CY24293 Cypress Semiconductor, CY24293 Datasheet - Page 4

• Manufacturer Part Number: CY24293
• Description: Two Outputs PCI-Express Clock Generator
• Manufacturer: Cypress Semiconductor

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PCB Layout Recommendations
For optimum device performance and the lowest phase noise,
the following guidelines must be observed:
PCI-Express Layout Guidelines
HCSL Compatible Layout Guidelines
Table 5. Common Recommendations for Differential Routing
Table 6. Differential Routing for PCI-Express Load or Connector
Note
Document Number: 001-46117 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 50Ω trace
L2 length, route as non-coupled 50Ω trace
L3 length, route as non-coupled 50Ω trace
R
R
L4 length, route as coupled microstrip 100Ω differential trace
L4 length, route as coupled stripline 100Ω 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. Distance of the ferrite bead and bulk
decoupling from the device is less critical.
Figure
3.
Output Buffer
Differential Routing
Differential Routing
L1
L1
[1]
[1]
Figure 3. PCI-Express Device Routing
Rs
R
S
L2
L2
L3
R
Decoupling Capacitors
The 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
the power source through the capacitor pad and then into the
CY24293 pin.
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 CY24293. This includes signal traces just
underneath the device, or on layers adjacent to the ground
plane layer used by the device.
Dimension or Value
Dimension or Value
L3
R
T
1.8 to 30
0.5 max
0.2 max
0.2 max
2 to 32
L4
49.9
L4
33
PCI Express Load or
Connector
Unit
Unit
inch
inch
inch
inch
inch
Ω
Ω
CY24293
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