LT3479
1
3479fc
TYPICAL APPLICATION
DESCRIPTION
3A, Full Featured DC/DC
Converter with Soft-Start
and Inrush Current Protection
The LT
®
3479 is a current mode, fi xed frequency step-up
DC/DC converter with an internal 3A, 42V switch. Effi cien-
cies of up to 89% can be achieved in typical applications. It
features a programmable soft-start function to limit induc-
tor current during start-up and inrush current protection
to protect the LT3479 during shorts and line transients.
Both inputs of the error amplifi er are available to the user
allowing positive and negative output voltages. Through
an external resistor, the user can program the switch-
ing frequency from 200kHz to 3.5MHz. The low profi le
(0.75mm) 14-pin, 4mm × 3mm DFN package provides
excellent thermal performance in a small footprint. The
LT3479 is also available in a thermally enhanced 16-pin
TSSOP package.
5V to 12V Boost Converter
FEATURES
APPLICATIONS
n High Power LED Driver
n DSL Modems
n Distributed Power
n Wide Input Voltage Range: 2.5V to 24V
n 3A, 42V Internal Switch
n High Effi ciency Power Conversion: Up to 89%
n Soft-Start
n Frequency Set by External Resistor: 200kHz to
3.5MHz
n Protection Against Input Short Circuits and
Hot Plugging
n Low VCESAT Switch: 0.3V at 2.5A (Typical)
n Capable of Positive and Negative Outputs
n Available in Thermally Enhanced 14-Lead
(4mm × 3mm) DFN and 16-Lead TSSOP Packages
5V to 12V Effi ciency
200k
23.2k
17.8k 10k
2.2μF
VIN
5V
4.7μH
3479 TA01
FBN
SWLVS
VIN
VC
GNDRT
VREF
SHDN
SS
LT3479
FBP
2.2nF
10μF
VOUT
12V
0.8A
10nF
IOUT (A)
0
EFFICIENCY (%)
70
80
0.8
3479 TA02
60 0.2 0.4 0.6
90
65
75
85
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
LT3479
2
3479fc
ABSOLUTE MAXIMUM RATINGS
SW, L, VS Voltages ................................................... 42V
VIN, SHDN Voltages ................................................. 24V
FBP, FBN, VREF, RT, VC Voltages ................................. 2V
Junction Temperature .......................................... 125°C
(Note 1)
14
13
12
11
10
9
8
1
2
3
4
5
6
7
GND
GND
SS
VC
FBN
FBP
VREF
SW
SW
L
VS
VIN
RT
SHDN
TOP VIEW
15
DE14 PACKAGE
14-LEAD (4mm s 3mm) PLASTIC DFN
TJMAX = 125°C, θJA = 43°C/W
EXPOSED PAD (PIN 15) IS PGND (MUST BE SOLDERED TO PCB)
FE PACKAGE
16-LEAD PLASTIC TSSOP
1
2
3
4
5
6
7
8
TOP VIEW
16
15
14
13
12
11
10
9
SW
SW
L
VS
VIN
RT
SHDN
GND
GND
GND
GND
SS
VC
FBN
FBP
VREF
17
TJMAX = 125°C, θJA = 38°C/W
EXPOSED PAD (PIN 17) IS PGND (MUST BE SOLDERED TO PCB)
PIN CONFIGURATION
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LT3479EDE#PBF LT3479EDE#TRPBF 3479 14-Lead (4mm × 3mm) Plastic DFN –40°C to 85°C
LT3479EFE#PBF LT3479EFE#TRPBF 3479EFE 16-Lead Plastic TSSOP –40°C to 85°C
LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LT3479EDE LT3479EDE#TR 3479 14-Lead (4mm × 3mm) Plastic DFN –40°C to 85°C
LT3479EFE LT3479EFE#TR 3479EFE 16-Lead Plastic TSSOP –40°C to 85°C
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges.
