Touch screen data converters

The AD7843 and AD7873 are resistive touchscreen digitizers that are suitable for touch screen devices such as personal digital assistants and point-of-sale terminals.

The AD7843 and AD7873 are resistive touchscreen digitizers that are suitable for all touch screen devices, such as personal digital assistants, handheld devices, monitors, point-of-sale terminals, and pagers.

The pin-compatible AD7843 and AD7873 integrate a 12-bit successive-approximation register (SAR) ADC architecture with low on-resistance switches for driving touch screens. The AD7873 has added functionality that includes an on-chip temperature sensor from -40º to 85ºC, direct battery and touch-pressure measurement, and an on-board reference of 2.5 V.

The AD7873 and the AD7843 consume less than 1.4 mW (max) of power with the internal reference off while operating at a throughput rate greater than 125 kSPS. The parts also feature 10-12 KeV ESD protection on analog inputs to prevent damage to critical internal system components.

Both low-power devices operate from a single 2.2 V to 5.25 V power supply. To extend battery life, the internal reference of the AD7873 can be shut down when not in use, and both devices include a power-down mode that reduces the current consumption to less than 1 µA.

The AD7843 and AD7873 are offered in a 16-lead 0.15′ quarter size outline package (QSOP) and a 16-lead thin shrink small outline package (TSSOP). The AD7843 is available for $2.15 in 1,000-piece quantities, and the AD7873 is available for $2.30 in 1,000-piece quantities.

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