IDT72T7285/72T7295/72T72105/72T72115 2.5V TeraSync
16,384 x 72, 32,768 x 72, 65,536 x 72, 131,072 x 72
72-BIT FIFO
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
WCLK
tENS
tENH
WEN
tDS
t
DH
tDS
t
DH
tDS
tDH
Wn+1
Wn+2
Wn+3
D0 - Dn
tSKEW1
1
2
RCLK
b
e
h
a
d
g
c
i
f
tERCLK
ERCLK
tENS
tENH
REN
RCS
tENS
tCLKEN
tCLKEN
tCLKEN
tCLKEN
EREN
Qn
tA
tA
t
RCSLZ
HIGH-Z
Wn+1
Wn+2
Wn+3
tREF
tREF
OR
tA
tA
tA
O/P
Reg.
Wn
Last Word
Wn+1
Wn+2
Wn+3
5994 drw34
NOTE:
1. The O/P Register is the internal output register. Its contents are available on the Qn output bus only when RCS and OE are both active, LOW, that is the bus is not in High-
Impedance state.
2. OE is LOW.
Cycle:
a&b. At this point the FIFO is empty, OR is HIGH.
RCS and REN are both disabled, the output bus is High-Impedance.
c.
Word Wn+1 falls through to the output register, OR goes active, LOW.
RCS is HIGH, therefore the Qn outputs are High-Impedance. EREN goes LOW to indicate that a new word has been placed on the output register.
EREN goes HIGH, no new word has been placed on the output register on this cycle.
No Operation.
RCS is LOW on this cycle, therefore the Qn outputs go to Low-Impedance and the contents of the output register (Wn+1) are made available.
NOTE: In FWFT mode is important to take RCS active LOW at least one cycle ahead of REN, this ensures the word (Wn+1) currently in the output register is made
available for at least one cycle.
d.
e.
f.
g.
h.
i.
REN goes active LOW, this reads out the second word, Wn+2.
EREN goes active LOW to indicate a new word has been placed into the output register.
Word Wn+3 is read out, EREN remains active, LOW indicating a new word has been read out.
NOTE: Wn+3 is the last word in the FIFO.
This is the next enabled read after the last word, Wn+3 has been read out. OR flag goes HIGH and EREN goes HIGH to indicate that there is no new word available.
Figure 29. Echo RCLK and Echo REN Operation (FWFT Mode Only)
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IDT [ INTEGRATED DEVICE TECHNOLOGY ]