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/
Operating Temperature Range (Note 2).... –40°C to 85°C
Storage Temperature Range ................... –65°C to 125°C
Lead Temperature (Soldering, 10 sec)
TSSOP .............................................................. 300°C
LT3479
3
3479fc
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 LT3479 is guaranteed to meet performance specifi cations
from 0°C to 70°C. Specifi cations over the –40°C to 85°C operating
PARAMETER CONDITIONS MIN TYP MAX UNITS
Minimum Input Voltage l2.3 2.5 V
Quiescent Current VIN = 2.5V, VSHDN = 0V
VIN = 2.5V, VSHDN = 2.5V, VC = 0.3V (Not Switching)
0.1
5
1
7.5
μA
mA
Reference Voltage Measured at VREF Pin l1.216 1.235 1.250 V
Reference Voltage Line Regulation 2.5V < VIN < 24V, VC = 0.3V 0.01 0.03 %/V
Maximum VREF Pin Current Out of Pin 100 μA
Soft-Start Pin Current SS = 0.5V, Out of Pin 9 μA
FBP Pin Bias Current 25 100 nA
FBN Pin Bias Current 25 100 nA
Feedback Amplifi er Offset Voltage FBP – FBN, VC = 1V –2 2 6 mV
Feedback Amplifi er Voltage Gain 250 V/V
Feedback Amplifi er Transconductance 150 μS
Feedback Amplifi er Sink Current VFBP = 1.25V, VFBN = 1.5V, VC = 0.5V 10 μA
Feedback Amplifi er Source Current VFBP = 1.25V, VFBN = 1V, VC = 0.5V 10 μA
Switching Frequency RT = 17.8k
RT = 113k
RT = 1.78k
0.9
160
2.7
1
200
3.5
1.15
240
4.1
MHz
kHz
MHz
Maximum Switch Duty Cycle RT = 17.8k l84 93 %
SHDN Pin Current VSHDN = 5V
VSHDN = 0V
30
0.1
60
1
μA
μA
SHDN Pin Threshold 0.3 1.5 2 V
Inductor Current Limit (Note 3) 3.5 5 6.5 A
Switch Current Limit (Note 3) 3 4.5 6 A
Switch VCESAT ISW = 1A (Note 3) 120 200 mV
Switch Leakage Current SW = 40V 0.2 5 μA
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at TA = 25°C. VIN = 2.5V, VSHDN = 2.5V.
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 3: Inductor Current Limit, Switch Current Limit and Switch VCESAT for
DE package guaranteed by design and/or correlation to static test.
LT3479
4
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TYPICAL PERFORMANCE CHARACTERISTICS
SWITCH CURRENT (A)
0
0
VCE(SAT) (V)
0.1
0.2
0.3
125°C
–50°C
0.5
0.4
0.5 1 1.5 2
3479 G01
2.5 3
25°C
TEMPERATURE (°C)
–50
CURRENT (A)
4
5
6
25 75
3479 G02
3
2
–25 0 50 100 125
1
0
INDUCTOR CURRENT LIMIT
SWITCH CURRENT LIMIT
TEMPERATURE (°C)
–50
1.21
VREF (V)
1.22
1.23
1.24
1.26
1.25
1.27
–25 0 25 50
3479 G03
75 125100 150
VIN = 24V
VIN = 2.5V
TEMPERATURE (°C)
–50
1.250
SHDN THRESHOLD (V)
1.375
1.500
1.625
1.750
–25 0 25 50
3479 G04
75 100 125
VSHDN (V)
0
0
SHDN PIN CURRENT (μA)
10
20
30
40
50
481216
3479 G05
20 24
–50°C
25°C
125°C
TEMPERATURE (°C)
–50
2
VIN PIN CURRENT (mA)
3
4
5
6
–25 0 25 50
3479 G06
75 125100 150
VC = 0.3V
TEMPERATURE (°C)
–50
0
ISS (μA)
5
10
15
20
–25 0 25 50
3479 G07
75 125100 150
TEMPERATURE (°C)
–50
0
FREQUENCY (MHz)
0.4
0.8
1.2
1.6
2.0
–25 0 25 50
3479 G08
75 125100 150
RT = 10k
RT = 15k
RT = 20k
TEMPERATURE (oC)
–50
0
OFFSET VOLTAGE (mV)
1
2
3
4
5
–25 02550
3479 G09
75 100
VC = 0.5V
VC = 1V
SHDN Pin Turn-On Threshold SHDN Pin Current VIN Pin Current
Soft-Start Pin Current Oscillator Frequency Feedback Amplifi er Offset Voltage
Switch VCE(SAT) Inductor and Switch Current Limit VREF
LT3479
5
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PIN FUNCTIONS
SW (Pins 1, 2/Pins 1, 2): Switch Pins. Collector of the
internal NPN power switch. Connect the inductor and diode
here and minimize the metal trace area connected to this
pin to minimize electromagnetic interference.
L (Pin 3/Pin 3): Inductor Pin. Connect the inductor to
this pin.
