38
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T7285/72T7295/72T72105/72T72115 2.5V TeraSync
™™
™™
™ 72-BIT FIFO
16,384 x 72, 32,768 x 72, 65,536 x 72, 131,072 x 72
Figure 16. Read Cycle and Read Chip Select Timing (First Word Fall Through Mode)
WCLK
12
WEN
D0 - Dn
RCLK
REN
Q0 - Qn
PAF
HF
PAE
IR
OR
W
1
W
2
W
3
W
m+2
W
[m+3]
t
RCSHZ
t
SKEW1
t
ENH
t
DS
t
DH
t
A
t
A
t
PAFS
t
WFF
t
WFF
t
ENS
RCS
t
SKEW2
W
D
5994 drw21
t
PAES
W
[D-n]
W
[D-n-1]
t
A
t
A
W
[D-1]
W
D
t
A
W
[D-n+1]
W
[m+4]
W
[D-n+2]
(1)
(2)
t
ENS
1
t
ENS
t
RCSLZ
t
ENS
t
HF
t
REF
D-1
][
W
D-1
][
W
t
ENH
NOTES:
1. t
SKEW1 is the minimum time between a rising RCLK edge and a rising WCLK edge to guarantee that IR will go LOW after one WCLK cycle plus tWFF. If the time between the rising edge of RCLK and the rising edge of WCLK
is less than t
SKEW1, then the IR assertion may be delayed one extra WCLK cycle.
2. t
SKEW2 is the minimum time between a rising RCLK edge and a rising WCLK edge to guarantee that PAF will go HIGH after one WCLK cycle plus tPAFS. If the time between the rising edge of RCLK and the rising edge of WCLK
is less than t
SKEW2, then the PAF deassertion may be delayed one extra WCLK cycle.
3. LD = HIGH.
4. n = PAE Offset, m = PAF offset and D = maximum FIFO depth.
5. D = 16,385 for IDT72T7285, 32,769 for IDT72T7295, 65,537 for IDT72T72105 and 131,073 for IDT72T72115.
6. OE = LOW.
