LT3580
Boost/Inverting DC/DC
Converter with 2A Switch,
Soft-Start, and Synchronization
FEATURES
DESCRIPTION
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The LT®3580 is a PWM DC/DC converter containing an
internal 2A, 42V switch. The LT3580 can be configured
as either a boost, SEPIC or inverting converter. Capable
of generating 12V at 550mA or –12V at 350mA from a
5V input, the LT3580 is ideal for many local power supply
designs.
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2A Internal Power Switch
Adjustable Switching Frequency
Single Feedback Resistor Sets VOUT
Synchronizable to External Clock
High Gain SHDN Pin Accepts Slowly Varying
Input Signals
Wide Input Voltage Range: 2.5V to 32V
Low VCESAT Switch: 300mV at 1.5A (Typical)
Integrated Soft-Start Function
Easily Configurable as a Boost or Inverting Converter
User Configurable Undervoltage Lockout (UVLO)
Tiny 8-Lead 3mm × 3mm DFN and 8-Lead MSOP
Packages
APPLICATIONS
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The LT3580 has an adjustable oscillator, set by a resistor
from the RT pin to ground. Additionally, the LT3580 can
be synchronized to an external clock. The free running or
synchronized switching frequency range of the part can
be set between 200kHz and 2.5MHz.
The LT3580 also features innovative SHDN pin circuitry
that allows for slowly varying input signals and an adjustable undervoltage lockout function.
Additional features such as frequency foldback and
soft-start are integrated. The LT3580 is available in tiny
3mm × 3mm 8-lead DFN and 8-lead MSOP packages.
VFD Bias Supplies
TFT-LCD Bias Supplies
GPS Receivers
DSL Modems
Local Power Supply
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.
TYPICAL APPLICATION
1.2MHz, 5V to 12V Boost Converter Achieves Over 88% Efficiency
Efficiency and Power Loss
95
4.2μH
SHDN
GND
130k
LT3580
RT
FB
VC
SYNC
2.2μF
75k
1000
85
10μF
SW
SS
10k
0.1μF
1nF
80
800
75
600
70
65
400
POWER LOSS (mW)
VIN
1200
90
EFFICIENCY (%)
VIN
5V
VOUT
12V
550mA
60
200
3580 TA01
55
50
0
0
100
200
300
400
LOAD CURRENT (mA)
500
600
3580 TA01b
3580fg
1
