LM3253 Datasheet, PDF (1/5 Pages) Texas Instruments – High-Current Step-Down Converter for 2G/3G/4G RF Power

LM3253
PRODUCT BRIEF
March 16, 2012
High-Current Step-Down Converter for 2G/3G/4G RF Power
Amplifiers
General Description
The LM3253 is a DC-DC converter optimized for powering
multi-mode 2G/3G/4G RF power amplifiers (PAs) from a sin-
gle Lithium-Ion cell. The LM3253 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 LM3253 is
optimized for USB datacard applications.
The LM3253 operates in constant frequency PWM mode pro-
ducing a small and predictable amount of output voltage
ripple. This enables best ECTEL power requirements in GM-
SK and EDGE spectral compliance, with the minimal amount
of filtering and excess headroom. When operating in PFM
mode, the LM3253 enables the lowest DG09 current con-
sumption and therefore maximizes system efficiency.
The LM3253 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 1.84A (typ.) while still driving a 3.0A load. The ACB
also enables operation with minimal dropout voltage. The
LM3253 is available in a small 2 mm x 2 mm chip-scale 16-
bump micro SMD package.
Notice: This document is not a datasheet. For more in-
formation regarding this product or to order samples,
please contact your local Texas Instruments sales office.
Features
■ ^{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
■ ^{3.0A 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 micro SMD Package}
■ ^{Current and Thermal Overload Protection}
Applications
■ ^{USB Datacards}
■ ^{Cellular Phones}
■ ^{Hand-Held Radios}
■ ^{RF PC Cards}
■ ^{Battery-Powered RF Devices}
Typical System Application Diagram
© 2012 Texas Instruments Incorporated 301797 SNVS791A
30179701
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