LTC3539/LTC3539-2
2A, 1MHz/2MHz
Synchronous Step-Up
DC/DC Converters
FEATURES
DESCRIPTION
The LTC®3539/LTC3539-2 are synchronous, 2A step-up
DC/DC converters with output disconnect. Synchronous
rectification enables high efficiency in the low profile
2mm × 3mm DFN package. Battery life is extended with
a 700mV start-up voltage and operation down to 500mV
once started.
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Delivers 3.3V at 900mA From 2 Alkaline/NiMH Cells
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Delivers 5V at 900mA From a Lithium-Polymer
Battery
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V Start-Up Voltage: 700mV
IN
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1.5V to 5.25V V
Range
OUT
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Up to 94% Efficiency
V > V Operation
IN
OUT
A switching frequency of 1MHz (LTC3539) or 2MHz
(LTC3539-2) minimizes solution footprint by allowing the
use of tiny, low profile inductors and ceramic capacitors.
The current mode PWM design is internally compensated,
reducing external parts count. The LTC3539/LTC3539-2
feature a pin-enabled automatic Burst Mode operation at
light load conditions. Anti-ring circuitry reduces EMI by
damping the inductor in discontinuous mode. Additional
features include a low shutdown current of under 1μA and
thermal overload protection.
1MHz (LTC3539) or 2MHz (LTC3539-2) Fixed
Frequency Operation
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Output Disconnect
Selectable Burst Mode® or PWM Operation
10μA Quiescent Current
Logic Controlled Shutdown: <1μA
Requires Only 6 External Components
Low Profile (2mm × 3mm × 0.75mm) DFN Package
APPLICATIONS
The LTC3539/LTC3539-2 are offered in a 2mm × 3mm ×
0.75mm DFN package.
L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
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Medical Instruments
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Portable Bar Code Scanners
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Noise Canceling Headphones
Portable GPS Navigation
Handheld PCs
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TYPICAL APPLICATION
Wide VIN, High Power 3.3V Regulator
Efficiency and Power Loss vs
Load Current
4.7μH
100
90
80
70
60
50
40
30
20
10
0
1000
100
10
V
IN
1.8V TO 3.6V
2.2μF
EFFICIENCY
V
SW
IN
LTC3539
V
OUT
PWM BURST
OFF ON
MODE
V
OUT
3.3V
V
V
= 2.4V
IN
OUT
600mA
1M
22pF
= 3.3V
POWER LOSS
SHDN
FB
22μF
GND PGND
562k
1
3539 TA01a
FREQUENCY = 1MHz
FREQUENCY = 2MHz
0.1
1000
0.1
1
10
100
I
AVERAGE (mA)
LOAD
3539 TA01b
3539f
1