LM3208 Datasheet, PDF (1/17 Pages) National Semiconductor (TI) – 650mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power Amplifiers

April 2006
LM3208
650mA Miniature, Adjustable, Step-Down DC-DC
Converter for RF Power Amplifiers
General Description
The LM3208 is a DC-DC converter optimized for powering
RF power amplifiers (PAs) from a single Lithium-Ion cell.
However, it may be used in many other applications. 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 LM3208 offers superior performance for mobile phones
and similar RF PA applications. Fixed-frequency PWM op-
eration minimizes RF interference. A shutdown function turns
the device off and reduces battery consumption to 0.01 µA
(typ.).
The LM3208 is available in an 8-pin lead-free micro SMD
package. A high switching frequency (2 MHz typ.) 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 Adjustable Output Voltage (0.8V to 3.6V)
n Fast Output Voltage Transient (0.8V to 3.4V in 25µs
typ.)
n 650mA Maximum load capability
n High Efficiency (95% typ. at 3.9V_IN, 3.4V_OUT at 400mA)
n 8-pin micro SMD Package
n Current Overload Protection
n Thermal Overload Protection
Applications
n Cellular Phones
n Hand-Held Radios
n RF PC Cards
n Battery Powered RF Devices
Typical Application
FIGURE 1. LM3208 Typical Application
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© 2006 National Semiconductor Corporation DS201663
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