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Apparatus and method of limiting power applied to a loudspeaker

  • US 6,940,981 B2
  • Filed: 09/16/2003
  • Issued: 09/06/2005
  • Est. Priority Date: 03/12/2003
  • Status: Active Grant
First Claim
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1. An apparatus to limit power to a load, comprising:

  • a power source to drive the load using an input signal;

    a voltage monitor coupled to the power source to detect a voltage supplied by the power source and to provide a voltage signal representative of said voltage;

    a current monitor coupled to the power source to detect a current supplied by the power source and to provide a current signal representative of said current;

    a control circuit to receive said voltage signal and said current signal, said control circuit to provide a value based on said voltage signal and said current signal according to control parameters which include a power averaging time and a power threshold; and

    , a signal attenuator coupled to the power source and the control circuit, the signal attenuator to limit said input signal based on said value, wherein an averaging coefficient (TA) is calculated by the control circuit using the power averaging time according to TA=

    -nta

    fs
    ,


    where n is a filter order, ta is the power averaging time in seconds, and fs is a sampling frequency.

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