LM3243_14 Datasheet, PDF (1/29 Pages) Texas Instruments – High-Current Step-Down Converter for 2G/3G/4G RF Power Amplifiers

LM3243
www.ti.com
SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013
LM3243 High-Current Step-Down Converter for 2G/3G/4G RF Power Amplifiers
Check for Samples: LM3243
FEATURES
1
•2 High-Efficiency PFM and PWM modes with
Internal Synchronous Rectification
• Analog Bypass Function with Low Dropout
Resistance (45 mΩ typ.)
• Dynamically Adjustable Output Voltage, 0.4V
to 3.6V (typ.), in PFM and PWM Modes
• 2.5A Maximum Load Current in PWM Mode
• 2.7 MHz (average) PWM Switching Frequency
• Modulated switching frequency to aid Rx Band
Compliance
• Operates from a Single Li-ion Cell (2.7V to
5.5V)
• ACB reduces inductor requirements and size
• Minimum total solution size by using small
footprint and case size inductor and
capacitors
• 16-bump thin DSBGA Package
• Current and Thermal Overload Protection
APPLICATIONS
• Cellular Phones
• Hand-Held Radios
• RF PC Cards
• Battery-Powered RF Devices
DESCRIPTION
The LM3243 is a DC-DC converter optimized for
powering multi-mode 2G/3G/4G RF power amplifiers
(PAs) from a single Lithium-Ion cell. The LM3243
steps down an input voltage from 2.7V to 5.5V to a
dynamically adjustable output voltage of 0.4V to 3.6V.
The output voltage is set through a VCON analog
input that adjusts the output voltage to ensure
efficient operation at all power levels of the RF PA.
The LM3243 operates in constant frequency PWM
mode producing a small and predictable amount of
output voltage ripple. This enables best ECTEL
power requirements in GMSK and EDGE spectral
compliance, with the minimal amount of filtering and
excess headroom. When operating in PFM mode, the
LM3243 enables the lowest DG09 current
consumption and therefore maximizes system
efficiency.
The LM3243 has a unique Active Current assist and
analog Bypass (ACB) feature to minimize inductor
size without any loss of output regulation for the
entire battery voltage and RF output power range,
until dropout. ACB provides a parallel current path,
when needed, to limit the maximum inductor current
to 1.4A (typ.) while still driving a 2.5A load. The ACB
also enables operation with minimal dropout voltage.
The LM3243 is available in a small 2 mm x 2 mm
chip-scale 16-bump DSBGA package.
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
VBATT
10 µF
GPO1
GPO2
DAC
BB or
RFIC
EN
PV_IN V_DD
SW
BP
LM3243
FB
MODE
ACB
VCON _{PGND SGND BGND}
1.5 µH
VOUT
10 µF
VCC_PA_3G
1.0 µF
VCC_PA_2G
4.7 µF
PA
PA(s)
1
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2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
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