LTC3427_15 Datasheet, PDF (1/12 Pages) Linear Technology – 500mA, 1.25MHz Synchronous Step-Up DC/DC Converter in 2mm 2mm DFN Package

FEATURES
■ _{High Efficiency: Up to 94%}
■ _{3.3V at 200mA from Two Alkaline Cells}
■ _{5V at 200mA from a Single Li-Ion Cell}
■ _{Inrush Current Limiting and Soft-Start}
■ _{Output Disconnect in Shutdown}
■ _{1.8V to 5V VIN Range}
■ _{1.8V to 5.25V VOUT Range}
■ _{1.25MHz Fixed Frequency, Low Noise PWM}
■ _{Internal Synchronous Rectifier}
■ _{Logic Controlled Shutdown (<1µA)}
■ _{Anti-Ringing Control Minimizes EMI}
■ _{Tiny External Components}
■ _{Short-Circuit Protection}
■ _{Low Profile (0.75mm × 2mm × 2mm) DFN Package}
U
APPLICATIO S
■ _{Handheld Instruments}
■ _{Digital Cameras}
■ _{Wireless Handsets}
■ _{GPS Receivers}
■ _{Portable Medical Devices}
■ _{MP3 Players}
LTC3427
500mA, 1.25MHz
Synchronous Step-Up
DC/DC Converter in
2mm × 2mm DFN Package
DESCRIPTIO
The LTC^®3427 is the industry’s first high efficiency, fixed
frequency, step-up DC/DC converter with true output
disconnect in a 6-lead 2mm × 2mm DFN package. Requir-
ing minimal external components, the LTC3427 operates
from an input voltage as low as 1.8V. The LTC3427
contains an internal 0.525Ω N-channel MOSFET switch
and a 0.575Ω P-channel MOSFET synchronous rectifier,
which enables it to supply 200mA at 3.3V from a 2-cell
alkaline battery input.
The LTC3427 limits inrush current during start-up and
provides a soft-start of V_OUT. A switching frequency of
1.25MHz minimizes solution footprint by allowing the use
of tiny, low profile inductors and ceramic capacitors and
produces very low V_OUT ripple. The current mode PWM
design is internally compensated, reducing external parts
count. Anti-ringing control reduces EMI in discontinuous
mode operation. The LTC3427 also features low shut-
down current of under 1µA and thermal shutdown.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATIO
2-Cell Alkaline to 3.3V Synchronous Boost Converter
V_IN
1.8V TO 3.2V _{2-CELL +}
ALKALINE
2.2µF
OFF ON
4.7µH
V_IN
SW
LTC3427
SHDN V_OUT
GND
FB
1000k
604k
V_OUT
3.3V
200mA
4.7µF
3427 TA01a
100
95
90
85
80
75
70
10
2.4V to 3.3V Efficiency
1000
EFFICIENCY
100
POWER LOSS
100
LOAD CURRENT (mA)
10
1000
3427 TA01b
3427fa
1