This reference design provides a variable output power for audio amplifiers from 5 V to 35 V controllable by a Pulse Width Modulator signal. The output power capability of 75 W RMS and 300 W peak is suitable for high power automotive audio amplifiers. Conversion is 4-switch Buck-Boost for greater than 95% conversion efficiency. Output can be slewed over the 5 V to 35 V range with ~1 millisecond response time to maximize efficiency of the audio amplifier using this power. This design includes schematic: Bill of Materials: layout files and a test report.