1. Timing is both wait state and frequency dependent. In the formulas listed, WS = the number of wait states and
T = Clock Period. For 80MHz operation, T = 12.5ns.
2. Parameters listed are guaranteed by design.
To calculate the required access time for an external memory for any frequency < 80MHz, use this formula:
Top = Clock period @ desired operating frequency
WS = Number of wait states
Memory Access Time = (Top*WS) + (Top- 11.5)
A0–A15,
PS, DS
tARDD
(See Note)
tRDA
tARDA
tRDRD
tRD
tAWR
tWRWR
RD
tWRRD
tWR
tRDWR
WR
tRDD
tAD
tDOH
tWRD
tDRD
tDOS
Data In
Data Out
D0–D15
Note: During read-modify-write instructions and internal instructions, the address lines do not change state.
Figure 3-11 External Bus Asynchronous Timing
56F807 Technical Data Technical Data, Rev. 16
34
Freescale Semiconductor
FREESCALE [ Freescale ]
