原标题：Maxim MAX11800-803电阻型触摸屏控制方案

　　Maxim 公司的MAX11800–MAX11803是低功耗超小型电阻型触摸屏控制器,集成了I2C/SPI接口,单电源1.7V到3.6V工作.器件包括一个12位SAR ADC和复接器,主要应用在移动通信设备,PDA, GPS接收器,媒体播放器,手提仪表,POS终端,手持游戏机,汽车中心控制台.本文介绍了MAX11800–MAX11803主要特性, 功能方框图, 位置和压力测量图, 触摸检测电路和应用电路.

　　MAX11800–MAX11803: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 hostprocessor intervention. This can be used to reduce system power consumption. An on-chip FIFO is used during autonomous mode to store results and increase 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℃ to +85℃ (extended) and -40℃ to +105℃ (automotive) temperature ranges.

　　MAX11800-803主要特性:

　　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

　　MAX11800-803应用:

　　Mobile Communication Devices

　　PDAs, GPS Receivers,

　　Personal Navigation Devices, Media Players

　　Portable Instruments

　　POS Terminals

　　Handheld Games

　　Automotive Center Consoles

　　图1.MAX11800-801功能方框图

　　图2.MAX11802-803功能方框图

　　图3.位置测量图

　　图4.压力测量图

　　图5.触摸检测电路图

　　图6. MAX11800/MAX11802典型工作电路图

　　图7. MAX11801/MAX11803典型工作电路图