Dram Timing - Motorola DSP56367 User Manual

Specifications
External Memory Expansion Port (Port A)
3.10.2

DRAM TIMING

The selection guides provided in Figure 3-11 and Figure 3-14 should be used for primary
selection only. Final selection should be based on the timing provided in the following tables.
As an example, the selection guide suggests that 4 wait states must be used for 100 MHz
operation when using Page Mode DRAM. However, by using the information in the
appropriate table, a designer may choose to evaluate whether fewer wait states might be used
by determining which timing prevents operation at 100 MHz, running the chip at a slightly
lower frequency (e.g., 95 MHz), using faster DRAM (if it becomes available), and control
factors such as capacitive and resistive load to improve overall system performance.
DRAM Type
(t ns)
RAC
100
80
70
60
50
Figure 3-11 DRAM Page Mode Wait States Selection Guide
3-22
Note: This figure should be use for primary selection.
For exact and detailed timings see the
following tables.
40 66 80
1 Wait States
2 Wait States
DSP56367
Chip Frequency
(MHz)
120
100
3 Wait States
4 Wait States
AA047
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