cy8cmbr2044 Cypress Semiconductor Corporation., cy8cmbr2044 Datasheet - Page 16

• Manufacturer Part Number: cy8cmbr2044
• Description: Capacitive Button Controllers
• Manufacturer: Cypress Semiconductor Corporation.

Layout Guidelines and Best Practices
Document Number: 001-57451 Rev. *C
Sl. No.
10
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Button shape
Button size
Button-button spacing
Button ground clearance
Ground flood – top layer
Ground flood – bottom layer
Trace length from sensor to
CapSense IC pins
Trace width
Trace routing
Via position for the sensors
Via hole size for sensor traces
No. of via on sensor trace
Distance of CapSense series
resistor from sensor pin
Distance between any
CapSense trace to ground flood
Device placement
Placement of components in two
layer PCB
Placement of components in four
layer PCB
Overlay Thickness
Overlay material
Overlay Adhesives
LED Back Lighting
Board Thickness
Category
Clearance
0.17 mm
= Button
Ground
0.5 mm
10 mil
5 mm
0 mm
Min
–
–
–
–
–
–
–
1
–
–
–
–
–
–
–
–
0.20 mm
200 mm
15 mm
10 mm
20 mil
2 mm
5 mm
Max
–
–
–
–
–
–
–
2
–
–
–
–
–
–
–
Solid round pattern, round with LED hole, rectangle
with round corners
10 mm
8 mm (Y dimension in
17)
Button ground clearance = Overlay thickness
(X dimension in
Hatched ground 7 mil trace and 45 mil grid (15%
filling)
Hatched ground 7 mil trace and 70 mil grid (10%
filling)
< 100 mm
0.17 mm (7 mil)
Traces should be routed on the non sensor side. If
any non CapSense trace crosses CapSense trace,
ensure that intersection is orthogonal
Via should be placed near the edge of the
button/slider to reduce trace length thereby
increasing sensitivity
10 mil
1
Place CapSense series resistors close to the device
for noise suppression. CapSense resistors have
highest priority; place them first
20 mil
Mount the device on the layer opposite to sensor.
The CapSense trace length between the device and
sensors should be minimum (see trace length
above)
Top layer – sensors and bottom layer – device, other
components and traces
Top layer – sensors, second layer – CapSense
traces and V
sensors), third layer – hatched ground, 
bottom layer – CapSense IC or device, other compo-
nents, and non CapSense traces
1 mm
Should be non-conductive material. Glass, ABS
plastic, formica, wood, and so on. There should be
no air gap between PCB and overlay. Use adhesive
to stick the PCB and overlay
Adhesive should be non conductive and
dielectrically homogenous. 467MP and 468MP
adhesives made by 3M are recommended
Cut a hole in the sensor pad and use rear mountable
LEDs. Refer to
Four CapSense Buttons and Four LEDs”
Standard board thickness for CapSense FR4 based
designs is 1.6 mm
Recommendations/Remarks
DD
“Example PCB Layout Design with
(avoid V
Button Layout Design
Button Layout Design
DD
CY8CMBR2044
traces below the
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