INDUSTRY-STANDARD TOUCH-SCREEN DATA CONVERTERS WITHSTAND ±15kV ESD
Note to Editor: Maxim Integrated Products' pin-compatible, industry-standard, touch-screen data converters (MXB7843 and MXB7846) offer the highest ESD protection available for such parts. ADI and TI also offer pin-compatible parts, but without this level of ESD protection. The touch-screen driver pins (and for the MXB7846, the battery voltage pins and auxiliary analog input pins) include Maxim's innovative ESD protection of up to ±8kV Contact Discharge and ±15kV Air-Gap Discharge per IEC 1000-4-2. This eliminates the need for external transient voltage suppression or absorption devices, affording significant savings to the system designer.
SUNNYVALE, CA-May 31, 2002-Maxim Integrated Products introduces the MXB7843 and MXB7846 pin-compatible, industry-standard, 4-wire touch-screen controllers with ±15kV ESD protection. The MXB7843/MXB7846 contain a low-power 12-bit sampling analog-to-digital converter (ADC) with an SPI™/QSPI™/MICROWIRE™-compatible serial interface, analog inputs, and high-speed, low on-resistance switches for driving resistive touch screens, making these parts ideal in battery-operated systems such as PDAs and other portable equipment. The MXB7846 adds additional features, including an internal 2.5V reference, an on-chip temperature sensor with ±2°C accuracy, and direct battery measurement. It also supports touch-pressure measurements without additional circuitry. All analog inputs to the MXB7843/MXB7846 are fully ESD protected up to ±8kV Contact Discharge and ±15kV Air-Gap Discharge per IEC 1000-4-2, eliminating the need for external transient-voltage suppression or absorption devices.
The MXB7843/MXB7846 interface to the host controller through a SPI™/QSPI™/
MICROWIRE™-compatible serial interface, and offer software-selectable resolution from 8 bits to 12 bits and sampling rates from 10kHz to 125kHz. Guaranteed to operate with a supply voltage from 2.5V to 5.25V they consume only 280µA at 125ksps throughput and under 2µA in the shutdown mode. The MXB7846 internal 2.5V reference may be disabled, allowing the use of an external reference or to make ratiometric measurements. The MXB7843/MXB7846 can make fully differential position measurements from the touch screen, eliminating the errors resulting from routing and switch resistance.
The MXB7843/MXB7846 are offered in 16-pin QSOP and 16-pin TSSOP packages and are guaranteed over the -40°C to +85°C temperature range. Prices start at $2.15 for the MXB7843 and $2.30 for the MXB7846 (1000-up, FOB USA).
SPI/QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
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