17
IDT72255LA/72265LA CMOS SuperSync FIFO™
8,192 x 18 and 16,384 x 18
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
Figure 8. Read Cycle, Empty Flag and First Data Word Latency Timing (IDT Standard Mode)
NOTES:
1. tSKEW3 is the minimum time between a rising WCLK edge and a rising RCLK edge to guarantee that EF will go HIGH (after one RCLK cycle plus tREF). If the time between the
rising edge of WCLK and the rising edge of RCLK is less than tSKEW3, then EF deassertion may be delayed one extra RCLK cycle.
2. LD = HIGH.
3. First word latency: 60ns + tREF + 1*TRCLK.
NOTES:
1. tSKEW1 is the minimum time between a rising RCLK edge and a rising WCLK edge to guarantee that FF will go high (after one WCLK cycle pus tWFF). If the time between the
rising edge of the RCLK and the rising edge of the WCLK is less than tSKEW1, then the FF deassertion may be delayed one extra WCLK cycle.
2. LD = HIGH, OE = LOW, EF = HIGH
Figure 7. Write Cycle and Full Flag Timing (IDT Standard Mode)
D
0
- D
n
WEN
RCLK
FF
REN
t
ENH
t
ENH
Q
0
- Q
n
DATA READ NEXT DATA READDATA IN OUTPUT REGISTER
t
SKEW1
(1)
4670 drw10
WCLK
NO WRITE
1
2
1
2
t
DS
NO WRITE
t
WFF
t
WFF
t
WFF
t
A
t
ENS
t
ENS
t
SKEW1
(1)
t
DS
t
A
D
X
t
DH
t
CLK
t
CLKH
t
CLKL
D
X
+1
t
WFF
t
DH
NO OPERATION
RCLK
4670 drw 11
t
CLK
t
CLKH
t
CLKL
t
ENH
t
REF
t
A
t
OLZ
t
OE
Q
0
- Q
n
WCLK
(1)
t
SKEW3
D
0
- D
n
t
ENS
t
ENS
t
ENH
t
DS
t
DHS
D
0
1
2
t
OLZ
NO OPERATION
LAST WORD
D
0
D
1
D
1
t
ENS
t
ENH
t
DS
t
DH
t
OHZ
LAST WORD
t
REF
t
ENH
t
ENS
t
A
t
A
t
REF
t
ENS
t
ENH
