Miniature, Adjustable, Step-Down DC-DC Converter with Bypass Mode for RF Power Amplifiers

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 VCON 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 DSBGA package. A high switching frequency (2MHz) allows use of tiny surface-mount components.