Texas Instruments Incorporated
Analog based speaker thermal protection in class-D amplifiers

Abstract:

A circuit comprises a sensing resistor with a resistance Rs, a first amplifier circuit with a first gain factor G, a second amplifier circuit with a second gain factor (1/A), a third amplifier circuit, a current mirror, a buffer, and a peak voltage detector. The first amplifier circuit is coupled to the sensing resistor at a first node and a second node and to the second amplifier circuit, which is further coupled to the current mirror. The buffer is coupled to the current mirror and to the third amplifier circuit, which is further coupled to the peak voltage detector and configured to receive a voltage across a load and a voltage on a ground node. In some implementations, the load is a speaker. In some implementations, a filter is coupled between the first and the second amplifier circuits.