Fairchild Semiconductor Corporation

Farichild Semiconductor Corporation

Seth M Prentice

Julie Lynn Stultz

Shawn Barden

John R Turner

Yongliang Li

Oscar W Freitas

Christian Klein

Tony Cheng Han Lee

Graham L S Connolly

Wonsoo Moon

Jim Morra

This document discusses, among other things, systems and methods to reduce power use of an accessory detection device. The accessory detection device can be configured to be coupled to a mobile device having an audio jack configured to be coupled to a mobile device accessory having a send/end key. In an example, the accessory detection device can include a comparator and a switch. The comparator can be configured to receive mobile device accessory information from the mobile device accessory and to determine activation of the send/end key using the received mobile device accessory information. The switch can be configured to receive connection information indicative of mobile device accessory connection to the audio jack and to isolate a reference input of the comparator from a supply voltage using the connection information, for example, to reduce leakage current.

Enable and disable comparator voltage reference

This document discusses, among other things, an advanced slave circuit and method configured to transfer power from a master device to a battery through an advanced slave circuit in a first mode using a load switch in a first state, to isolate the battery from the master device using the load switch in a second state, and to selectively couple a microphone to the master device using the advanced slave circuit in a second mode using a microphone switch.

Audio accessory communication with active noise cancellation

This document discusses, among other things, a detection system configured to identify a type of a pole of a four-pole audio jack using first and second comparators. The detection system can include a bias circuit configured to bias a detection input coupled to the pole, and first and second comparators configured to compare the detection input to respective first and second thresholds to provide an indication of the type of the pole.

Audio jack detection circuit

This application discusses a system that can include a master device and a slave device coupled to the master device via an audio jack connector. In an example, the master device and the slave device can be configured to exchange information via a single conductive path of the audio jack connector using a digital communication protocol. The single conductive path can be configured to conduct audio signals of an audio transducer and the slave device can include a depletion-mode transistor to complete a circuit including the audio transducer and the single conductive path in a first state, and to isolate the audio transducer from the single conductive path in a second state.

Audio jack system

This document discusses, among other things, an audio jack detection switch configured to be coupled to first and second GND/MIC terminals of an audio jack, wherein the audio jack detection switch includes a detection circuit configured to measure an impedance on the first and second GND/MIC terminals and identify each GND/MIC terminal as either a GND pole or a MIC pole using the measured impedance, and wherein the audio jack detection switch includes a switch configured to automatically couple an identified MIC pole to a MIC connection and to automatically couple an identified GND pole to a GND connection using information from the detection circuit.

MIC/GND detection and automatic switch

This document discusses, among other things, a MIC audio noise filtering system configured to detect MIC audio noise at a pole of a four-pole audio jack using first and second comparators. The MIC audio noise detection system can include first and second comparators configured to compare a value of the pole to respective first and second thresholds and to provide an output indicative of the comparisons and a detection circuit configured to count changes in the output over a first period of time and to detect MIC audio noise at the pole of the four-pole audio jack using the count.

MIC audio noise filtering

This document discusses, among other things, a GSM noise detection system configured to detect GSM noise at a pole of a four-pole audio jack using first and second comparators. The GSM noise detection system can include first and second comparators configured to compare a value of the pole to respective first and second thresholds and to provide an output indicative of the comparisons and a detection circuit configured to count changes in the output over a first period of time and to detect GSM noise at the pole of the four-pole audio jack using the count.

Detection and GSM noise filtering

This document discusses, among other things, systems and methods including a depletion-mode switch configured to pass an audio signal from an input to an output in a low-impedance state when a power source is below a threshold and to isolate the input from the output in a high-impedance state when the power source is above the threshold and a noise-cancelation circuit configured to receive the audio signal from the input and to provide a modulated audio signal at the output when the power source is above the threshold.

Noise-canceling headphone depletion-mode switch

An apparatus comprises a first connector, a second connector, a detection circuit and a logic circuit. The first connector and the second connector are configured for electrical communication with first and second conducting terminals, respectively, of an audio jack plug. The detection circuit is configured to apply a first value of current to the first connector, and apply a second value of current to the second connector. The logic circuit is configured to generate an indication that the audio jack plug is fully inserted according to a logic level detected at the second connector when electrical ground is detected at the first connector.

Accessory detection circuit with improved functionality

This document discusses, among other things, an audio jack detection circuit configured to be coupled to an audio jack receptacle of an external device. The audio jack detection circuit configured to receive to receive audio jack receptacle information, to disable an oscillator when the audio jack receptacle information indicates that the audio jack receptacle is empty, and to enable the oscillator when the audio jack receptacle information indicates that the audio jack receptacle includes an audio jack.

Audio jack detection and configuration

This document provides apparatus and methods for providing low-power operation of an interface circuit during an interval when a port of the interface circuit is in an uncoupled state.

Audio jack reset

Apparatus and method are described, illustratively in an LVLS master/slave system, for detecting a circuit failure, shutting down the system as if a normal power down function has occurred, but restarting the system. Signals, including power and ground lines are monitors, mal-functions detected and the apparatus put into a power down sequence. Illustratively in the LVLS system, driving a signal line to either the power or ground rails is used as a signal to the apparatus to enter the power down sequence. The present invention, after a programmable time, then drives the signal line to the opposite rail thereby signaling the system to restart&#x2014;a wake up mode. After a programmable time, the signal line is released and the system resumes normal operation.

Method and apparatus for detecting and recovering from external electrical disturbances

A system reduces a received RF signal from EMI generated by a digital electronic system that includes a clock. In the present invention the clock frequency, that generates signals and strobes data out, is purposely changed or modulated, by, illustratively, driving the power node of the clock. The typical filter circuit between the clock power node and the power supply is used to advantage in that the filter impedance allows a buffer to more easily drive the clock power node since the low impedance of the power supply is isolated by the filter circuit. The changing of the clock frequency spreads the EMI RF harmonics over a spectrum so that any harmonics received by an RF receiver will be short lived and therefore of small magnitude.

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Auburn, ME, United States of America

Seth M Prentice