CY8C20121 CYPRESS [Cypress Semiconductor], CY8C20121 Datasheet - Page 23

• Manufacturer Part Number: CY8C20121
• Description: CapSense Express-One Button and Two Button Capacitive Controllers
• Manufacturer: CYPRESS [Cypress Semiconductor]

8. Layout Guidelines and Best Practices
Document Number: 001-53516 Rev. **
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No.
Sl.
Button Shape
Button Size
Button Button Spacing
Button Ground Clearance
Ground Flood - Top Layer
Ground Flood - Bottom Layer
Trace Length from Sensor to
PSoC - Buttons
Trace Width
Trace Routing
Via Position for the Sensors
Via Hole Size for Sensor Traces
No. of Via on Sensor Trace
CapSense Series Resistor
Placement
Distance between any
CapSense Trace to Ground
Flood
Device Placement
Placement of Components in 2
Layer PCB
Placement of Components in 4
Layer PCB
Overlay Thickness - Buttons
Overlay Material
Overlay Adhesives
LED Back Lighting
Board Thickness
Category
5 mm
= Button
Ground
Clearance
0.5 mm
0.17 mm
1
10 mil
0 mm
Min
PRELIMINARY
15 mm
2 mm
200 mm
0.20 mm
2
10mm
20 mil
2 mm
Max
Solid round pattern, round with LED hole, rectangle with
round corners
10 mm
8 mm
Button ground clearance = Overlay Thickness
Hatched ground 7 mil trace and 45 mil grid (15% filling)
Hatched ground 7 mil trace and 70 mil grid (10% filling)
< 100 mm.
Traces should be routed on the non sensor side. If any non
CapSense trace crosses CapSense trace, ensure that inter-
section is orthogonal.
reduce trace length thereby increasing sensitivity.
10 mil
suppression.CapSense resistors have highest priority place
them first.
Mount the device on the layer opposite to sensor. The
CapSense trace length between the device and sensors
should be minimum
Top layer-sensor pads and bottom layer-PSoC, other compo-
nents and traces.
Top layer-sensor pads, second layer – CapSense traces,
third layer-hatched ground, bottom layer- PSoC, other
components and non CapSense traces
1 mm
Should to be non conductive material. Glass, ABS Plastic,
Formica
Adhesive should be non conductive and dielectrically homog-
enous. 467MP and 468MP adhesives made by 3M are
recommended.
Cut a hole in the sensor pad and use rear mountable LEDs.
Refer
Buttons and Two LEDs
Standard board thickness for CapSense FR4 based designs
is 1.6 mm.
0.17 mm (7 mil)
Via should be placed near the edge of the button/slider to
1
Place CapSense series resistors close to PSoC for noise
20 mil
Example PCB Layout Design with Two CapSense
Recommendations/Remarks
CY8C20111, CY8C20121
on page 26.
Page 23 of 34
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