DC-DC Converter. LM3218 Datasheet
Step-Down DC-DC Converter
|Total Page||16 Pages|
January 21, 2009
650 mA Miniature, Adjustable, Step-Down DC-DC
Converter for RF Power Amplifiers
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 VCON 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
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.
■ 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 VIN, 3.4 VOUT at 400 mA)
■ 8-pin LTCC Package
■ Current Overload Protection
■ Thermal Overload Protection
■ Cellular Phones
■ Hand-Held Radios
■ RF PC Cards
■ Battery-Powered RF Devices
FIGURE 1. LM3218 Typical Application
© 2009 National Semiconductor Corporation 300504
NS Package Number SE08A
Package Marking (Note)
250 units, Tape-and-Reel
3000 units, Tape-and-Reel
Note: The actual physical placement of the package marking will vary from part to part. The package marking “X” designates the date code. “V” is a NSC internal
code for die traceability. Both will vary in production. “S” designates device type as switcher and “SA” identifies the device (part number).
Enable Input. Set this digital input high for normal operation. For shutdown, set low.
Voltage Control Analog input. VCON controls VOUT in PWM mode.
Feedback Analog Input. Connect to the VOUT pin.
Analog and Control Ground.
Output Voltage, connects to one terminal of 2.6 µH inductor. Connect output filter capacitor C2 to get DC
Power Supply Voltage Input to the internal Buck PFET switch.
Analog Supply Input.
|Features||Datasheet pdf LM3218 650 mA Miniature, Adjustable, Ste p-Down DC-DC Converter with Integrated Inductor for RF Power Amplifiers Janua ry 21, 2009 LM3218 650 mA Miniature, A djustable, Step-Down DC-DC Converter fo r RF Power Amplifiers General Descripti on The LM3218 is a DC-DC converter with inductor which is optimized for poweri ng RF power amplifiers (PAs) from a sin gle Lithium-Ion cell. It steps down an input voltage in the range from 2.7V to 5.5V to an adjustable output voltage o f 0.8V to 3.6V. Output voltage is set b y using a VCON analog input to control power levels and efficiency of the RF P A. The LM3218 offers superior electrica l performance for mobile phones and sim ilar RF PA applications with a reduced footprint (3mm x 2.5mm x 1.2mm). Fixed- frequency PWM operation minimizes RF in terference. A shutdown function turns t he device off and reduces battery consu mption to 0.01 µA (typ.). The LM3218 i s available in an integrated inductor 8 –pin LTCC package. A high switching frequency (2 MHz typ.) allow.|
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