"According to a preferred embodiment of the present invention, the temperature detector comprises a thermal couple and an amplifier. The thermal couple comprises a first metal line and a second metal line, wherein the first terminal of the first metal line is coupled to the first terminal of the second metal line. The first terminal of the first metal line is coupled to the output stage amplifier. The amplifier is coupled to the second terminals of the first metal line and the second metal line to output the temperature signal.
"An integrated audio amplifier is also provided in the present invention. The audio amplifier comprises a pre-amplifier, an output stage amplifier, a temperature detector and a gain adjusting circuit. The pre-amplifier receives an audio signal for amplifying the audio signal to generate an amplified audio signal. The output stage amplifier is used for receiving the amplified audio signal to output to the load. The temperature detector is used for detecting the temperature of the output stage amplifier to output a temperature signal. The gain adjusting circuit is used for adjusting the amplitude of the amplified audio signal according to the temperature signal, wherein the pre-amplifier, the output stage amplifier, the temperature detector and the gain adjusting circuit is integrated into a same integrated circuit.
"According to a preferred embodiment of the present invention, the temperature detector comprises a diode, a reference voltage generator and an amplifier. The diode comprises an anode terminal and a cathode terminal. The anode terminal thereof is coupled to a bias. The cathode terminal thereof is coupled to a common voltage. The diode is disposed nearby the heat source of the integrated audio amplifier. The reference voltage generator is used for generating a reference voltage. The amplifier comprises a first input terminal, a second input terminal and an output terminal. The first input terminal thereof is coupled to the anode terminal of the diode. The second input terminal thereof is coupled to the reference voltage generator for receiving the reference voltage. The output terminal thereof is used for outputting the temperature. In a further embodiment, the reference voltage generator comprises a band-gap reference circuit.
"A method for protecting an audio amplifier is further provided in the present invention. The method comprises the steps of: (a) detecting a temperature of a heat source of the audio amplifier; (b) determining whether the temperature is greater than a temperature threshold; © returning to step (b) when the temperature is smaller than the temperature threshold; and (d) adaptively adjusting an amplitude of an output signal of the audio amplifier according to value of the temperature when the temperature is greater than the temperature threshold, wherein the higher the value of the temperature is, the smaller the amplitude of the output signal of the audio amplifier is adjusted.
"The spirit of the present invention is to integrate the gain adjusting mechanism and the temperature protect. When the temperature is greater than a preset threshold, the gain would be reduced with the increment of the temperature, such that the audio interrupt is avoided and the uncomfortable feeling on user's hearing can be reduced.
"Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description."
For the URL and additional information on this patent, see: Lee, Kung-Wang; Liao, Tung-Tsai. Circuit for Thermal Protection in Audio Power Amplifier and Method. U.S. Patent Number 8508300, filed
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