LTC3539 Datasheet, PDF (1/12 Pages) Linear Technology – 2A, 1MHz/2MHz Synchronous Step-Up DC/DC Converters

LTC3539/LTC3539-2
2A, 1MHz/2MHz
Synchronous Step-Up
DC/DC Converters
FEATURES
n _{Delivers 3.3V at 900mA From 2 Alkaline/NiMH Cells}
n _{Delivers 5V at 900mA From a Lithium-Polymer}
Battery
n _{VIN Start-Up Voltage: 700mV}
n _{1.5V to 5.25V VOUT Range}
n _{Up to 94% Efficiency}
n _{VIN > VOUT Operation}
n _{1MHz (LTC3539) or 2MHz (LTC3539-2) Fixed}
Frequency Operation
n _{Output Disconnect}
n _{Selectable Burst Mode}^® _{or PWM Operation}
n _{10μA Quiescent Current}
n _{Logic Controlled Shutdown: <1μA}
n _{Requires Only 6 External Components}
n _{Low Profile (2mm × 3mm × 0.75mm) DFN Package}
APPLICATIONS
n _{Medical Instruments}
n _{Portable Bar Code Scanners}
n _{Noise Canceling Headphones}
n _{Portable GPS Navigation}
n _{Handheld PCs}
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.
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.
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.
TYPICAL APPLICATION
Wide V_IN, High Power 3.3V Regulator
V_IN
1.8V TO 3.6V
2.2μF
4.7μH
V_IN
SW
LTC3539
PWM BURST
MODE
V_OUT
1M
OFF ON SHDN
FB
22pF
GND PGND
562k
V_OUT
3.3V
600mA
22μF
3539 TA01a
Efficiency and Power Loss vs
Load Current
100
1000
90
80
EFFICIENCY
100
70
60
50
V_IN = 2.4V
V_OUT = 3.3V
40
30
20
10
POWER LOSS
1
10
0
0.1
FREQUENCY = 1MHz
FREQUENCY = 2MHz
0.1
1
10
100
1000
I_LOAD AVERAGE (mA)
3539 TA01b
3539f
1