Freescale Semiconductor, Inc.
Appendix: CGM Practical Aspects
• Mount the PLL filter and oscillator components as close to the
MCU as possible.
• Do not allow the EXTAL and XTAL signals to interfere with the
XFC node. Keep these tracks as short as possible.
• Do not cross the CGM signals with any other signal on any level.
• Remember that the reference voltage for the XFC filter is
VDDPLL.
• As the return path for the oscillator circuitry is VSSPLL, it is
extremely important to CONNECT VSSPLL to VSS even if the
PLL is not to be powered. Surface mount components reduce the
susceptibility of signal contamination.
• Ceramic resonators with built-in capacitors are available. This is
an interesting solution because the parasitic components involved
are minimized due to the close proximity of the resonating
elements.
Advance Information
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68HC(9)12D60 — Rev 4.0
Appendix: CGM Practical Aspects
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