A Speaker Protection Scheme for Class D PWM Amplifiers

Alexandre Huffenus(1), Gael Pillonnet(2), Robert Cittadini(3), Vincent Rabary(3).
(1) EASII IC, Grenoble, France. (2) Institut des Nanotechnologies de Lyon, Villeurbanne, France. (3) ST Microelectronics, Grenoble, France.

Switched mode (class D) audio amplifiers gained much popularity in low power applications during the last decade thanks to their high efficiency, compactness, and increasing sound quality. They have become the technology of choice for battery operated systems such as mobile phones, PDAs, portable media players, etc. In such applications it is critical to protect the microspeakers from an excessive output power that could result from severe amplifier clipping. A current and area effective solution is presented in this paper, to limit the clipping from the Class D amplifier.

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