AN1042 - ON Semiconductor

AN1042 High Fidelity Switching Audio Amplifiers Using TMOS Power MOSFETs

AN1042/D High Fidelity Switching Audio Amplifiers Using TMOS Power MOSFETs Prepared by: Donald E. Pauly ON Semiconductor Special Consultant http://onsemi.com APPLICATION NOTE With the introduction of complementary bipolar power transistors in the late 1960s, switching amplifiers became theoretically practical. At low frequencies, bipolar transistors have sw.

Features

es at a carrier frequency of 120 kHz. Its duty cycle can vary from 5% to 95% which allows the speaker voltage to reach 90% of either the positive or negative supplies. The filter has a response in the audio frequency range that is as flat as possible, with high attenuation of the carrier frequency and its harmonics. A 0.05 ohm current sense resistor (R27) is used in the ground return of the filter and speaker to provide short circuit protection. The negative feedback loop is closed before the filter to prevent instabilities. Feedback cannot be taken from the speaker because of the phase shift .