LM3243

SW

FB

VCON

PGND SGND

EN

MODE

VBATT

VOUT

ACB

BP

VCC_PA_2G

BB or

RFIC

DAC

GPO2

GPO1

BGND

1.5 µH

10 µF

1.0 µF

PA

4.7 µF

PA(s)

VCC_PA_3G

10 µF

LM3243

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SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013

LM3243 High-Current Step-Down Converter for 2G/3G/4G RF Power Amplifiers

Check for Samples: LM3243

1

FEATURES

DESCRIPTION

The LM3243 is a DC-DC converter optimized for

2

•

High-Efficiency PFM and PWM modes with

powering multi-mode 2G/3G/4G RF power amplifiers

Internal Synchronous Rectification

(PAs) from a single Lithium-Ion cell. The LM3243

•

Analog Bypass Function with Low Dropout

steps down an input voltage from 2.7V to 5.5V to a

Resistance (45 m

Ω typ.)

dynamically adjustable output voltage of 0.4V to 3.6V.

The output voltage is set through a VCON analog

•

Dynamically Adjustable Output Voltage, 0.4V

input that adjusts the output voltage to ensure

to 3.6V (typ.), in PFM and PWM Modes

efficient operation at all power levels of the RF PA.

•

2.5A Maximum Load Current in PWM Mode

The LM3243 operates in constant frequency PWM

•

2.7 MHz (average) PWM Switching Frequency

mode producing a small and predictable amount of

•

Modulated switching frequency to aid Rx Band

output voltage ripple. This enables best ECTEL

Compliance

power requirements in GMSK and EDGE spectral

•

Operates from a Single Li-ion Cell (2.7V to

compliance, with the minimal amount of filtering and

excess headroom. When operating in PFM mode, the

5.5V)

LM3243

enables

the

lowest

DG09

current

•

ACB reduces inductor requirements and size

consumption

and

therefore

maximizes

system

•

Minimum total solution size by using small

efficiency.

footprint and case size inductor and

The LM3243 has a unique Active Current assist and

capacitors

analog Bypass (ACB) feature to minimize inductor

•

16-bump thin DSBGA Package

size without any loss of output regulation for the

•

Current and Thermal Overload Protection

entire battery voltage and RF output power range,

until dropout. ACB provides a parallel current path,

when needed, to limit the maximum inductor current

APPLICATIONS

to 1.4A (typ.) while still driving a 2.5A load. The ACB

•

Cellular Phones

also enables operation with minimal dropout voltage.

•

Hand-Held Radios

The LM3243 is available in a small 2 mm x 2 mm

chip-scale 16-bump DSBGA package.

•

RF PC Cards

•

Battery-Powered RF Devices

If you are considering using the LM3243 in a system

design, please see the PCB Layout Considerations

section of this data sheet.

TYPICAL SYSTEM APPLICATION DIAGRAM

1

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2

All trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.

Copyright © 2010–2013, Texas Instruments Incorporated

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.