LM3218 Datasheet, PDF (1/21 Pages) National Semiconductor (TI) – 650 mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power Amplifiers

LM3218
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SNOSB11B – MARCH 2008 – REVISED MARCH 2013
LM3218 650 mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power
Amplifiers
Check for Samples: LM3218
FEATURES
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•2 Includes 2.6 µH Inductor in Very Small Form
Factor (3mm x 2.5mm x 1.2mm)
• 2 MHz (typ.) PWM Switching Frequency
• Operates from a Single Li-Ion Cell (2.7V to
5.5V)
• Adjustable Output Voltage (0.8V to 3.6V)
• Fast Output Voltage Transient (0.8V to 3.4V in
25 µs typ.)
• 650 mA Maximum Load Capability
• High Efficiency (95% typ. at 3.9 V_IN, 3.4 V_OUT at
400 mA)
• 8-pin POS Package
• Current Overload Protection
• Thermal Overload Protection
APPLICATIONS
• Cellular Phones
• Hand-Held Radios
• RF PC Cards
• Battery-Powered RF Devices
DESCRIPTION
The LM3218 is a DC-DC converter with inductor
which is optimized for powering RF power amplifiers
(PAs) from a single Lithium-Ion cell. It steps down an
input voltage in the range from 2.7V to 5.5V to an
adjustable output voltage of 0.8V to 3.6V. Output
voltage is set by using a V_CON analog input to control
power levels and efficiency of the RF PA.
The LM3218 offers superior electrical performance for
mobile phones and similar RF PA applications with a
reduced footprint (3mm x 2.5mm x 1.2mm). Fixed-
frequency PWM operation minimizes RF interference.
A shutdown function turns the device off and reduces
battery consumption to 0.01 µA (typ.).
The LM3218 is available in an integrated inductor
8–pin POS package. A high switching frequency (2
MHz typ.) allows use of tiny surface-mount
components. Only two small external surface-mount
components, two ceramic capacitors, are required.
The overall board space is reduced up to 25% from
the typical discrete inductor solution.
TYPICAL APPLICATION
V_IN
C_IN
GND
V_IN
V_DD
EN
V_OUT = 2.5 x V_CON
0.8V to 3.6V
V_OUT
LM3218
FB
V_CON
GND
SGND
C_OUT
Integrated Inductor
LM3218
Figure 1. LM3218 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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