PRODUCT DATASHEET
AAT1
149B
SwitchReg
TM
General Description
The AAT1149B SwitchReg is a 2.2MHz step-down con-
verter with an input voltage range of 2.2V to 5.5V. It is
optimized to react quickly to load variations and operate
with a tiny 0603 inductor that is only 1mm tall.
The AAT1149B can deliver 400mA of load current while
maintaining a low 45μA no load quiescent current. The
2.2MHz switching frequency minimizes the size of exter-
nal components while keeping switching losses low.
The AAT1149B maintains high efficiency throughout the
operating range, which is critical for portable applica-
tions.
The AAT1149B is available in a Pb-free, space-saving
5-pin wafer-level chip scale (WLCSP) package and is
rated over the -40°C to +85°C temperature range.
2.2MHz Fast Transient 400mA Step-Down Converter
Features
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Ultra-Small 0603 Inductor (Height = 1mm)
V
IN
Range: 2.2V to 5.5V
V
OUT
Fixed 1.8V
400mA Max Output Current
Up to 98% Efficiency
45μA No Load Quiescent Current
2.2MHz Switching Frequency
70μs Soft Start
Fast Load Transient
Over-Temperature Protection
Current Limit Protection
100% Duty Cycle Low-Dropout Operation
<1μA Shutdown Current
0.9x1.2mm WLCSP Package
Temperature Range: -40°C to +85°C
Applications
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Cellular Phones
Digital Cameras
Handheld Instruments
Microprocessor / DSP Core / IO Power
PDAs and Handheld Computers
USB Devices
Typical Application
V
IN
= 3.6V
U1
AAT1149B
V
OUT
= 1.8V
L1 2.2µH
IN
C2
4.7µF
EN
AGND
PGND
LX
FB
PGND
PGND
C1
4.7µF
1149B.2008.07.1.0
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