CY2280 Cypress Semiconductor, CY2280 Datasheet - Page 9

• Manufacturer Part Number: CY2280
• Description: 100-MHz Pentium II Clock Synthesizer/Driver with Spread Spectrum for Mobile or Desktop PCs
• Manufacturer: Cypress Semiconductor

Application Circuit
Application Information
Clock traces must be terminated with either series or parallel termination, as is normally done.
Document #: 38-07207 Rev. *A
Summary
• A parallel-resonant crystal should be used as the reference to the clock generator. The operating frequency and C
• Surface mount, low-ESR, ceramic capacitors should be used for filtering. Typically, these capacitors have a value of 0.1 F.
• The value of the series terminating resistor satisfies the following equation, where Rtrace is the loaded characteristic imped-
• Footprints must be laid out for optional EMI-reducing capacitors, which should be placed as close to the terminating resistor
• A Ferrite Bead may be used to isolate the Board V
• If a Ferrite Bead is used, a 10 F–22 F tantalum bypass capacitor should be placed close to the Ferrite Bead. This capacitor
this crystal should be as specified in the data sheet. Optional trimming capacitors may be needed if a crystal with a different
C
In some cases, smaller value capacitors may be required.
ance of the trace, Rout is the output impedance of the clock generator (specified in the data sheet), and Rseries is the series
terminating resistor.
as is physically possible. Typical values of these capacitors range from 4.7 pF to 22 pF.
greater than 50 impedance at the clock frequency, under loaded DC conditions. Please refer to the application note “Layout
and Termination Techniques for Cypress Clock Generators” for more details.
prevents power supply droop during current surges.
LOAD
is used. Footprints must be laid out for flexibility.
Rseries > Rtrace – Rout
DD
from the clock generator V
DD
island. Ensure that the Ferrite Bead offers
CY2280
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of