VS (Pin 4/Pin 4): Inductor Supply. Must be locally bypassed.
Powers the switch and the inductor. In case only one supply
voltage is available, tie VIN and VS together.
VIN (Pin 5/Pin 5): Input Supply. Must be locally bypassed.
Powers the internal control circuitry.
RT (Pin 6/Pin 6): Timing Resistor Pin. Adjusts the switch-
ing frequency. Do not leave this pin open. See Table 4 for
RT values and switching frequencies.
SHDN (Pin 7/Pin 7): Shutdown. Tie to 1.5V or greater to
enable the device. Tie below 0.3V to turn off the device.
VREF (Pin 8/Pin 9): Bandgap Voltage Reference. Internally
set to 1.235V. Connect this pin to FBP if generating a posi-
tive output, or to an external resistor divider if generating a
negative voltage. This pin can provide up to 100μA of current
and can be locally bypassed with a 100pF capacitor.
FBP (Pin 9/Pin 10): The Noninverting Input to the Error
Amplifi er. Connect resistive divider tap here for negative
output voltage.
FBN (Pin 10/Pin 11): The Inverting Input to the Error
Amplifi er. Connect resistive divider tap here for positive
output voltage.
VC (Pin 11/Pin 12): Compensation Pin for Error Amplifi er.
Connect a series RC from this pin to GND. Typical values
are 10kΩ and 2.2nF.
SS (Pin 12/Pin 13): Soft-Start. Place a soft-start capacitor
here. Leave fl oating if not in use.
GND (Pins 13, 14/Pins 8, 14, 15, 16): Ground. Tie directly
to local ground plane.
Exposed Pad (Pin 15/Pin 17): Power Ground. Must be
connected to electrical PCB ground.
(DFN/TSSOP)
LT3479
6
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BLOCK DIAGRAM
+
+
+
+
+
3
CSS
CIN
CCCSC1
R1
FB
LSW
D1
L1
RC
R2
8.5mW
FBP
FBN
SHDN
VREF
VIN
RT
RT
VC
VS
ICON
SLOPE
SS
FEEDBACK
AMPLIFIER
PWM
COMPARATOR
CURRENT LIMIT
COMPARATOR
INRUSH CURRENT
PROTECTION
COMPARATOR
MASTER
LATCH DRIVER
GND
Q1
3479 BD
pwmout
36mV
OSCILLATOR
RQ
S
t
t
1.25V
REFERENCE
LT3479
7
3479fc
OPERATION
The LT3479 uses a fi xed frequency, current mode control
scheme to provide excellent line and load regulation. Op-
eration can be best understood by referring to the Block
Diagram. The start of each oscillator cycle sets the SR latch
and turns on power switch Q1. The signal at the inverting
input of the PWM comparator (SLOPE) is proportional to
the sum of the switch current and oscillator ramp. When
SLOPE exceeds VC (the output of the feedback amplifi er),
the PWM comparator resets the latch and turns off the
power switch. In this manner, the feedback amplifi er and
PWM comparators set the correct peak current level to
keep the output in regulation.
The LT3479 also features a soft-start function. During
start-up, 10μA of current charges the external soft-start
capacitor. The SS pin directly limits the rate of voltage rise
on the VC pin, which in turn limits the peak switch cur-
rent. The switch current is constantly monitored and not
allowed to exceed the nominal value of 3A. If the switch
current reaches 3A, the SR latch is reset regardless of the
output of the PWM comparator. Current limit protects the
power switch and external components.
Soft-start plays an important role in applications where the
switch will reach levels of 30V or higher. During startup,
an overshoot in the switch current together with the pres-
ence of high switch voltage can overstress the switch. A
properly used soft-start feature will greatly improve the
robustness of such designs.
In addition to soft-start, inrush current protection protects
the LT3479 against shorts and line transients. During such
faults, the inductor current can momentarily exceed 3A and
damage the switch. Through an internal 8.5mΩ resistor
placed in series with the inductor, the inrush current protec-
tion comparator measures the inductor current. If it exceeds
5A, a soft-start cycle is initiated. The LT3479 will remain in
the soft-start condition until the fault has passed.
LT3479
8
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Capacitor Selection
Low ESR (equivalent series resistance) ceramic capaci-
tors should be used at the output to minimize the output
ripple voltage. Use only X5R or X7R dielectrics, as these
materials retain their capacitance over wider voltage and
temperature ranges better than other dielectrics. A 4.7μF
to 10μF output capacitor is suffi cient for most high output
current designs. Converters with lower output currents
may need only a 1μF or 2.2μF output capacitor.
