WM9713 datasheet(60/111 Pages) WOLFSON

Part #	WM9713

Description	AC 97 AUDIO TOUCHPANEL CODEC

PDF	111 Pages

Scroll/Zoom	100%

Manufacturer	WOLFSON [Wolfson Microelectronics plc]

Direct Link	http://www.wolfsonmicro.com

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60 / 111 page

WM9713L

Preliminary Technical Data

PTD, March 2004, Rev 2.2

Figure 17 X Co-ordinate Measurement on 4-wire Touchpanel

For an X co-ordinate measurement, the X+ pin is internally switched to VDD and X- to GND. The X

plate becomes a potential divider, and the voltage at the point of contact is proportional to its X co-

ordinate. This voltage is measured on the Y+ and Y- pins, which carry no current (hence there is no

voltage drop in RY+ or RY-).

Due to the ratiometric measurement method, the supply voltage does not affect measurement

accuracy. The voltage references VREF+ and VREF- are taken from after the matrix switches, so

that any voltage drop in these switches has no effect on the ADC measurement.

Figure 18 Y Co-ordinate Measurement on 4-wire Touchpanel

Y co-ordinate measurements are similar to X co-ordinate measurements, with the X and Y plates

interchanged.

Figure 19 Pen Down Detection on 4-wire Touchpanel

WM9713 Datasheet(PDF) 60 Page - Wolfson Microelectronics plc