A/D converter with comparators and low-power detection mode...

Details A/D converter with comparators and low-power detection mode... A/D converter with comparators and low-power detection mode...

2007-01-09

2007-01-09

Wong, Albert K. (Department: 2612)

Coded data generation or conversion

Bodily actuated code generator

Including keyboard or keypad

C341S014000, C341S020000, C345S168000, C710S067000

Reexamination Certificate

active

10929731

ABSTRACT:
An apparatus and method is disclosed for providing a fast, low power consumption, detection of at least one depressed key in a resistive matrix keyboard. The common contact of each row of a resistive matrix is connected to a first input of each of a plurality of analog/digital comparators capable of switching between high and low voltage states. A common predetermined reference voltage is applied to a second input of each analog/digital comparator using a digital to analog converter. The output of a analog/digital comparator is in a first state if the voltage level applied to the first input is higher than the reference voltage, and in a second state if the voltage level applied to the first input is lower than the reference voltage. The reference voltage is varied to identify which analog/digital comparator has experienced a change of state.

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patent: 6577250 (2003-06-01), Yee

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