Table 1. Ceramic Capacitor Manufacturers
MANUFACTURER PHONE WEB
Taiyo Yuden (408) 573-4150 www.t-yuden.com
AVX (803) 448-9411 www.avxcorp.com
Murata (714) 852-2001 www.murata.com
Inductor Selection
Several inductors that work well with the LT3479 are listed
in Table 2. However, there are many other manufacturers
and devices that can be used. Consult each manufacturer
for more detailed information and their entire range of
parts. Ferrite core inductors should be used to obtain the
best effi ciency. Choose an inductor that can handle the
necessary peak current without saturating, and ensure
that the inductor has a low DCR (copper-wire resistance)
to minimize I2R power losses. A 4.7μH or 10μH inductor
will suffi ce for most LT3479 applications.
Inductor manufacturers specify the maximum current
rating as the current where the inductance falls to some
percentage of its nominal value—typically 65%. An inductor
APPLICATIONS INFORMATION
Table 2. Suggested Inductors
MANUFACTURER
PART NUMBER
IDC
(A)
INDUCTANCE
(μH)
MAX DCR
(mΩ)
L × W × H
(mm) MANUFACTURER
CDRH6D283R0
CDRH6D28100
CDRH4D284R7
3
1.7
1.32
3
10
4.7
24
65
72
6.7 × 6.7 × 3.0
6.7 × 6.7 × 3.0
5.0 × 5.0 × 3.0
Sumida
www.sumida.com
LM N 05D B4R7M
LM N 05D B100K
2.2
1.6
4.7
10
49
10
5.9 × 6.1 × 2.8
5.9 × 6.1 × 2.8
Taiyo Yuden
www.t-yuden.com
LQH55DN4R7M01L
LQH55DN100M01K
2.7
1.7
4.7
10
57
130
5.7 × 5.0 × 4.7
5.7 × 5.0 × 4.7
Murata
www.murata.com
FDV0630-4R7M 4.2 4.7 49 7.0 × 7.7 × 3.0 Toko
www.toko.com
Figure 1. Effi ciency vs Inductor Size
IOUT (A)
0
EFFICIENCY (%)
70
80
0.8
3479 F01
60
50 0.2 0.4 0.6
90
65
75
55
85
SUMIDA CDRH4D28-4R7
TOKO FDV0630-4R7
can pass a current larger than its rated value without
damaging it. Aggressive designs where board space is
precious will exceed the maximum current rating of the
inductor to save board space. Consult each manufacturer
to determine how the maximum inductor current is
measured and how much more current the inductor can
reliably conduct.
Physically larger inductors provide better effi ciency than
smaller ones. Figure 1 shows a 3% to 4% effi ciency gain
in using a larger inductor in a 1MHz, 5V to 12V application.
The effi ciency of the TOKO FDV0630-4R7M, which mea-
sures 7mm × 7.7mm and 3 mm thick, peaks at 87%. The
smaller Sumida CDRH4D28-4R7 which is 5mm × 5mm and
3mm thick yields a peak effi ciency of 85% in an identical
application. Thus, if board space is abundant, then larger
inductors should be used to maximize effi ciency.
LT3479
9
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Setting Negative Output Voltages
To set a negative output voltage, select the values of R3 and
R4 (see Figure 3) according to the following equation:
VV
R
R
OUT =
–.1 235 3
4
Figure 2. Positive Output Voltage Feedback Connections
R2
R1
3479 F02
FBN
VREF
VOUT
LT3479
FBP
Figure 3. Negative Output Voltage Feedback Connections
R4
R3
3479 F03
FBP
VREF
–VOUT
LT3479
FBN
APPLICATIONS INFORMATION
Diode Selection
Schottky diodes, with their low forward voltage drop and
fast switching speed, are ideal for LT3479 applications.
Table 3 lists several Schottky diodes that work well with the
LT3479. The diode’s average current rating must exceed
the average output current. The diode’s maximum reverse
voltage must exceed the output voltage. The diode conducts
current only when the power switch is turned off (typically
less than 50% duty cycle), so a 3A diode is suffi cient for
most designs. The companies below also offer Schottky
diodes with high voltage and current ratings.
