VSC8201DL

Rev. 1.6.3 - 9/29/04

VITESSE - CONFIDENTIAL & PROPRIETARY - DO NOT COPY WITHOUT PERMISSION

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Since all PCB designs yield unique noise coupling behavior, not all ferrite beads or decoupling capacitors may be needed for every

design. For this reason, it is recommended that system designers provide and option to replace the ferrite beads with zero-ohm resistors,

once thorough evaluation of system performance is completed.

PCB Chassis ground Region

To isolate the board from the ESD events and to provide a common-mode noise ground path, a separate chassis ground region should

be allocated. This should provide an electrical connection to the external chassis and the shield ground to discharge common-mode

noise through a 75-ohm resistor and a single 1000pF 2kV capacitor. See “VSC8201 System Schematic” in the datasheet.

Figure 4: Ground Plane Layout

Key points

•

The chassis ground and the PCB ground should have as much separation as possible. 45 mils or greater is recommended.

•

There should be no power or ground plane beneath the primary and secondary coils of the transformer.