MK712

Touch Screen Controller

MDS 712 I

1

Revision 100899

Printed 11/16/00

Integrated Circuit Systems, Inc.•525 Race St.•San Jose•CA•95126•(408)295-9800tel•www.icst.com

I C R O

Pin Assignment

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.

Block Diagram

Description

Features

XH

XL

• 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

YH

YL

(14.318 MHz)

12 Bit A/D,

Screen Driver

and

Controller

D0-D7

A0-A2

CS

STATUS LOW

STATUS HIGH

X-LOW

X-HIGH

CONTROL

0

1

2

3

4

INT

TOUCH

CLKIN

YH

INT

XH

XL

VDD

VDD

TOUCH

YL

GND

CS

NC

GND

D0

GND

D1

D5

VDD

D3

D4

D2

D6

D7

A2

A0

A1

CLKIN

REGISTERS

RD

Y-LOW

Y-HIGH

RATE

5

6

7

WR

RD

WR

1

14

2

3

4

5

6

7

8

9

10

11

12

13

28

15

27

26

25

24

23

22

21

20

19

18

17

16

8

3