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I?C keyboard controller supports QWERTY

Posted: 27 Oct 2009 ?? ?Print Version ?Bookmark and Share

Keywords:keyboard controller? QWERTY keypad? processor?

TCA8418 keyboard controller

Texas Instruments Inc. introduces a key scan device that can generate an interrupt output signal using a three-key combination such as CTRL-ALT-DEL, which frees up the processor from scanning the keys for presses and releases, saving power and bandwidth. The TCA8418 supports applications such as smart phones, multimedia handsets, personal digital assistants and mobile Internet devices.

The features of the TCA8418 include an oscillator that debounces at 50?s and maintains a 10byte FIFO of key-press and key-release events, which can store up to 10 keys with overflow wrap capability. It has an interrupt (/INT) output that can be configured to alert key presses and releases, either as they occur or at maximum rate. The power supply voltage operating range of 1.65V to 3.6V allows for glueless interface to today's most advanced processors.

The chip has 18 GPIOs can be configured into eight inputs and ten outputs, which supports an 8 x 10 key array (80 buttons) through the I?C interface. Thus, it supports QWERTY keypad operation. At the same time it can be used with a processor that has limited GPIOs, and is compatible with a variety of advanced processors including many of TI's OMAP 3 applications processors. Plus, the chip's low standby (idle) current consumption of 3?A extends battery life in portable devices.

The TCA8418 is available now in a 4mm x 4mm QFN package and is priced at $1.20 in quantities of 1,000. A 2mm x 2mm WCSP version will be available in Q1 10, offering a reduction of 75 percent board space over competitive devices.

For application notes on controllers click here.

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