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Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

201999B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013

AAT1171

600mA Voltage-Scaling Step-Down Converter

for RF Power Amplifiers with Bypass Switch

DATA SHEET

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

• 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:

• 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

AAT1171-1/

AAT1171-4

PA

Baseband

Processor

TX

RX

DAC

0.6V - 3.6V

LX

VOUT

GNDx2

DAC

VIN

4.7μF

4.7μF

2.2μH

EN

MODE/SYNC

BYPASS

VCC

–

C

IN

C

OUT

L1

AAT1171-5

PA

Baseband

Processor

TX

RX

DAC

0.6V - 3.6V

LX

VOUT

GNDx2

DAC

VIN

4.7μF

10μF

4.7μH

EN

MODE/SYNC

BYPASS

VCC

–

C

IN

C

OUT

L1