Low-Power, Ultra-Small Resistive Touch-Screen Controllers with I²C/SPI Interface

The MAX11800–MAX11803 low-power touch-screen controllers operate from a single supply of 1.70V to 3.6V, targeting power-sensitive applications such as handheld equipment. The devices contain a 12-bit SAR ADC and a multiplexer to interface with a resistive touch-screen panel. A digital serial interface provides communications.

The MAX11800–MAX11803 include digital preprocessing of the touch-screen measurements, reducing bus loading and application-processor resource requirements. The included smart interrupt function generator greatly reduces the frequency of interrupt servicing to the devices. The MAX11800–MAX11803 enter low-power modes automatically between conversions to save power, making the devices ideal for portable applications.

The MAX11800/MAX11801 offer two modes of operation: direct and autonomous. Direct mode allows the application processor to control all touch-screen controller activity. Autonomous mode allows the MAX11800/MAX11801 to control touch-screen activity, thereby freeing the application processor to perform other functions. In autonomous mode, the devices periodically scan the touch screen for touch events without requiring host-processor intervention. This can be used to reduce system power consumption. An on-chip FIFO is used during autonomous mode to store results, increasing effective data throughput and lower system power.

The MAX11800–MAX11803 support data-tagging, which records the type of measurement performed; X, Y, Z1, or Z2, and the type of touch event; initial touch, continuing touch, or touch release.

The MAX11800/MAX11802 support the SPI™ serial bus. The MAX11801/MAX11803 support the I²C serial bus. The MAX11800–MAX11803 are available in 12-pin TQFN and 12-pin WLP packages, and are specified over the -40°C to +85°C (extended) and -40°C to +105°C (automotive) temperature ranges.

Applications

* Automotive Center Consoles * Devices, Media Players * Handheld Games * Mobile Communication Devices * PDAs, GPS Receivers, Personal Navigation * Portable Instruments * POS Terminals

* 4-Wire Touch-Screen Interface

* X/Y Coordinate and Touch Pressure Measurement

* Ratiometric Measurement

* 12-Bit SAR ADC

* Single 1.7V to 3.6V Supply

* Two Operating Modes—Direct and Autonomous

* Data Tagging Provides Measurement and Touch Event Information

* Data Filtering Provides Noise Reduction

* Aperture Mode Provides Spatial Filtering

* Digital Processing Reduces Bus Activity and Interrupt Generation

* Programmable Touch-Detect Pullup Resistors

* Auto Power-Down Control for Low-Power Operation

* 25MHz SPI Interface (MAX11800/MAX11802)

* 400kHz I²C Interface (MAX11801/MAX11803)

* 1.6mm x 2.1mm, 12-Pin WLP and 4mm x 4mm, 12-Pin TQFN

* Low-Power Operation

* 343µW at VDD = 1.7V, 34.4ksps

* 888µW at VDD = 3.3V, 34.4ksps

* ESD Protection

* ±4kV HBM

* ±8kV HBM (X+, X-, Y+, Y-)

* ±1kV CDM

* ±200V MM