MK715

MK715 Touch Screen Controller General Description The MK715 Touch Screen Controller IC provides all the screen drive, Analog to Digital converter (ADC) and control circuits to easily interface to 4-wire analog resistive touch screens. It also includes a general purpose A to D converter and a clock synthesizer. The IC continually monitors the screen waiting for a touch. In this mode, the supply current is typically 4µA. 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 303 times per second until no further screen touches are detected, at which time the low current mode is resumed. The device has a general purpose input into the 10-bit ADC, allowing for the measurement of other inputs such as battery voltage. The MK715 can be powered from a 3.3V supply, and uses an inexpensive 32.768kHz watch crystal as the input reference. An internal Phase-Lock Loop clock synthesizer provides the high speed clock for the ADC, and the option to have a clock output to drive other digital chips in the system. The tiny package is the same body size as the 14 pin SOIC, with 25 mil spacings on the leads. Features • • • • • • • • • • • • • • • • • • Tiny 20 pin SSOP (150 mil body) 4 microamp standby current Less than 3mA active current at 3.3V, including screen drive Touch pressure can be measured One or two general purpose A to D in...