TWR-K60N512-KEIL Freescale Semiconductor, TWR-K60N512-KEIL Datasheet - Page 166

• Manufacturer Part Number: TWR-K60N512-KEIL
• Description: K60N512 Keil Tower Kit
• Manufacturer: Freescale Semiconductor
• Series: Kinetisr
• Type: MCUr

Specifications of TWR-K60N512-KEIL

• Rohs Compliant: YES
• Contents: 4 Boards, Documentation, DVD
• Peak Reflow Compatible (260 C): Yes
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: Freescale Tower System, K60N512

TSI hardware implementation
17.5.1 PCB Routing and Placement
The following list includes the most important things to consider when designing touch
sensing electrodes for the TSI:
It is always important to consider ground planes. A ground plane below and around the
electrodes adds noise suppression and a reference ground for the electrodes. The problem
is that a continuous ground plane below the electrodes also increases the base
capacitance, causing the touch delta to be reduced. To work around this issue, an x-hatch
ground plane is recommended as in
out noise. Because the area is smaller, it will not increase the base capacitance as much as
a continuous plane and thus does not affect sensitivity as much.
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1. Trace width—Keep the trace width as thin as possible. 5-7 mil traces are
2. Clearance—Leave a minimum clearance of 10 mils. At the trace connection to the
3. Keep trace length as short as possible. As traces becomes longer the baseline
4. Electrode traces must be routed in a different layer from the one containing the
5. Components and traces must not be placed directly underneath the electrodes area.
recommended. The wider the traces the more base capacitance.
MCU, the pitch is lower than 10 mils, therefore use bottleneck mode.
capacitance increases and is also more susceptible to coupled noise.
electrodes.
Good results can be obtained if the number of components behind the electrodes is
minimized and running as few traces as possible.
Figure 17-8. Recommended x-hatch ground plane pattern
Kinetis Quick Reference User Guide, Rev. 0, 11/2010
Figure
17-8. The x-hatch pattern helps with filtering
Freescale Semiconductor