LM3205_09 Datasheet, PDF (1/18 Pages) National Semiconductor (TI) – 650mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power Amplifiers

LM3205
May 27, 2009
650mA Miniature, Adjustable, Step-Down DC-DC Converter
for RF Power Amplifiers
General Description
The LM3205 is a DC-DC converter optimized for powering RF
power amplifiers (PAs) from a single Lithium-Ion cell, however
they may be used in many other applications. It steps down
an input voltage from 2.7V to 5.5V to a variable output voltage
from 0.8V(typ.) to 3.6V(typ.). Output voltage is set using a
V_CON analog input for controlling power levels and efficiency
of the RF PA.
The LM3205 offers superior performance for mobile phones
and similar RF PA applications. Fixed-frequency PWM oper-
ation minimizes RF interference. Shutdown function turns the
device off and reduces battery consumption to 0.01 µA (typ.).
The LM3205 is available in micro SMD package and LLP
package. For all other package options contact your local
NSC sales office.
A high switching frequency (2 MHz) allows use of tiny surface-
mount components. Only three small external surface-mount
components, an inductor and two ceramic capacitors are re-
quired.
Features
■ ^{2 MHz (typ.) PWM Switching Frequency}
■ ^{Operates from a single Li-Ion cell (2.7V to 5.5V)}
■ ^{Variable Output Voltage (0.8V to 3.6V)}
■ ^{Fast Output Voltage Transient (0.8V to 3.6V in 20µs)}
■ ^{650mA Maximum load capability}
■ ^{High Efficiency (96% Typ at 4.2V}_IN^{, 3.4V}_OUT ^{at 400mA)}
from internal synchronous rectification
■ ^{Current Overload Protection}
■ ^{Thermal Overload Protection}
Packages
■ ^{8-Pin microSMD (Lead Free)}
■ ^{10-Pin LLP}
Applications
■ ^{Cellular Phones}
■ ^{Hand-Held Radios}
■ ^{RF PC Cards}
■ ^{Battery Powered RF Devices}
Typical Application
FIGURE 1. LM3205 Typical Application
20158001
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