
MOTOROLA
M68020 USERS MANUAL
10-9
AC ELECTRICAL CHARACTERISTICSREAD AND WRITE CYCLES
(Continued)
16.67 MHz
20 MHz
25 MHz
**
33.33 MHz
Num.
Characteristics
Min
Max
Min
Max
Min
Max
Min
Max
Unit
29
AS, DS Negated to Data-In Invalid
(Data-In Hold Time)
0
0
00ns
29A
AS, DS Negated to Data-In
(High Impedance)
60
50
40
30
ns
30
Clock Low to Data-In Invalid
(Data-In Hold Time)
15
15
10
10
ns
312
DSACK
Asserted to Data-In Valid
50
43
32
17
ns
31A3
DSACK
Asserted to DSACK Valid
(
DSACK
Asserted Skew)
15
10
10
10
ns
32
RESET Input Transition Time
1.5
1.5
1.5
1.5
Clks
33
Clock Low to
BG Asserted
0
30
0
25
0
20
0
20
ns
34
Clock Low to
BG Negated
0
30
0
25
0
20
0
20
ns
35
BR Asserted to BG Asserted (RMC Not
Asserted)
1.5
3.5
1.5
3.5
1.5
3.5
1.5
3.5
Clks
*37
BGACK Asserted to BG Negated
1.5
3.5
1.5
3.5
1.5
3.5
1.5
3.5
Clks
*37A6 BGACK Asserted to BR Negated
0
1.5
0
1.5
0
1.5
0
1.5
Clks
39
BG Width Negated
90
75
60
50
ns
39A
BG Width Asserted
90
75
60
50
ns
*40
Clock High to
DBEN Asserted (Read)
0
30
0
25
0
20
0
15
ns
*41
Clock Low to
DBEN Negated (Read)
0
30
0
25
0
20
0
15
ns
*42
Clock Low to
DBEN Asserted (Write)
0
30
0
25
0
20
0
15
ns
*43
Clock High to
DBEN Negated (Write)
0
30
0
25
0
20
0
15
ns
*44
R/
W Low to DBEN Asserted (Write)
15
10
10
5ns
*455
DBEN Width Asserted
Read
Write
60
120
50
100
40
80
30
60
ns
46
R/
W Width Valid (Write or Read)
150
125
100
75
ns
47A
Asynchronous Input Setup Time
5
5
55ns
47B
Asynchronous Input Hold Time
15
15
10
10
ns
484
DSACK
Asserted to BERR, HALT Asserted
30
20
18
15
ns
53
Data-Out Hold from Clock High
0
0
00ns
55
R/
W Valid to Data Bus Impedance Change
30
25
20
20
ns
56
RESET Pulse Width (Reset Instruction)
512
512
512
512
Clks
57
BERR Negated to HALT Negated (Rerun)
0
0
00ns
*5810 BGACK Negated to Bus Driven
1
1
11
Clks
5910
BG Negated to Bus Driven
1
1
11
Clks
*This specification does not apply to the MC68EC020.
**These specifications represent an improvement over previously published specifications for the 25-MHz MC68020
and are valid only for product bearing date codes of 8827 and later.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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