CY7C4421V/4201V/4211V/4221V
PRELIMINARY
CY7C4231V/4241V/4251V
Switching Waveforms (continued)
Programmable Almost Full Flag Timing
tCLKH
tCLKL
WCLK
WEN1
tENS tENH
Note 19
WEN2
(if applicable)
PAF
RCLK
REN1,
REN2
tENS tENH
FULL − M+1 WORDS
IN FIFO
Note 20
tPAF
FULL − M WORDS
IN FIFO [21]
tSKEW2 [22]
tENS
tENS tENH
tPAF
42X1V–13
Write Programmable Registers
tCLKH
tCLK
tCLKL
WCLK
WEN2/LD
tENS
tENH
WEN1
tENS
tDS
tDH
D0 –D8
PAE OFFSET
LSB
PAE OFFSET
MSB
PAF OFFSET
LSB
PAF OFFSET
MSB
42X1V–14
Notes:
19. If a write is performed on this rising edge of the write clock, there will be Full − (m−1) words of the FIFO when PAF goes LOW.
20. PAF offset = m.
21. 64-m words for CY7C4421V, 256-m words in FIFO for CY7C4201V, 512−m words for CY7C4211V, 1024−m words for CY7C4221V, 2048−m words for
CY7C4231V, 4096−m words for CY7C4241V, 8192-m words for CY7C4251V.
22. tSKEW2 is the minimum time between a rising RCLK edge and a rising WCLK edge for PAF to change during that clock cycle. If the time between the rising edge of RCLK
and the rising edge of WCLK is less than tSKEW2, then PAF may not change state until the next WCLK.
10