LT3579/LT3579-1
6A Boost/Inverting
DC/DC Converter with Fault Protection
FEATURES
DESCRIPTION
The LT®3579 is a PWM DC/DC converter with built-in fault
protection features to aid in protecting against output shorts,
input/output overvoltage, and overtemperature conditions.
Thepartconsistsofa42Vmasterswitch,anda42Vslaveswitch
that can be tied together for a total current limit of 6A.
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6A, 42V Combined Power Switch
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Output Short Circuit Protection
Wide Input Range: 2.5V to 16V Operating,
40V Maximum Transient
LT3579-1: Dual-Phase Capable
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Master/Slave (3.4A/2.6A) Switch Design
User Configurable Undervoltage Lockout
Easily Configurable as a Boost, SEPIC, Inverting, or
Flyback Converter
The LT3579 is ideal for many local power supply designs. It
canbeeasilyconfiguredinBoost,SEPIC,Inverting,orFlyback
configurations, and is capable of generating 12V at 1.7A, or
–12Vat1.2Afroma5Vinput. Inaddition, theLT3579’sslave
switch allows the part to be configured in high voltage, high
power charge pump topologies that are very efficient and
require fewer components than traditional circuits.
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Low V
Switch: 250mV at 5.5A (Typical)
CESAT
Can be Synchronized to External Clock
Can Synchronize other Switching Regulators
High Gain SHDN Pin Accepts Slowly Varying Input
Signals
TheLT3579’sswitchingfrequencyrangecanbesetbetween
200kHz and 2.5MHz. The part may be clocked internally at
a frequency set by the resistor from the RT pin to ground,
or it may be synchronized to an external clock. A buffered
version of the clock signal is driven out of the CLKOUT
pin, and may be used to synchronize other compatible
switching regulator ICs to the LT3579.
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20-Lead TSSOP and 20-Pin 4mm × 5mm QFN
Packages
APPLICATIONS
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Local Power Supply
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Vacuum Flourescent Display (VFD) Bias Supplies
TheLT3579alsofeaturesinnovativeSHDNpincircuitrythat
allows for slowly varying input signals and an adjustable
undervoltage lockout function. Additional features such
as frequency foldback and soft-start are integrated. The
LT3579 is available in 20-lead TSSOP and 20-pin 4mm ×
5mm QFN packages.
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TFT-LCD Bias Supplies
Automotive Engine Control Unit (ECU) Power
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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.
Protected by U.S. Patents, including 7579816.
TYPICAL APPLICATION
Efficiency and Power Loss
100
90
80
70
60
50
40
30
20
3.2
2.8
2.4
2.0
1.6
1.2
0.8
0.4
0
1MHz, 5V to 12V Boost Converter with Output Short Circuit Protection
2.2μH
V
12V
OUT
V
5V
IN
1.7A
10μF
SW1 SW2
130k 6.3k
10μF
FB
GATE
V
IN
22μF
100k
200k
FAULT
V
IN
LT3579
TEMPERATURE
MONITOR
SHDN
CLKOUT
V
C
RT
8k
2.2nF
SYNC GND SS
86.6k
0.1μF
47pF
0
0.25 0.5 0.75
1
1.25 1.5 1.75
2
3579 TA01
LOAD CURRENT (A)
35791 TA02
35791f
1