Low-power on-chip headset switch detection

Details Low-power on-chip headset switch detection Low-power on-chip headset switch detection

2006-07-26

2011-12-13

Chin, Vivian (Department: 2614)

Electrical audio signal processing systems and devices

Directive circuits for microphones

C381S123000, C381S120000

Reexamination Certificate

active

08077878

ABSTRACT:
An integrated circuit within a cellular telephone has a wake mode and a sleep mode. In the wake mode, a voltage regulator supplies a regulated voltage onto a MIC BIAS terminal. This voltage biases a microphone of a headset/microphone accessory that is coupled to the cellular telephone. If the user presses a switch on the accessory, then a large current is drawn out of the MIC BIAS terminal. This switch press condition is detected by an ADC within the integrated circuit. In the sleep mode, the regulator and ADC are disabled to conserve power. A novel switch detect circuit supplies a current out of the MIC BIAS terminal at an unregulated voltage. If the user presses the switch, then the current supplied from the MIC BIAS terminal increases. This switch press condition is detected over temperature, voltage and process conditions by a special inverter in the switch detect circuit.

REFERENCES:
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International Search Report—PCT/US07/074525—International Search Authority—European Patent Office—Dec. 13, 2007.
Written Opinion—PCT/US07/074525, International Search Authority—European Patent Office—Dec. 13, 2007.

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