48
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T2098/108/118/128 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 20-BIT/10-BIT CONFIGURATIONS
32K x 20/64K x 10, 64K x 20/128K x 10, 128K x 20/256K x 10, 256K x 20/512K x 10
FEBRUARY 13, 2009
NOTES:
1. m = PAF offset.
2. D = maximum FIFO Depth.
In IDT Standard mode: if x20 Input or x20 Output bus Width is selected, D = 32,768 for the IDT72T2098, 65,536 for the IDT72T20108, 131,072 for the IDT72T20118, 262,144 for
the IDT72T20128. If both x10 Input and x10 Output bus Widths are selected, D = 65,536 for the IDT72T2098, 131,072 for the IDT72T20108, 262,144 for the IDT72T20118, 524,288
for the IDT72T20128.
In FWFT mode: if x20 Input or x20 Output bus Width is selected, D = 32,769 for the IDT72T2098, 65,537 for the IDT72T20108, 131,073 for the IDT72T20118, 262,145 for the IDT72T20128.
If both x10 Input and x10 Output bus Widths are selected, D = 65,537 for the IDT72T2098, 131,073 for the IDT72T20108, 262,145 for the IDT72T20118, 524,289 for the IDT72T20128.
3. PAF is asserted and updated on the rising edge of WCLK only.
4. tSKEW3 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 tSKEW3, then the PAF deassertion time may be delayed one extra WCLK cycle.
5. RCS = LOW.
Figure 29. Programmable Almost-Full Flag Timing (IDT Standard and FWFT Modes)
NOTES:
1. n = PAE offset.
2. For IDT Standard Mode.
3. For FWFT Mode.
4. PAE is asserted and updated on the rising edge of RCLK only.
5.
tSKEW3 is the minimum time between a rising WCLK edge and a rising RCLK edge to guarantee that PAE will go HIGH (after one RCLK cycle plus tPAES). If the time between the
rising edge of WCLK and the rising edge of RCLK is less than tSKEW3, then the PAE deassertion may be delayed one extra RCLK cycle.
6. RCS = LOW.
Figure 30. Programmable Almost-Empty Flag Timing (IDT Standard and FWFT Modes)
WCLK
WEN
PAF
RCLK
REN
5996 drw32
1
2
12
D-(m+1) words
in FIFO
(2)
D - m words in FIFO
(2)
D - (m +1) words in FIFO
(2)
t
ENH
t
ENS
t
PAFS
t
ENS
t
ENH
t
CLKL1
t
SKEW3
(3)
t
PAFS
t
CLKL1
WCLK
WEN
PAE
RCLK
12 12
REN
5996 drw33
n + 1 words in FIFO
(2)
,
n + 2 words in FIFO
(3)
t
ENS
t
SKEW3
(4)
t
ENH
t
PAES
n words in FIFO
(2)
,
n + 1 words in FIFO
(3)
t
PAES
n words in FIFO
(2)
,
n + 1 words in FIFO
(3)
t
ENS
t
ENH
t
CLKH1
t
CLKL1
