www.SiliconStandard.com

4 of 5

SS7646

8/21/2004 Rev.2.01

APPLICATION CONSIDERATIONS

Typical Operating Circuit

SS7646

1

2

3

4

5

6

7

8

16

15

14

/CS

DCLK

DIN

DOUT

BUSY

/PENIRQ

X+

Y+

Y-

X-

2.7V to 5.5V

13

12

11

10

9

GND

Clock

Chip Select

Data In

Busy Status

Data Out

Pen

Interrupt

Battery

DC/DC

Converter

Figure 12. Typical Operation Circuit of

the SS7646

Resistive Touch Screen (4-Wire)

The 4-wire resistive touch screen consists of 2 resistive

plates that are separated by a small gap. Each of the

plates has a resistance in the range from 200 to 2000

ohms.

The screen works by applying a voltage across the X

plate or Y plate resistive networks. If a voltage is

applied, for example, between X+ and X- then a voltage

divider is formed on the X plate. When the Y plate is

touched to the X plate, a voltage will be developed on

the Y plate. By accurately measuring this voltage, the

position on the screen can be determined. The

connections between the SS7646 and the touch

screen should

be as short as possible.

Y+

X-

X+ Y-

X PLATE

Y PLATE

Electrode

Figure 13. 4-wire Resistive Touch Screen