CY7C4801/4811/4821
CY7C4831/4841/4851
Switching Waveforms
(continued)
Programmable Almost Empty Flag Timing
t
CLKH
WCLKA,WCLKB
t
ENS
t
ENH
WENA1(WENB1)
t
CLKL
WENA2(WENB2)
(if applicable)
t
ENS
t
ENH
PAEA(PAEB)
t
SKEW2
RCLKA(RCLKB)
t
ENS
t
ENH
RENA1, RENA2
(RENB1,RENB2)
48X1–12
Note
18
t
PAE
[17]
N + 1 WORDS
IN FIFO
Note
19
t
PAE
Programmable Almost Full Flag Timing
t
CLKH
WCLKA,WCLKB
t
ENS
t
ENH
WENA1(WENB1)
Note
21
t
ENS
t
ENH
PAFA(PAFB)
FULL
−
M+1 WORDS
IN FIFO
t
PAF
FULL
−
M WORDS
IN FIFO
[22]
t
SKEW2
RCLKA(RCLKB)
t
ENS
RENA1, RENA2
(RENB1,RENB2)
48X1–13
t
CLKL
Note
20
WENA2(WENB2)
(if applicable)
[23]
t
PAF
t
ENS
t
ENH
Notes:
17. t
SKEW2
is the minimum time between a rising (WCLKA,WCLKB) and a rising (RCLKA,RCLKB) edge for (PAEA,PAEB) to change state during that clock cycle. If the time
between the edge of (WCLKA,WCLKB) and the rising (RCLKA,RCLKB) is less than t
SKEW2
, then (PAEA,PAEB) may not change state until the next RCLK.
18. (PAEA,PAEB) offset = n.
19. If a read is preformed on this rising edge of the read clock, there will be Empty + (n-1) words in the FIFO when (PAEA,PAEB) goes LOW.
20. If a write is performed on this rising edge of the write clock, there will be Full - (m-1) words of the FIFO when (PAFA,PAFB) goes LOW.
21. (PAFA,PAFB) offset = m.
22. 256-m words in FIFO for CY7C4801, 512-m words for CY7C4811, 1024-m words for CY7C4821, 2048-m words for CY7C4831, 4096-m words for CY7C4841,
8192-m words for CY7C4851.
23. t
SKEW2
is the minimum time between a rising (RCLKA,RCLKB) edge and a rising (WCLKA,WCLKB) edge for (PAFA,PAFB) to change during that clock cycle. If the time
between the rising edge of (RCLKA,RCLKB) and the rising edge of (WCLKA,WCLKB) is less than t
SKEW2
, then (PAFA,PAFB) may not change state until the next
(WCLKA,WCLKB).
Document #: 38-06005 Rev. **
Page 12 of 23
CYPRESS [ CYPRESS SEMICONDUCTOR ]