Table 3. Suggested Diodes
MANUFACTURER
PART NUMBER
MAX
CURRENT (A)
MAX REVERSE
VOLTAGE (V) MANUFACTURER
UPS340
UPS315
3
3
40
15
Microsemi
www.microsemi.com
B220
B230
B240
B320
B330
B340
SBM340
2
2
2
3
3
3
3
20
30
40
20
30
40
40
Diodes, Inc
www.diodes.com
Setting Positive Output Voltages
To set a positive output voltage, select the values of R1 and
R2 (see Figure 2) according to the following equation:
VV
R
R
OUT =+
1 235 1 1
2
.
Board Layout
As with all switching regulators, careful attention must
be paid to the PCB board layout and component place-
ment. To maximize effi ciency, switch rise and fall times
are made as short as possible. To prevent radiation and
high frequency resonance problems, proper layout of the
high frequency switching path is essential. Minimize the
length and area of all traces connected to the SW pin and
always use a ground plane under the switching regulator
to minimize interplane coupling. The signal path including
the switch, output diode D1 and output capacitor COUT,
contains nanosecond rise and fall times and should be
kept as short as possible. Recommended component
placement is shown in Figure 4.
Soft-Start
For many applications, it is necessary to minimize the
inrush current at start-up. The built-in soft-start circuit
signifi cantly reduces the start-up current spike and output
voltage overshoot. A typical value is 10nF for 1.65ms.
Figure 5 shows the start-up output voltage and induc-
tor current waveforms in a typical application without a
soft-start capacitor. Notice the output voltage overshoot
and the large initial current. The addition of a 22nF capaci-
tor eliminates the output overshoot and reduces the peak
inductor current (Figure 6).
LT3479
10
3479fc
APPLICATIONS INFORMATION
GND
GND
SS
VC
FBN
FBP
VREF
SW
SW
L
VS
VIN
RT
SHDN
LT3479
RT
R2
CSS RC
R1
CC
COUT
D
CIN
CS
L1
MINIMIZE THE AREA
OF THIS TRACE
TO VS
TO VIN
TO GND
TO SHDN
3479 F04
PLACE VIAS AROUND EXPOSED PAD
TO ENHANCE THERMAL PERFORMANCE
TO VOUT
Figure 4. Suggested Board Layout
Switching Frequency
The switching frequency of the LT3479 is set by an exter-
nal resistor attached to the RT pin. Do not leave this pin
open. A resistor must always be connected for proper
operation. See Table 4 and Figure 7 for resistor values
and corresponding frequencies.
Table 4. Switching Frequency
SWITCHING FREQUENCY (MHz) RT (kΩ)
3.5 1.78
3 2.87
2.5 4.32
2 6.49
1.5 10.2
1 17.8
0.5 39.2
0.2 113
Figure 5. Start-Up with No Soft-Start Capacitor
0.2MS/DIV
IL
2A/DIV
VOUT
5V/DIV
3479 F05
Figure 6. Start-Up with CSS = 22nF
0.2ms/DIV
IL
2A/DIV
VOUT
5V/DIV
3479 F06
LT3479
11
3479fc
Increasing switching frequency reduces output voltage
ripple but also reduces effi ciency. The user should set
the frequency for the maximum tolerable output voltage
ripple. Figure 8 shows a reduction in effi ciency of about
4% between 1MHz and 2MHz operation in a typical
application.
Inrush Current Protection
The LT3479 features a novel inductor current sensing
circuit that protects the LT3479 during hot plugging and
short circuits. An internal resistor in series with the ex-
ternal inductor senses the inductor current at all times.
When it exceeds 5A, a soft-start cycle is initiated. Figure 9
APPLICATIONS INFORMATION
shows an output overload with inrush current protection
disabled. Notice that soft-start remains high, and that
the inductor current does not return to zero. Figure 10
illustrates the benefi ts of inrush current protection. The
output short initiates a new soft start cycle reducing the
inductor current. After the fault has passed, the inductor
current slowly returns to its equilibrium value. To ensure
bond wire integrity, the inductor current should not exceed
8A for more than 10ms.
Bypassing the 8.5mΩ inductor current sense resistor
disables inrush current protection. Connect the inductor
supply trace and bypass capacitor to the L pin and leave
the VS pin open to disable this feature.
