MOTOROLA
A-22
ELECTRICAL CHARACTERISTICS
MC68331
USER’S MANUAL
A
Notes for Tables A–8 and A–8a:
1. All AC timing is shown with respect to 20% V
DD
and 70% V
DD
levels unless otherwise noted.
2. When the previous bus cycle is not an ECLK cycle, the address may be valid before ECLK goes low.
3. Address access time = t
Ecyc
– t
EAD
– t
EDSR
.
4. Chip select access time = t
Ecyc
– t
ECSD
– t
EDSR
.
Table A-8 16.78 MHz ECLK Bus Timing
(V
DD
= 5.0 Vdc
±
10%, V
SS
= 0 Vdc, T
A
= T
L
to T
H
)
Num
Characteristic
Symbol
Min
Max
Unit
E1
ECLK Low to Address Valid
2
t
EAD
t
EAH
t
ECSD
t
ECSH
t
ECSN
t
EDSR
t
EDHR
t
EDHZ
t
ECDH
t
ECDZ
t
EDDW
t
EDHW
t
EACC
t
EACS
t
EAS
—
60
ns
E2
ECLK Low to Address Hold
15
—
ns
E3
ECLK Low to CS Valid (CS delay)
—
150
ns
E4
ECLK Low to CS Hold
15
—
ns
E5
CS Negated Width
30
—
ns
E6
Read Data Setup Time
30
—
ns
E7
Read Data Hold Time
5
—
ns
E8
ECLK Low to Data High Impedance
—
60
ns
E9
CS Negated to Data Hold (Read)
0
—
ns
E10
CS Negated to Data High Impedance
—
1
t
cyc
t
cyc
ns
E11
ECLK Low to Data Valid (Write)
—
2
E12
ECLK Low to Data Hold (Write)
Address Access Time (Read)
3
Chip Select Access Time (Read)
4
15
—
E13
386
—
ns
E14
296
—
ns
E15
Address Setup Time
1/2
—
t
cyc
Table A-8a 20.97 MHz ECLK Bus Timing
(V
DD
= 5.0 Vdc
±
5%, V
SS
= 0 Vdc, T
A
= T
L
to T
H
)
Num
E1
E2
E3
E4
E5
E6
E7
E8
E9
E10
E11
E12
E13
E14
E15
Characteristic
Symbol
t
EAD
t
EAH
t
ECSD
t
ECSH
t
ECSN
t
EDSR
t
EDHR
t
EDHZ
t
ECDH
t
ECDZ
t
EDDW
t
EDHW
t
EACC
t
EACS
t
EAS
Min
—
10
—
10
25
25
5
—
0
—
—
10
308
236
1/2
Max
48
—
120
—
—
—
—
48
—
1
2
—
—
—
—
Unit
ns
ns
ns
ns
ns
ns
ns
ns
ns
t
cyc
t
cyc
ns
ns
ns
t
cyc
ECLK Low to Address Valid
2
ECLK Low to Address Hold
ECLK Low to CS Valid (CS delay)
ECLK Low to CS Hold
CS Negated Width
Read Data Setup Time
Read Data Hold Time
ECLK Low to Data High Impedance
CS Negated to Data Hold (Read)
CS Negated to Data High Impedance
ECLK Low to Data Valid (Write)
ECLK Low to Data Hold (Write)
Address Access Time (Read)
3
Chip Select Access Time (Read)
4
Address Setup Time