MPC555 / MPC556
CLOCK AND BOARD GUIDELINES
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
E-8
The voltage to the VDDSYN pin should be well regulated and the pin should be pro-
vided with an extremely low impedance path from the VDDSYN filter to the VDDSYN
pad.
The VSSSYN pin should be provided with an extremely low impedance path in the
board. All the filters for the supplies should be located as close as possible to the chip
package. It is recommended to design individual VSSSYN plane to improve VSSSYN
quietness.
E.4.2 Grounding/Guarding
The traces from the oscillator pins and PLL pins of the MPC555 / MPC556 should be
guarded from all other traces to reduce crosstalk. It can be provided by keeping other
traces away from the oscillator circuit and placing a ground plane around the compo-
nents and traces.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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