11 / 20 page
CY7C4255V/CY7C4265V
CY7C4275V/CY7C4285V
Document #: 38-06012 Rev. *A
Page 11 of 20
Notes:
21. PAE offset
− n.
22. tSKEW3 is the minimum time between a rising WCLK and a rising RCLK edge for PAE to change state during that clock cycle. If the time between the edge of WCLK and the
rising RCLK is less than tSKEW3, then PAE may not change state until the next RCLK.
23. If a read is performed on this rising edge of the read clock, there will be Empty + (n
−1) words in the FIFO when PAE goes LOW.
24. PAF offset = m. Number of data words written into FIFO already = 8192
− (m + 1) for the CY7C4255V, 16384 − (m + 1) for the CY7C4265V, 32768 − (m +
1) for the CY7C4275V, and 65536
− (m + 1) for the CY7C4285V.
25. PAF is offset = m.
26. 8192
− m words in CY7C4255V, 16384 − m words in CY7C4265V, 32768 − m words in CY7C4275V, and 65536 − m words in CY7C4285V.
27. 8192
− (m + 1) words in CY7C4255V, 16384 − (m + 1) words in CY7C4265V, 32768 − (m + 1) words in CY7C4275V, and 65536 − (m + 1) words in CY7C4285V.
Switching Waveforms (continued)
Note
tENH
Programmable Almost Empty Flag Timing (applies only in SMODE (SMODE is LOW))
WCLK
PAE
RCLK
tCLKH
tENS
tCLKL
tENS
tPAE synch
N+ 1 WORDS
IN FIFO
4275V–16
tENH
tENS
tPAE synch
REN
WEN
tSKEW3
Note
[22]
21
23
Note
tENH
Programmable Almost Full Flag Timing
WEN
WCLK
PAF
REN
RCLK
tCLKH
tPAF
tENS
tCLKL
tENS
tPAF
4275V–17
FULL– M WORDS
IN FIFO
FULL– (M+1) WORDS
IN FIFO [27]
[26]
24
[25]
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