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MCF5272 ColdFire
®
Integrated Microprocessor User’s Manual, Rev. 3
Freescale Semiconductor
B-1
Appendix B
Buffering and Impedance Matching
When required:
•
SDRAM and a large number of external peripherals are required for a particular system
configuration.
•
Some peripherals may have excessive input capacitance.
•
Minimize signal reflections at higher clock speeds.
•
Minimize capacitive loading on signals to SDRAMs.
•
Operation of MCF5272 at highest frequencies, i.e. 66MHz, requires clean signals to ensure setup
and hold times are met and to minimize EMC noise in terms of overshoot and undershoot of
signals.
What to do:
•
Add buffers on address and control signals shared by SDRAM and other peripherals.
•
NEVER put buffers between the MCF5272 device and the SDRAMs.
•
Put termination resistors as close as possible to outputs.
•
Or use buffers that have integral termination resistors.
Содержание MCF5272 ColdFire
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