MK712

I C R O C LOC K Description The MK712 Touch Screen Controller IC provides all the screen drive, A to D converter and control circuits to easily interface to 4-wire analog resistive touch screens. The IC continually monitors the screen waiting for a touch. In this mode, the supply current is typically 0.5µA. When the screen is touched, the IC performs analog to digital conversions to determine the location of the touch, stores the X and Y locations in the registers, and issues an interrupt. This process is repeated up to 197 times per second until no further screen touches are detected, at which time the low current mode is resumed. MK712 Touch Screen Controller Features Fully integrated, lowest power solution Low standby current of 0.5µA (typical) at 5.0V Active current while converting less than 10 mA Resolves 350 dots/inch on 10.5” display Maximum speed of 197 points/second Ratiometric conversion may eliminate screen calibration Automatically wakes up and goes back to standby 3.3V or 5V supply 12 bit A/D converter Simplifies the writing of software for touch screens Extended temperature range available Capacitors are the only external components required Touch screen is directly driven - no external transistors are required Programmable conversion rate A to D Converter is monotonic Parallel interface See the MK715 for a serial interface Block Diagram D0-D7 A0-A2 CS RD WR 8 3 REGISTERS STATUS LOW STATUS HIGH X-LOW X-HIGH Y-LOW Y-HIGH CON...