Abstract: An amplifier output stage having an output transistor connected to a high supply voltage and a bootstrap terminal coupled to a control terminal of the output transistor through control circuitry. The output stage includes a capacitor arranged between the bootstrap terminal and the output terminal of the output stage for elevating the voltage at the bootstrap terminal above the high supply voltage, and circuitry for limiting the voltage at the bootstrap terminal to a predetermined threshold. The circuitry for limiting the voltage at the bootstrap terminal directly acts on the control terminal of the output transistor to reduce the conductivity of the output transistor when the voltage at the bootstrap terminal exceeds the predetermined threshold.

Abstract: The present invention relates to a current sense device for a load arranged in a diagonal of a H-bridge comprising MOS transistors (M1, M2, M3, M4) and operating in class AB, characterized in that it includes sensor, independent from the H-bridge, for measuring the current flowing in the load. A current-voltage converter converts the current measured by said sensor into a voltage proportional to said current. The voltage is applied to a sense amplifier that determines the transconductance gain of a control amplifier of the transistors of the H-bridge.