Compaq Computer Corporation, Inc.

Kurtis J Bowman

Thanh Thien Tran

Richard E Walker

Ronald D Noblett

Hiten N Dalal

An audio system for multimedia computer systems and method for use are provided including an audio module having speakers, a microphone and associated circuitry. The audio module is adapted to be interposed between a monitor and a monitor pedestal such that the audio module swivels and tilts in concert with the monitor. The circuitry is adapted to drive the audio module speakers and to drive only one speaker and the microphone in a speaker phone mode.

Audio system for a personal computer

A computer system having automatic speaker detection circuitry is disclosed. The typical computer system includes a central processing unit, a data input device, and a sound card. Further, there is an audio amplifier, as well as an automatic detection and selection circuit that may be within the sound card or the audio amplifier or just part of the computer system as a whole. This automatic detection selection device is able to determine an impedance load of an output device attached to the computer system, namely, a speaker system, and is able to disable the audio amplifier within the computer system upon determining the impedance load and matching that impedance load against a selected value indicating that no amplification of the signal is required for the output device. Further, an audio sound equalizer is part of the system and can be bypassed in the same manner that the audio amplifier is, namely, that particular impedance load is measured indicating that no equalization is necessary.

Multimedia speaker detection circuit

A circuit that automatically switches the power supply voltage PVDD provided to a CPU between 3.3 volts and 5 volts. The circuit detects whether the CPU installed in a socket is a 3.3-volt part or a 5-volt part by determining the state of a voltage detect sense pin provided by the socket. If the voltage detect sense pin is driven low, that indicates a 3.3-volt CPU is being used. If a 5-volt CPU is installed, the voltage detect sense pin is left floating by the CPU, which allows a pullup resistor to pull the voltage detect sense pin high. The power supply voltage provided to the CPU is regulated through a power field effect transistor (FET). The gate of the power FET is connected to the output of a voltage reference source and is coupled to a 12-volt supply signal. If the voltage detect sense pin is pulled high, the voltage reference source is turned off, allowing the 12-volt supply signal to drive the gate of the power FET. This in turn allows the power FET to pass a 5-volt supply signal to the CPU supply signal PVDD. If the voltage detect sense pin is pulled low, the voltage reference source is turned on to drive the gate of the power FET to approximately one threshold voltage above 3.3 volts. In response, the power FET passes only 3.3 volts to the CPU supply signal PVDD.

Circuit that automatically switches between supplying a microprocessor

A soft switching circuit gradually connects an audio signal to zero reference level to mute the audio signal, or connect a filter to enable the filter. A MOSFET is connected between the audio signal and the zero reference level. A resistor-capacitor circuit is connected to the gate of the MOSFET and receives the MUTE or FILTER* signal from the computer system. When the MUTE or FILTER* signal changes condition, the RC circuit provides a signal to the MOSFET gate that changes relatively gradually. Consequently, the drain-to-source resistance of the MOSFET also changes from short circuit to open circuit or vice versa relatively gradually.

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Cypress, TX, United States of America

Kurtis J Bowman