LM3218 Datasheet, PDF (1/16 Pages) National Semiconductor (TI) – 650 mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power Amplifiers

January 21, 2009
LM3218
650 mA Miniature, Adjustable, Step-Down DC-DC
Converter for RF Power Amplifiers
General Description
The LM3218 is a DC-DC converter with inductor which is op-
timized 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 foot-
print (3mm x 2.5mm x 1.2mm). Fixed-frequency PWM oper-
ation 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 LTCC
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 re-
quired. The overall board space is reduced up to 25% from
the typical discrete inductor solution.
Features
■ ^{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 LTCC Package}
■ ^{Current Overload Protection}
■ ^{Thermal Overload Protection}
Applications
■ ^{Cellular Phones}
■ ^{Hand-Held Radios}
■ ^{RF PC Cards}
■ ^{Battery-Powered RF Devices}
Typical Application
FIGURE 1. LM3218 Typical Application
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