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
CONTROL
RATE
0
1
2
3
4
5
6
7
Pin Assignment
NC
INT
TOUCH
VDD
VDD
XH
XL
YH
YL
GND
GND
WR
RD
CS
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
D0
D1
D2
D3
D4
D5
VDD
GND
D6
D7
CLKIN
A0
A1
A2
CLKIN
(14.318 MHz)
INT
TOUCH
12 Bit A/D,
Screen Driver
and
Controller
XH
XL
YH
YL
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
ICS [ INTEGRATED CIRCUIT SYSTEMS ]
