800mA Voltage-Scaling Step-Down Converter
General Description
The AAT1142 SwitchReg is a dynamically pro-
grammable 2.2MHz step-down converter with an
input voltage range of 2.7V to 5.5V and output from
0.6V to 2.0V. Its low supply current, high level of
integration, and small footprint make the AAT1142
the ideal choice for microprocessor core power in
systems such as smartphones.
The 2.2MHz switching frequency allows the use of
a small external inductor and capacitors. Peak cur-
rent mode control and internal compensation pro-
vide stable operation and fast voltage response
without over/undershoot or ringing.
The AAT1142 delivers up to 800mA of output current
while consuming 35µA of typical no load quiescent
current. Dynamic Voltage Management is provided
through I
2
C or AnalogicTech's S
2
Cwire™ (Simple
Serial Control™) single wire interface. The user can
program the output from 0.6V to 2.0V in 50mV steps.
The AAT1142 optimizes power efficiency through-
out the load range via PWM/PFM mode. Pulling
the MODE/SYNC pin high enables PWM Only
mode, maintaining constant frequency and low
noise across the operating range. Alternatively, the
converter may be synchronized to an external
clock input via the MODE/SYNC pin. Over-temper-
ature and short-circuit protection safeguard the
AAT1142 and system components from damage.
The AAT1142 is available in a Pb-free, space-sav-
ing 2.85x3.0x1.0mm TSOPJW-12 package or a
Pb-free, low-profile 3x3x0.8mm TDFN33-12 pack-
age. The device is rated over the -40°C to +85°C
temperature range.
AAT1142
Features
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•
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•
•
•
•
•
•
•
•
•
•
•
•
SwitchReg
™
•
•
V
IN
Range: 2.7V to 5.5V
V
OUT
Programmable Range: 0.6V to 2.0V
Dynamic Voltage Management:
— 50mV Output Resolution
— Fast, Stable Response
Serial Control Options:
— I
2
C Two-Wire Interface
— S
2
Cwire Single-Wire Interface
800mA Output Current
Up to 93% Efficiency
Line, Load Regulation Less Than ±0.5%
2.2MHz Switching Frequency
Ultra-Small External Filter
Low 35µA No Load Quiescent Current
100% Duty Cycle Low Dropout Operation
Internal Soft Start
Over-Temperature Protection
Current Limit Protection
Multi-Function MODE/SYNC Pin:
— PFM/PWM for High Efficiency
— PWM Only for Low Noise
— Clock Input to Synchronize to System Clock
TSOPJW-12 or TDFN33-12 Package
Temperature Range: -40°C to +85°C
Applications
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Camcorders
Cellular Phones and Smartphones
Digital Still Cameras
Handheld Instruments
Microprocessor / DSP Core
MP3, Portable Music, and Portable Media
Players
PDAs and Handheld Computers
Efficiency vs. Load
Typical Application
V
IN
: 2.7V to 5.5V
L
1
VIN
C
2
4.7µF
LX
2.2µH
V
OUT
: 0.6V to 2.0V
800mA Maximum
(V
OUT
= 1.8V)
100
90
V
IN
= 3.6V V
IN
= 2.7V
Efficiency (%)
AAT1142
FB
MODE/SYNC
SDA
SCL
EN/SET
AGND
PGND
C
1
10µF
80
70
60
50
40
30
0
1
10
100
1000
V
IN
= 4.2V
V
IN
= 5.0V
PWM Only
Mode
I
2
C
S Cwire*
2
*Optional S
2
Cwire or I
2
C Input
Output Current (mA)
1142.2006.07.1.0
1
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
