MOTOROLA
M68040 USER’S MANUAL
B-13
MC68EC040 REV2.3 (01/31/2000)
B.7.5 Clock AC Timing Specifications (see Figure B-7)
*Specication value at maximum frequency of operation.
20 MHz
25 MHz
33 MHz
40 MHz
Unit
Num
Characteristic
Min
Max
Min
Max
Min
Max
Min
Max
Frequency of Operation
16.67
20
16.67
25
16.67
33.3
20
40
MHz
1
PCLK Cycle Time
25
30
20
30
15
30
12.5
25
nS
2
PCLK Rise Time
—
1.7
—
1.7
—
1.7
—
1.5
nS
3
PCLK Fall Time
—
1.6
—
1.6
—
1.6
—
1.5
nS
4
PCLK Duty Cycle Measured at
1.5 V
48
52
47.5
52.5
46.67
53.33
46.00
54.00
%
4a*
PCLK Pulse Width High
Measured at 1.5 V
12
13
9.5
10.5
7
8
5.75
6.75
nS
4b*
PCLK Pulse Width Low
Measured at 1.5 V
12
13
9.5
10.5
7
8
5.75
6.75
nS
5
BCLK Cycle Time
50
60
40
60
30
60
25
50
nS
6,7
BCLK Rise and Fall Time
—4—4—3—3
nS
8
BCLK Duty Cycle Measured at
1.5 V
40
60
40
60
40
60
40
60
%
8a*
BCLK Pulse Width High
Measured at 1.5 V
20
30
16
24
12
18
10
15
nS
8b*
BCLK Pulse Width Low
Measured at 1.5 V
20
30
16
24
12
18
10
15
nS
9
PCLK, BCLK Frequency Stability
—
1000
—
1000
—
1000
—
1000
ppm
10
PCLK to BCLK Skew
—9—9—
N/A
—
N/A
nS
Figure B-7. Clock Input Timing Diagram
1
4A
4B
2
3
7
6
VIH
VIL
VM
8B
8A
10
PCLK
BCLK
5
VIH
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Freescale Semiconductor, Inc.
For More Information On This Product,
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