LM3205 Datasheet, PDF (1/24 Pages) National Semiconductor (TI) – 650mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power Amplifiers

LM3205
www.ti.com
SNVS388D – JULY 2005 – REVISED MAY 2009
LM3205 650mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power
Amplifiers
Check for Samples: LM3205
FEATURES
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•2 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
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 operation 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.
TYPICAL APPLICATION
V_IN
2.7V to 5.5V
10 PF
PV_IN
EN
V_DD
SW
LM3205
FB
V_{CON PGND SGND}
3.3 PH
V_OUT
0.8V to 3.6V
V_OUT = 2.5 x V_CON
4.7 PF
Figure 1. LM3205 Typical Application
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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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