Abstract: A driver controller comprising a state machine for controlling transitions between a plurality of states. An output switch for providing a low impedance path to ground during transition periods. An output stage for decoupling output signal from driver amplifier during the transition periods.

Abstract: A device comprising a detector configured to receive an indication from a terminal of a connector and to determine whether the indication matches an expected result. One or more first switches are configured to connect one or more speaker transducers to the connector if the indication is false. One or more second switches are configured to connect the one or more speaker transducers to a digital output converter if the indication is true. The device can also include one or more third switches configured to connect one or more microphone elements to the connector if the indication is false, and one or more fourth switches configured to connect one or more microphones to a digital input converter if the indication is true. The input and output converters can be stand alone or part of a digital signal processor.

Abstract: An apparatus for detecting and controlling current. A current detector for generating a first value that represents an amount of current being delivered to a device. A current limit circuit for generating a second value that represents a maximum permitted current level from a current source. A current controller for controlling the amount of current drawn by the device if the first value exceeds the second value.

Abstract: A system for improved audio in a headset comprising a first headset microphone generating a first signal. A second headset microphone generating a second signal. A multiplexer coupled to the first headset microphone and the second headset microphone for multiplexing the first signal and the second signal. A power extractor for extracting power for use by one or more of the multiplexer, the first headset microphone and the second headset microphone. A demultiplexer for extracting the first signal and the second signal. A signal processor for generating a noise reduced microphone signal. An audio subsystem for receiving the noise reduced microphone signal and for generating speaker signals for a first headphone speaker and a second headphone speaker.

Abstract: An apparatus for detecting and controlling current. A current detector for generating a first value that represents an amount of current being delivered to a device. A current limit circuit for generating a second value that represents a maximum permitted current level from a current source. A current controller for controlling the amount of current drawn by the device if the first value exceeds the second value.

Abstract: A telephone line interface circuit is disclosed having intelligent line current control that can adjust to the various requirements of worldwide telephone systems (DC masks), and/or can reduce the power consumed by the interface circuit. A controller reads a voltage value and based on the theoretical model of a telephone line network, and the expected current/voltage characteristic, as dictated by the appropriate DC mask. The controller sets the line current (via an output voltage) to an optimum value and causes the line voltage to adjust so as to comply with the DC mask and/or minimize power dissipation in the circuit.

Abstract: The line interface circuit of a modem to be connected to a standard RJ11 jack of a digital PBX (Private Branch Exchange) is used along with software routines resident in the modem to detect the presence of a PBX connected to the modem. Upon going off-hook, the modem, by the software routines, determines whether the connection will harm the interface by one of several software routines. If it appears that the interface circuit may be damaged because a PBX line is present, the modem is instructed to go on-hook (hang up), or if the connection is not harmful to the interface, alerts the user that the modem is connected to a wrong jack.

Abstract: An efficient method and circuitry for transferring various levels of power across a high voltage isolation barrier. In one embodiment of the invention, a data access arrangement (DAA) is provided with system side circuitry that provides power to line side circuitry via the high voltage isolation barrier. The line side circuitry includes voltage measurement circuitry, such as an analog-to-digital converter, that periodically measures the line side supply voltage. The resultant information is transmitted across the high voltage isolation barrier to the system side circuitry, where control circuitry or a software process compares the digital representation of the measured voltage level to a predetermined value. Based on the results of this comparison, the control circuitry may alter the amount of power transferred across the high voltage isolation barrier to the line side circuitry in order to optimize power transfer efficiency.