AD7843

a FEATURES 4-Wire Touch Screen Interface Specified Throughput Rate of 125 kSPS Low Power Consumption: 1.37 mW Max at 125 kSPS with VCC = 3.6 V Single Supply, VCC of 2.2 V to 5.25 V Ratiometric Conversion High-Speed Serial Interface Programmable 8- or 12-Bit Resolution Two Auxiliary Analog Inputs Shutdown Mode: 1 ␮ A max 16-Lead QSOP and TSSOP Packages APPLICATIONS Personal Digital Assistants Smart Hand-Held Devices Touch Screen Monitors Point-of-Sales Terminals Pagers X+ X– Y+ Y– Touch Screen Digitizer AD7843 FUNCTIONAL BLOCK DIAGRAM +VCC PENIRQ AD7843 PEN INTERRUPT T/H 4-TO-1 I/P MUX IN3 IN4 VREF CHARGE REDISTRIBUTION DAC COMP GND +VCC SAR + ADC CONTROL LOGIC SPORT GENERAL DESCRIPTION The AD7843 is a 12-bit successive-approximation ADC with a synchronous serial interface and low on resistance switches for driving touch screens. The part operates from a single 2.2 V to 5.25 V power supply and features throughput rates greater than 125 kSPS. The external reference applied to the AD7843 can be varied from 1 V to +VCC, while the analog input range is from 0 V to VREF. The device includes a shutdown mode that reduces the current consumption to less than 1 µA. The AD7843 features on-board switches. This coupled with low power and high-speed operation make this device ideal for battery-powered systems such as personal digital assistants with resistive touch screens and other portable equipment. The part is available in a 16-lead 0.15" Quarter Size Outline (QSOP) package ...