •
π
π
RC
RC
C
CC
OUT
IN mp
VVgDC GAIN: A= 1.255 gR R
ma O L
2
1
•• •• ••
22
21
2
ESR Zero:
RHP Zero: Z3=
ZRC
V
ESR OUT
=π•• •
IIN L
OUT
R
VL
f
2
2
2
•
•• •π
High Frequency Pole: P3>
SS
PL
Phase Lead Zero Z RC
Phase Lead Pol
3
41
21
:•• •
=π
eeP
CRR
RR
PL
:
•• • •
41
212
12
=
+
π
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.
From Figure 6, the DC gain, poles and zeroes can be
calculated as follows:
11
LT3467/LT3467A
3467afc
APPLICATIONS INFORMATION
WUUU
Figure 7.Bode Plot of 3.3V to 5V Application
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
Table 3. Bode Plot Parameters
Parameter Value Units Comment
R
L
10.4 ΩApplication Specific
C
OUT
15 μF Application Specific
R
ESR
10 mΩApplication Specific
R
O
0.4 MΩNot Adjustable
C
C
60 pF Not Adjustable
C
PL
3.3 pF Adjustable
R
C
100 kΩNot Adjustable
R1 402 kΩAdjustable
R2 133 kΩAdjustable
V
OUT
5 V Application Specific
V
IN
3.3 V Application Specific
g
ma
35 μmho Not Adjustable
g
mp
7.5 mho Not Adjustable
L 2.7 μH Application Specific
f
S
1.3* 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.
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
Lithium-Ion to 6V Step-Up DC/DC Converter
I
OUT
(mA)
EFFICIENCY (%)
200
95
90
85
80
75
70
65
60
55
50
3467 TA02b
10050 300 400 500 600 700
V
IN
= 3.8V
V
IN
= 4.2V
V
IN
= 2.7V
Li-Ion to 6V
TYPICAL APPLICATIO S
U
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.
12
LT3467/LT3467A
3467afc
TYPICAL APPLICATIO S
U
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
2.2μFR3
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
±15V Dual Output Converter with Output Disconnect
GND
V
IN
SW
SHDN
FB
V
IN
5V
D1
L1
2.7μH
R1
412k
LT3467
3467 TA04a
C2
1μF
C1
4.7μF
C3
0.1μF
R2
13.3k
V
OUT
40V
20mA
C1: X5R or X7R, 6.3V
C2: X5R or X7R, 50V
D1: ON SEMICONDUCTOR, MBRM140
L1: SUMIDA CD43-2R7
SHDN
SS
5V to 40V Boost Converter
GND
V
IN
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
V
OUT
5V
325mA AT V
IN
= 4V
400mA AT V
IN
= 5V
450mA AT V
IN
= 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
4-Cell to 5V SEPIC Converter
13
LT3467/LT3467A
3467afc
TYPICAL APPLICATIO S
U
8V, 23V, –8V Triple Output TFT-LCD Bias Supply with Soft-Start
GND
V
IN
SW
SS FB
V
IN
3.3V
D7
L1
4.7μH
R1
113k
LT3467
3467 TA08a
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
V
SHDN
Start-Up Waveforms
8V OUTPUT
5V/DIV
–8V OUTPUT
5V/DIV
23V OUTPUT
10V/DIV
IL1 0.5A/DIV
2ms/DIV
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 TA07a
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
Start-Up Waveforms
9V OUTPUT
5V/DIV
–9V OUTPUT
5V/DIV
18V OUTPUT
10V/DIV
IL1 0.5A/DIV
2ms/DIV
14
LT3467/LT3467A
3467afc
TYPICAL APPLICATIO S
U
I
OUT
(mA)
EFFICIENCY (%)
90
85
80
75
70
65
60
55
50 400
3467 TA08b
10050 150 250 350 450
200 300 500
V
IN
= 3.3V
V
IN
= 2.6V
Efficiency
GND
VIN SW
SHDN
FB
VIN
2.6V
TO 3.3V
D1
L1
1.5μH
R1
8.06k
LT3467A
3467 TA09a
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
2.6V – 3.3V to 5V Boost Converter
I
OUT
(mA)
EFFICIENCY (%)
95
90
85
80
75
70
65
60
55
50 400
3467 TA09b
10050 150 250 350 450
200 300 500
V
IN
= 3.3V
V
IN
= 4.2V
V
IN
= 2.6V
Efficiency
GND
V
IN
SW
SHDN
FB
V
IN
2.6V
TO 4.2V
D1
L1
0.9μH
R1
8.06k
LT3467A
3467 TA10a
C2*
22μF
C4*
75pF
C1
4.7μF
R2
2.67k
V
OUT
5V
600mA AT V
IN
= 4.2V
360mA AT V
IN
= 3.3V
250mA AT V
IN
= 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
Single Li-Ion Cell to 5V Boost Converter
IOUT (mA)
EFFICIENCY (%)
3467 TA10b
90
80
70
60
50
40
30 40 80 100
20 60 120 140 160
Efficiency
GND
V
IN
SW
SHDN
FB
V
IN
3.3V
D1
L1
6.8μH
R1
16.5k
LT3467A
3467 TA11a
C2
2.2μF
C4
68pF
C1
4.7μF
R2
1.5k
V
OUT
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
3.3V to 15V, 135mA Step-Up Converter
15
LT3467/LT3467A
3467afc
U
PACKAGE DESCRIPTIO
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-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
2.00 ±0.10
(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 ± 0.10
BOTTOM VIEW—EXPOSED PAD
0.56 ± 0.05
(2 SIDES)
0.75 ±0.05
R = 0.115
TYP
R = 0.05
TYP
2.15 ±0.05
(2 SIDES)
3.00 ±0.10
(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 ± 0.05
2.20 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
0.61 ±0.05
(2 SIDES)
1.15 ±0.05
0.70 ±0.05
2.55 ±0.05
PACKAGE
OUTLINE
0.25 ± 0.05
0.50 BSC
PIN 1
R = 0.20 OR
0.25 × 45°
CHAMFER
0.50 BSC
DDB Package
8-Lead Plastic DFN (3mm × 2mm)
(Reference LTC DWG # 05-08-1702 Rev B)
S6 Package
6-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1636)
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
16
LT3467/LT3467A
3467afc
LT 0707 REV C • PRINTED IN USA
© LINEAR TECHNOLOGY CORPORATION 2003
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507
●
www.linear.com
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Figure 8. 5V to 12V, 270mA Step-Up Converter
GND
V
IN
SW
SS FB
V
IN
5V
D1
L1
4.7μH
R1
115k
LT3467
3467 TA06a
C2
10μF
C4*
22pF
C1
2.2μF
C3
0.047μFR2
13.3k
V
OUT
12V
270mA
C1: X5R OR X7R, 6.3V
C2: X5R OR X7R, 16V
D1: PHILIPS PMEG 2010
L1: SUMIDA CR43-4R7
*OPTIONAL
SHDNSHDN
I
OUT
(mA)
50
EFFICIENCY (%)
100 250200150 300 350
3467 TA06b
90
85
80
75
70
65
60
55
50
Efficiency
TYPICAL APPLICATIO S
U
GND
VIN SW
SHDN
FB
VIN
5V
D1
L1
3.3μH
R1
115k
LT3467A
3467 TA12a
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
Efficiency
IOUT (mA)
EFFICIENCY (%)
200
95
90
85
80
75
70
65
60
55
50
3467 TA12b
10050 150 250 300
