Intel MCS48 User Manual page 296

8251
A.C.
CHARACTERISTICS
T
A
= 0°C
to
70°C;
V
cc
=
5.0V ±5%;
GND
= 0V
Bus
Parameters
(Note
1
Read
Cycle:
SYMBOL
PARAMETER
MIN.
MAX. UNIT TEST CONDITIONS
*AR
Address
Stable
Before R
EAD
(CS,
C/D) 50
ns
Note 2
50 ns
tRA Address Hold
Time
for
READ
(CS,
C/D)
Note 2
tRR
READ
Pulse
Width
250
ns
tRD Data Delay
from
READ
250
ns
3,
C
L
=
150 pF
tDF
READ
to Data Floating 10
100 ns
Write
Cycle:
SYMBOL PARAMETER
MIN.
MAX. UNIT TEST CONDITIONS
*AW
Address
Stable Before
WRITE
50
ns
*WA
Address Hold
Time
for
WRITE
50
ns
*ww
WRITE
Pulse
Width 250
ns
*DW Data
Set
Up Time
for
WRITE
150
ns
*WD
Data Hold Time
for
WRITE
30
ns
tRV Recovery Time Between
WRITES
6
tCY
Note 4
NOTES:
1.
AC
timings measured VrjH
=
2.0,
Vol
=
0.8,
and
with load
circuit
of Figure
1.
2.
Chip
Select (CS)
and Command/Data
(C/D)
are
considered
as Addresses.
3.
Assumes
that Address
is
valid
before
Rd*.
4.
This recovery time
is
for
Mode
Initialization
only. Write Data
is
allowed only
when
TxRDY
=
1.
Recovery
Time
between
Writes for
Asynchronous
Mode
is
8
tcY
ar|
d f°
r
Synchronous
Mode
is
16 tgY-
Input
Waveforms
for
AC
Tests
2.4
0.45
Xp,
TEST
POINTS
8-6
00216A