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17
COMMERCIALANDINDUSTRIAL
TEMPERATURERANGES
IDT72275/72285
CMOS SuperSync FIFO 32,768 x 18 and 65,536 x 18
Figure
9.
Write
Timing
(First
Word
Fall
Through
Mode)
NOTES:
1.
tSKEW3
is
the
minimum
time
between
a
rising
WCLK
edge
and
a
rising
RCLK
edge
to
guarantee
that
OR
will
go
LOW
after
two
RCLK
cycles
plus
t
REF
.If
the
time
between
the
rising
edge
of
WCLK
and
the
rising
edge
of
RCLK
is
less
than
t
SKEW3
,then
OR
assertion
may
be
delayed
one
extra
RCLK
cycle.
2.
tSKEW2
is
the
minimum
time
between
a
rising
WCLK
edge
and
a
rising
RCLK
edge
to
guarantee
that
PAE
will
go
HIGH
after
one
RCLK
cycle
plus
t
PAE
.If
the
time
between
the
rising
edge
of
WCLK
and
the
rising
edge
of
RCLK
is
less
than
tS
KEW2
,then
the
PAE
deassertion
may
be
delayed
one
extra
RCLK
cycle.
3.
LD
=
HIGH,
OE
=
LOW
4.
n=
PAE
offset,
m
=
PAF
offset
and
D
=
maximum
FIFO
depth.
5.
D
=
32,769
for
IDT72275
and
65,537
for
IDT72285.
W
1
W
2
W
4
W
[n
+2]
W
[D-m-1]
W
[D-m-2]
W
[D-1]
W
D
W
[n+3]
W
[n+4]
W
[D-m]
W
[D-m+1]
WCLK
WEN
D
0
-
D
17
RCLK
tDH
tDS
tSKEW3
(1)
REN
Q
0
-Q
17
PAF
HF
PAE
IR
tDS
tSKEW2
tA
tREF
OR
tHF
tPAF
tWFF
W
[D-m+2]
W
1
tENH
4674
drw12
DATA
IN
OUTPUT
REGISTER
(2)
W
3
1
2
3
1
D-1
2
+1
]
[
W
D-1
+2
]
[
W
2
D-1
+3
]
[
W
2
1
2
tPAE
tENS