LM3205 Datasheet, PDF (1/18 Pages) National Semiconductor (TI) – 650mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power Amplifiers

January 2006
LM3205
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 op-
eration 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 required.
Features
n 2 MHz (typ.) PWM Switching Frequency
n Operates from a single Li-Ion cell (2.7V to 5.5V)
n Variable Output Voltage (0.8V to 3.6V)
n Fast Output Voltage Transient (0.8V to 3.6V in 20µs)
n 650mA Maximum load capability
n High Efficiency (96% Typ at 4.2V_IN, 3.4V_OUT at 400mA)
from internal synchronous rectification
n Current Overload Protection
n Thermal Overload Protection
Packages
n 8-Pin microSMD (Lead Free)
n 10-Pin LLP
Applications
n Cellular Phones
n Hand-Held Radios
n RF PC Cards
n Battery Powered RF Devices
Typical Application
FIGURE 1. LM3205 Typical Application
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© 2006 National Semiconductor Corporation DS201580
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