Figure 7. Switching Frequency
RT (kΩ)
0
1.5
1.0
0.5
3.5
3.0
2.5
2.0
3479 F07
SWITCH FREQUENCY (MHz)
0.1 100
10
Figure 8. Effi ciency vs Switching Frequency
IOUT (A)
0
EFFICIENCY (%)
70
80
1MHz
0.8
3479 F08
60
50
0.2 0.4 0.6
90
65
75
55
85
2MHz
20μs/DIV
VSW
10V/DIV
IL
4V/DIV
VSS
2V/DIV
VOUT
20V/DIV
3479 F09
Figure 9. Output Overload with
Inrush Current Protection Enabled
20μs/DIV
VSW
10V/DIV
IL
4V/DIV
VSS
2V/DIV
VOUT
20V/DIV
3479 F10
Figure 10. Output Overload with
Inrush Current Protection Disabled
Figure 11. Circuit for Output Overload
LT3479
BOOST
REGULATOR
VIN
0.5Ω
3479 F11
VOUT
LT3479
12
3479fc
TYPICAL APPLICATIONS
200k
23.2k
17.8k 10k
C1
2.2μF
VIN
5V
D1
L1
4.7μH
3479 TA03
FBN
SWLVS
VIN
VC
GNDRT
VREF
SHDN
SS
LT3479
FBP
2.2nF
C1: TAIYO YUDEN LMK316BJ225MD
C2: AVX 1206 YD106MAT
D1: DIODES INC B320A
L1: TOKO FDV0630-4R7M
C2
10μF
VOUT
12V
0.8A
10nF
5V to 12V/800mA 1MHz Boost Converter
IOUT (A)
0
EFFICIENCY (%)
70
80
0.8
3479 TA03b
60
50 0.2 0.4 0.6
90
65
75
55
85
Effi ciency
200k
23.2k
39.2k 4.7k
C1
2.2μF
VIN
5V
D1
L1
10μH
3479 TA04
FBN
SWLVS
VIN
VC
GNDRT
VREF
SHDN
SS
LT3479
FBP
10nF
C1: TAIYO YUDEN LMK316BJ225MD
C2: AVX 1206 YD106MAT
D1: DIODES INC. B320A
L1: SUMIDA CDRH8D43-100
C2
10μF
VOUT
12V
0.8A
10nF
5V to 12V/800mA 500kHz Boost Converter
IOUT (A)
0
EFFICIENCY (%)
70
80
0.8
3479 TA04b
60
50
0.2 0.4 0.6
90
65
75
55
85
Effi ciency
LT3479
13
3479fc
TYPICAL APPLICATIONS
169k
30.9k
17.8k 4.3k
C1
2.2μF
VIN
3.3V
D1
L1
4.7μH
3479 TA05
FBN
SWLVS
VIN
VC
GNDRT
VREF
SHDN
SS
LT3479
FBP
10nF
C1: TAIYO YUDEN LMK316BJ225MD
C2: AVX 1206 YD106MAT
D1: DIODES INC B320A
L1: TOKO FDV0630-4R7M
C2
10μF
VOU
8V
0.9
A
10nF
3.3V to 8V/900mA Boost Converter
IOUT (A)
0
EFFICIENCY (%)
70
80
0.8
3479 TA03b
60
50 0.2 0.4 0.6
90
65
75
55
85
Effi ciency
100k
402k
17.8k 1k
C1
2.2μF
VIN
5V
100pF
D1
D3
D2
C2
2.2μF
L1
4.7μH
3479 TA06
15nF
C1, C2: TAIYO YUDEN LMK316BJ225MD
C3: AVX 1206 YD106MAT
D1, D2: DIODES INC B320A
D3: CENTRAL SEMI, CMDSH-3-LTC
L1: TOKO FDV0630-4R7M
C3
10μF
VOUT
–5V
600mA
10nF
FBP
SWLVS
VIN
VC
GNDRT
VREF
SHDN
SS
LT3479
FBN
5V to –5V/600mA Inverting DC/DC Converter
IOUT (A)
0
EFFICIENCY (%)
70
80
0.8
3479 TA04b
60
50
0.2 0.4 0.6
90
65
75
55
85
Effi ciency
LT3479
14
3479fc
TYPICAL APPLICATIONS
C2
2.2μF
0.15Ω
ON
3479 TA07
600mA
L1
4.7μH D1
VIN
2.8V TO 4.2V
10k
124k
7.5k 10k
2.2nF
C1, C2: TAIYO YUDEN LMK316BJ225MD
D1: PHILIPS PMEG 2010
D2, D3: LUMILEDS LXHL-PW01
L1: SUMIDA CDRH4D28-4R7
M1: VISHAY SILICONIX Si2302ADS
10nF
C1
2.2μF
FBN
SWLVS
VIN
VREF
SHDNON
M1
SS LT3479
FBP
VC
RTGND
D2
D3
500mA, 12 White LED Driver
