cy24292 Cypress Semiconductor Corporation., cy24292 Datasheet - Page 9

• Manufacturer Part Number: cy24292
• Description: Four Outputs Pci-express Clock Generator
• Manufacturer: Cypress Semiconductor Corporation.

PCB Layout Recommendations
For optimum device performance and lowest phase noise, the
following guidelines must be observed.
PCI-Express Layout Guidelines
HCSL Compatible Layout Guidelines
Table 14. Common Recommendations for Differential Routing
Table 15. Differential Routing for PCI-Express Load or Connector
Note
Document Number: 001-46142 Rev. *C
1. Each 0.01 µF decoupling capacitor must be mounted on the
2. No vias must be used between the decoupling capacitor and
3. The PCB trace to the VDD pin and the ground via must be
L1 length, route as non-coupled 50 Ω trace
L2 length, route as non-coupled 50 Ω trace
L3 length, route as non-coupled 50 Ω trace
R
R
L4 length, route as coupled microstrip 100 Ω differential trace
L4 length, route as coupled stripline 100 Ω differential trace
1. Refer to
S
T
component side of the board as close to the VDD pin as
possible.
the VDD pin.
kept as short as possible. The distance of the ferrite bead and
bulk decoupling from the device is less critical.
Figure
3.
Differential Routing
Differential Routing
Output Buffer
[1]
[1]
L1
L1
Figure 3. PCI-Express Device Routing
Rs
R
S
L2
L2
Dimension or Value
Dimension or Value
L3
Decoupling Capacitors
Decoupling capacitors of 0.01 µF must be connected between
VDD and GND as close to the device as possible. Do not share
ground vias between components. Route power from power
source through the capacitor pad, and then into the CY24292
pin.
R
4. An optimum layout is one with all components on the same
T
side of the board, minimizing vias through other signal layers
(any ferrite beads and bulk decoupling capacitors can be
mounted on the back). Other signal traces must be routed
away from the CY24292. This includes signal traces just
underneath the device, or on layers adjacent to the ground
plane layer used by the device.
1.8 to 30
0.5 max
0.2 max
0.2 max
L3
2 to 32
49.9
33
R
T
L4
L4
PCI Express Load or
Unit
Unit
inch
inch
inch
inch
inch
Ω
Ω
Connector
CY24292
Page 9 of 16
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