Fairchild Semiconductor Corporation

Tony Cheng Han Lee

Shawn Barden

Seth M Prentice

Emma Wang

Ricky Li

The disclosure provides a button-press detection and filtering method, related circuit, and button-press detection chip for a external device. A button-press signal from a wire control apparatus is coupled to the button-press detection chip for the external device. The button-press detection chip for the external device can digitally sample the button-press signal through the filter circuit and outputs a digital logic signal corresponding to a button to an audio codec according to the sampling result. The audio codec can determine a pressed button according to the digital logic signal and performs a corresponding function. With the solutions of the disclosure, a noise interference signal in a button-press signal may be avoided and a pressed button may be accurately detected, without using a dedicated chip or complex software codes in a wire control apparatus and an electronic device.

Button-press detection and filtering

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, a switching device and method configured to receive a signal at a signal input, to provide the signal at an output in a first state without an applied voltage at a first control input, and to isolate the signal from the output in a second state with an applied voltage at the first control input. In an example, the switching device can include first, second, and third transistors, wherein the source of the first transistor is coupled to the drain of the second transistor and to the gate of the third transistor, wherein the signal input is coupled to the drain of the first transistor and to the drain of the third transistor, and wherein the output is coupled to the source of the third transistor.

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South Portland, ME, United States of America

Tony Cheng Han Lee