LM3203 Datasheet, PDF (1/15 Pages) National Semiconductor (TI) – Step-Down DC-DC Converter with Bypass Mode for CDMA / WCDMA RF Power Amplifiers

July 2005
LM3203
Step-Down DC-DC Converter with Bypass Mode for
CDMA / WCDMA RF Power Amplifiers
General Description
The LM3203 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 of 2.7V to 5.5V to an adjustable
output voltage of 0.8V to 3.6V. The output voltage is set
using a V_CON analog input and external resistor dividers for
optimizing efficiency of the RF PA at various power levels.
The LM3203 offers 3 modes for mobile phones and similar
RF PA applications. Fixed-frequency PWM mode minimizes
RF interference. Bypass mode turns on an internal bypass
switch to power the PA directly from the battery. Shutdown
mode turns the device off and reduces battery consumption
to 0.1µA (typ.).
The LM3203 is available in a 10-pin lead free micro SMD
package. A high switching frequency (2MHz) allows use of
tiny surface-mount components.
Features
n 2MHz (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 500mA Maximum load capability (PWM and Bypass
mode)
n PWM / Forced Bypass Mode
n Low R_DSON Bypass FET: 85mΩ (typ.)
n High Efficiency (96% typ. at 3.6V_IN, 3.2V_OUT at 150mA)
n Fast Turn-on time when Enabled (50µs typ.), 3GPP
Compliant
n 10-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
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