AR1100BRD Microchip Technology, AR1100BRD Datasheet - Page 29

• Manufacturer Part Number: AR1100BRD
• Description: 58T8314
• Manufacturer: Microchip Technology

Specifications of AR1100BRD

• Features: Automatically Detects Communication Type, Dynamic Rise Time And Sampling Capability
• Application Sub Type: Touch-Screen Controllers
• Kit Application Type: Communication & Networking

mTouch™ AR1100 User’s Guide
Chapter 7. Touch Screen Selection
The 4 and 8-wire touch screens are typically produced with higher resistance
transparent conductive film (ITO Indium Tin Oxide) than 5-wire touch screens. Most
often, touch screen resistance falls within 100-400 Ohm per square. Because 4 and
8-wire touch screens typically have a higher resistance than 5-wire sensors, you will
find most battery-powered applications using this technology. You will also find that 4
and 8-wire touch screens are more linear than 5-wire ones.
The 5-wire touch screens are typically more mechanically durable (top sheet does not
need to be linear) and are less affected by environmental variation. 5-wire touch
screens come in a wide variety of sheet resistance. In some cases, because of the
5-wire construction, the resistance may be lower than the 50 Ohm specification. While
these touch screens require more power to drive them, this does not imply poor quality.
Once resistance drops below an optimum level, so does the resolution. In contrast, as
resistance increases, depending upon the construction, contact resistance begins to
negatively affect the touch screen’s performance. The negative effect of a high or low
resistance touch screen can be managed by properly implementing the correct circuit.
It should be understood that extremes in either direction will negatively influence the
performance of any efficient circuit design. In order to maximize efficiency and
performance, a higher resistance, linear, environmentally stable touch screen is
recommended.
Your product design requirements will help you identify the touch screen technology
and construction that will best suit your application. Please contact Microchip
Technology Inc. for more unbiased touch screen material science information and a list
of recommended Microchip controller designs to fit your application.
 2011 Microchip Technology Inc.
DS41604A-page 29