LT3479
15
3479fc
TYPICAL APPLICATIONS
C2
4.7μF
ILED
500mA 0.150Ω
3479 TA08
L1
10μH D1
VIN
8V TO 16V
93.1k
5.9k
100k
17.8k 10k
3.3nF
C1: TAIYO YUDEN EMK316BJ475ML
C2: TAIYO YUDEN TMK325BJ475ML
D1: DIODES INC B330B
D2: LUMILEDS LXHL-NW99
L1: SUMIDA CDRH8D28-100
10nF
C1
4.7μF
FBN
D2
SWLVS
VIN
VREF
SHDN
SS LT3479
FBP
VC
RTGND
VOUT
16V TO 24V
500mA, 12 White LED Driver
IOUT (A)
0
EFFICIENCY (%)
0.5
3479 TA08b
0.1 0.2 0.3 0.4
100
90
80
70
60
50
VIN = 8V
VIN = 12V VIN = 16V
Effi ciency
LT3479
16
3479fc
TYPICAL APPLICATIONS
100k
18.7k
17.8k 10k
C1
4.7μF
C6
0.1μF
C5
0.1μF
VIN
2.8V TO 4.2V
L1
3.3μH
3479 TA10
FBN
SWLVS
VIN
VC
GNDRT
VREF
SHDN
SS
LT3479
FBP
2.2nF
C2
22μF
8V
700mA
–8V
10mA
16V
10mA
C4
F
C3
F
10nF
D2A
D1
D2B
D3B
D3A
C1: AVX 0805ZD475MAT
C2: AVX 1210YD226MAT
C3 TO C6: X5R/X7R 10V
D1: MBRM120 OR EQUIVALENT
D2, D3: BAT54S OR EQUIVALENT
L1: SUMIDA CDRH4D28-3R3
8V, 16V, –8V Triple Output Power Supply for TFTLCD Panels
LOAD CURRENT (A)
0
EFFICIENCY (%)
100
90
80
70
60
50
0.2 0.4 0.5
3479 TA10b
0.1 0.3 0.6 0.7
Effi ciency
LT3479
17
3479fc
TYPICAL APPLICATIONS
3479 TA11
L3
15μH
10.2k
1.13k
11.3k
10.2k 4.99k
3.3nF
D1, D2: DIODES INC DFLS230 2A, 30V
D3: PHILIPS 1PS79SB62
L1-L4: SUMIDA CDRH6D38-150
ALL CAPACITORS X5R/X7R DIELECTRIC
OR EQUIVALENT
20nF
4.7μF
16V 30μF
16V
FBN
SWLVS
VIN
VREF
SHDN
SS LT3479
FBP
VC
RTGND
L1
15μH D1
D2
D3
VIN
10V TO 14V
VOUT
–7V TO –10V
1A
VOUT
7V TO 10V
1A
10k
10nF
470pF
470pF
5.76k 26.1k
10.2k 4.99k
3.3nF
4.7μF
16V
F
16V
F
16V
30μF
16V
FBN
SWLVS
VIN
VREF
SHDN
SS LT3479
FBP
SHDN
VC
RTGND
VCTRL
0V-2.5V
L2
15μH
L4
15μH
1A Dual Tracking Power Supply with Adjustable Outputs
IOUT (A)
0
EFFICIENCY (%)
80
75
70
65
60
55
50 0.2 0.4 0.6 0.8
3479 TA11b
1.0
VIN = 14V, VOUT =p7V
VIN =10V, VOUT =p7V
VIN =14V, VOUT =p10V
Effi ciency
LT3479
18
3479fc
PACKAGE DESCRIPTION
3.00 ±0.10
(2 SIDES)
4.00 ±0.10
(2 SIDES)
NOTE:
1. DRAWING PROPOSED TO BE MADE VARIATION OF VERSION (WGED-3) IN JEDEC
PACKAGE OUTLINE MO-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
1.70 ± 0.10
0.75 ±0.05
R = 0.115
TYP
R = 0.05
TYP
3.00 REF
1.70 ± 0.05
17
148
PIN 1
TOP MARK
(SEE NOTE 6)
0.200 REF
0.00 – 0.05
(DE14) DFN 0806 REV B
PIN 1 NOTCH
R = 0.20 OR
0.35 × 45°
CHAMFER
3.00 REF
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
2.20 ±0.05
0.70 ±0.05
3.60 ±0.05
PACKAGE
OUTLINE
0.25 ± 0.05
0.25 ± 0.05
0.50 BSC
3.30 ±0.05
3.30 ±0.10
0.50 BSC
DE Package
14-Lead Plastic DFN (4mm × 3mm)
(Reference LTC DWG # 05-08-1708 Rev B)
LT3479
19
3479fc
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.
