AAT1171 Datasheet, PDF (1/22 Pages) Advanced Analogic Technologies – 600mA Voltage-Scaling Step-Down Converter for RF Power Amplifiers with Bypass Switch

DATA SHEET
AAT1171
600mA Voltage-Scaling Step-Down Converter
for RF Power Amplifiers with Bypass Switch
General Description
The AAT1171 SwitchReg™ dynamically controls the oper-
ating voltage of a WCDMA or CDMA power amplifier
inside single-cell, lithium-ion battery-powered systems.
The AAT1171 outputs a voltage between 0.6V and 3.6V,
thereby optimizing the amplifier efficiency at both low
and high transmit levels.
The AAT1171 output voltage is controlled via an analog
signal from the baseband processor. It can deliver
600mA of continuous load current while maintaining a
low 45μA of no load quiescent current. The 2MHz switch-
ing frequency minimizes the size of external components
while keeping switching losses low. To further improve
system efficiency, an 85mΩ bypass MOSFET transistor is
also included to allow the PA to be powered directly from
the battery.
The AAT1171 maintains high efficiency thoughout the
entire load range in Light Load (LL) mode, and can be
forced into Pulse Wide Modulation (PWM) mode for low
noise operation or can be synchronized to an external
clock.
The AAT1171 is available in a Pb-free, space-saving
TDFN33-12 or 12-pin wafer-level chip scale package
(WLCSP) and is rated over the -40°C to +85°C tempera-
ture range.
Features
• V_IN Range: 2.7V to 5.5V
• Variable Output Voltage: 0.6V to 3.6V
• 600mA Output Current
• DAC Input: 0.2V to 1.2V
• High Output Accuracy: ±3%
• 45μA No Load Quiescent Current
• Internal Soft Start Limits Startup Current and Output
Voltage Overshoot
• Synchronizable to External 19.8MHz System Clock
• Over-Temperature and Current Limit Protection
• Integrated 85mΩ Bypass MOSFET
• 2MHz Operation
• PWM/LL Control with Override
• Fast Start-Up:
▪ 50μs (AAT1171-4, AAT1171-5)
▪ 150μs (AAT1171-1)
• 100% Duty Cycle Operation
• <30μs Output Voltage Response Time
• 3x3mm 12-Pin TDFN or 1.535x2.235mm 12-Pin
WLCSP Package
• Temperature Range: -40°C to +85°C
Applications
• WCDMA or CDMA PA in Cellular Phones, Smartphones,
Feature Phones, etc.
• Express Card
• PCMCIA Data Cards
Typical Application
C_IN
–
4.7μF
VIN
VCC
LX
AAT1171-1/
AAT1171-4
BYPASS
VOUT
MODE/SYNC
EN
DAC GNDx2
L1
2.2μH
0.6V - 3.6V
C_OUT
4.7μF
VCC2 V_CONT
VREF
VCC2
PA
DAC
TX
Baseband
Processor
RX
VIN
VCC
L1
4.7μH
LX
0.6V - 3.6V
C_IN
–
4.7μF
AAT1171-5
BYPASS
VOUT
MODE/SYNC
EN
DAC GNDx2
C_OUT
10μF
VCC2 V_CONT
VREF
VCC2
PA
DAC
TX
Baseband
Processor
RX
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
201999B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013
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