High Efficiency, Low Noise, Fast Transient
400mA Step-Down Converter
General Description
The AAT1147 SwitchReg is a member of
AnalogicTech's Total Power Management IC™
(TPMIC™) product family. It is a fixed frequency
1.4MHz step-down converter with an input volt-
age range of 2.7V to 5.5V and output voltage as
low as 0.6V.
The AAT1147 is optimized for low noise portable
applications, reacts quickly to load variations, and
reaches peak efficiency at heavy load.
The AAT1147 output voltage is programmable with
external feedback resistors. It can deliver 400mA
of load current while maintaining high power effi-
ciency. The 1.4MHz switching frequency mini-
mizes the size of external components while keep-
ing switching losses low.
The AAT1147 is available in a Pb-free, space-sav-
ing 2.0x2.1mm SC70JW-8 package and is rated
over the -40°C to +85°C temperature range.
AAT1147
Features
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SwitchReg
™
V
IN
Range: 2.7V to 5.5V
V
OUT
Adjustable from 0.6V to V
IN
400mA Output Current
Up to 98% Efficiency
Low Noise, 1.4MHz Fixed Frequency PWM
Operation
Fast Load Transient
150µs Soft Start
Over-Temperature and Current Limit
Protection
100% Duty Cycle Low Dropout Operation
<1µA Shutdown Current
8-Pin SC70JW 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
1
U1
AAT1147
VIN
EN
AGND
PGND
LX
OUT
PGND
PGND
4
2
7
6
V
O
= 1.8V
L1
4.7μH
R1
118k
R2
59k
C1
4.7μF
C2
4.7μF
5
8
1147.2006.05.1.0
1
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