PACKAGE DESCRIPTION
FE16 (BC) TSSOP 0204
0.09 – 0.20
(.0035 – .0079)
0o – 8o
0.25
REF
0.50 – 0.75
(.020 – .030)
4.30 – 4.50*
(.169 – .177)
134
5678
10 9
4.90 – 5.10*
(.193 – .201)
16 1514 13 12 11
1.10
(.0433)
MAX
0.05 – 0.15
(.002 – .006)
0.65
(.0256)
BSC
2.94
(.116)
0.195 – 0.30
(.0077 – .0118)
TYP
2
RECOMMENDED SOLDER PAD LAYOUT
0.45 p0.05
0.65 BSC
4.50 p0.10
6.60 p0.10
1.05 p0.10
2.94
(.116)
3.58
(.141)
3.58
(.141)
MILLIMETERS
(INCHES) *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.150mm (.006") PER SIDE
NOTE:
1. CONTROLLING DIMENSION: MILLIMETERS
2. DIMENSIONS ARE IN
3. DRAWING NOT TO SCALE
SEE NOTE 4
4. RECOMMENDED MINIMUM PCB METAL SIZE
FOR EXPOSED PAD ATTACHMENT
6.40
(.252)
BSC
FE Package
16-Lead Plastic TSSOP (4.4mm)
(Reference LTC DWG # 05-08-1663)
Exposed Pad Variation BC
LT3479
20
3479fc
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2004
LT 0809 REV C • PRINTED IN USA
RELATED PARTS
TYPICAL APPLICATION
PART NUMBER DESCRIPTION COMMENTS
LT1618 Constant Current, Constant Voltage 1.4MHz,
High Effi ciency Boost Regulator
VIN: 1.6V to 18V, VOUT(MAX) = 5.5V, IQ = 2.5mA, ISD = <1μA, QFN16 Package
LTC®3216 1A Low Noise High Current LED Charge Pump
with Independent Torch/Flash Current Control
VIN: 2.9V to 4.4V, VOUT(MAX) = 5.5V, IQ = 300μA, ISD = <1μA, DFN12 Package
LTC3436 3A (ISW), 1MHz, 34V Step-Up DC/DC Converter VIN: 3V to 25V, VOUT(MAX) = 34V, IQ = 0.9mA, ISD = <6μA, TSSOP16E Package
LTC3453 Synchronous Buck-Boost High Power White
LED Driver
VIN: 2.7V to 5.5V, VOUT(MAX) = 5.5V, IQ = 2.5mA, ISD = <1μA, QFN16 Package
LT3466 Dual Constant Current, 2MHz, High Effi ciency
White LED Boost Regulator with Integrated
Schottky Diode
VIN: 2.7V to 24V, VOUT(MAX) = 40V, IQ = 5mA, ISD = <16μA, DFN Package
115k
10k
2.49k
0.2Ω ILED
500mA/100mA
7.5k 10k
C1
2.2μF
VIN
3.3V TO 4.2V
D1
D2
D3
M1
L1
4.7μH
3479 TA09
FBN
SWLVS
VIN
VC
GNDRT
VREF
SHDNON
SS
LT3479
FBP
2.2nF
C1, C2: TAIYO YUDEN LMK316BJ225MD
D1: PHILIPS PMEG2010
D2, D3: LUMILEDS LXHL-PW01
L1: SUMIDA CDRH4D28-4R7
M1: VISHAY SILICONIX Si2302ADS
C2
2.2μF
ON
TORCH MODE
ILED = 100mA
FLASH MODE
ILED = 500mA
10nF
Lumiled Driver for Photo Flash with Output Disconnnect
0.2ms/DIV
VOUT
1V/DIV
INDUCTOR
CURRENT
0.5A/DIV
3479 TA09b
Lumileds Start-Up
50μs/DIV
ILED
0.2A/DIV
ILED 500mA m100mA m500mA
VOUT
AC-COUPLED
500mV/DIV
3479 TA09c
Lumileds Torch/Flash Transition