General Description

The MXB7846 is an industry-standard 4-wire touchscreen controller. It contains a 12-bit sampling analogto-digital converter (ADC) with a synchronous serial interface and low on-resistance switches for driving resistive touch screens. The MXB7846 uses an internal +2.5V reference or an external reference. The MXB7846 can make absolute or ratiometric measurements. In addition, this device has an on-chip temperature sensor, a battery-monitoring channel, and has the ability to perform touch-pressure measurements without external components. The MXB7846 has one auxiliary ADC input. All analog inputs are fully ESD protected, eliminating the need for external TransZorb™ devices.

Features

♦ ESD-Protected ADC Inputs

    ±15kV IEC 61000-4-2 Air-Gap Discharge

    ±8kV IEC 61000-4-2 Contact Discharge

♦ Pin Compatible with MXB7843

♦ +2.375V to +5.25V Single Supply

♦ Internal +2.5V Reference

♦ Direct Battery Measurement (0 to 6V)

♦ On-Chip Temperature Measurement

♦ Touch-Pressure Measurement

♦ 4-Wire Touch-Screen Interface

♦ Ratiometric Conversion

♦ SPI™/QSPI™, 3-Wire Serial Interface

♦ Programmable 8-/12-Bit Resolution

♦ Auxiliary Analog Input

♦ Automatic Shutdown Between Conversions

♦ Low Power (External Reference)

    270µA at 125ksps

    115µA at 50ksps

    25µA at 10ksps

    5µA at 1ksps

    2µA Shutdown Current

Applications

    Personal Digital Assistants

    Portable Instruments

    Point-of-Sales Terminals

    Pagers

    Touch-Screen Monitors

    Cellular Phones