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8251A/S2657
A.C.
CHARACTERISTICS
Bus Parameters
!(Note
1)
Read
Cycle:
SYMBOL
PARAMETER
tAR
Address
Stable
Before
READ
(CS, C/O)
tRA
Address
Hold
Time
for
READ
(CS,
C/O)
tRR
READ Pulse Width
tRD
Data Delay
from
READ
tDF
READ
to
Data
Floating
Write Cycle:
SYMBOL
PARAMETER
tAW
Address
Stable
Before
WR
ITE
tWA
Address
Hold
Time
for
WR
ITE
tww
WRITE
Pulse
Width
tow
Data
Set
Up
Time
for
WRITE
two
Data Hold
Time
for
WRITE
tRV
Recovery
Time
Between
WRITES
MIN.
50
50
250
10
MIN.
50
50
250
150
50
6
MAX.
250
100
MAX.
NOTES:
1.
AC
timings measured
VOH
= 2.0,
VOL
= 0.8, and with load circuit of Figure
1.
2. Chip Select
(CS)
and Command/Oata
(C/O)
are considered
as
Addresses.
3. Assumes that Address
is
valid
before
RD"
UNIT
ns
ns
ns
ns
ns
UNIT
ns
ns
ns
ns
ns
tCY
4.
This recovery time
is
for
Mode
InitialiZ!'tion only. Write Data
is
allowed only when TxRDY =
1.
TEST
CONDITIONS
Note
2
Note
2
3,
CL
=
150
pF
TEST
CONDITIONS
Note
4
Recovery Time between Writas for Asynchronous
Mode
is
8 tCY and for Synchronous
Mode
is
16 tCY'
Input Waveforms for
AC
Tests
2.4----
X
_
___
oJ
~::
0.45
TEST
POINTS
9-4
:::x'-
___
_
00216A