IDT72V3622L10PFG 데이터 시트보기 (PDF) - Integrated Device Technology
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IDT72V3622L10PFG
Integrated Device Technology
IDT72V3622L10PFG Datasheet PDF : 29 Pages
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IDT72V3622/72V3632/72V3642 CMOS 3.3V SyncBiFIFOTM
256 x 36 x 2, 512 x 36 x 2, 1,024 x 36 x 2
new data is present in the FIFO output register. When the Output Ready flag
is LOW, the previous data word is present in the FIFO output register and
attempted FIFO reads are ignored.
In the IDT Standard mode, the Empty Flag (EFA, EFB) function is
selected. When the Empty Flag is HIGH, data is available in the FIFO’s RAM
for reading to the output register. When the Empty Flag is LOW, the previous
data word is present in the FIFO output register and attempted FIFO reads are
ignored.
The Empty/Output Ready flag of a FIFO is synchronized to the port clock
that reads data from its array. For both the FWFT and IDT Standard modes,
the FIFO read pointer is incremented each time a new word is clocked to its
output register. The state machine that controls an Output Ready flag monitors
a write pointer and read pointer comparator that indicates when the FIFO
memory status is empty, empty+1, or empty+2.
In FWFT mode, from the time a word is written to a FIFO, it can be shifted
to the FIFO output register in a minimum of three cycles of the Output Ready
flag synchronizing clock. Therefore, an Output Ready flag is LOW if a word in
memory is the next data to be sent to the FlFO output register and three cycles
of the port Clock that reads data from the FIFO have not elapsed since the time
the word was written. The Output Ready flag of the FIFO remains LOW until
the third LOW-to-HIGH transition of the synchronizing clock occurs, simulta-
neously forcing the Output Ready flag HIGH and shifting the word to the FIFO
output register.
COMMERCIAL TEMPERATURE RANGE
In IDT Standard mode, from the time a word is written to a FIFO, the Empty
Flag will indicate the presence of data available for reading in a minimum of two
cycles of the Empty Flag synchronizing clock. Therefore, an Empty Flag is LOW
if a word in memory is the next data to be sent to the FlFO output register and
two cycles of the port Clock that reads data from the FIFO have not elapsed
since the time the word was written. The Empty Flag of the FIFO remains LOW
until the second LOW-to-HIGH transition of the synchronizing clock occurs,
forcing the Empty Flag HIGH; only then can data be read.
A LOW-to-HIGH transition on an Empty/Output Ready flag synchronizing
clock begins the first synchronization cycle of a write if the clock transition occurs
at time tSKEW1 or greater after the write. Otherwise, the subsequent clock cycle
can be the first synchronization cycle (see Figures 8 through 11 for EFA/ORA
and EFB/ORB timing diagrams).
FULL/INPUT READY FLAGS (FFA/IRA, FFB/IRB)
This is a dual purpose flag. In FWFT mode, the Input Ready (IRA and IRB)
function is selected. In IDT Standard mode, the Full Flag (FFA and FFB)
function is selected. For both timing modes, when the Full/Input Ready flag is
HIGH, a memory location is free in the FIFO to receive new data. No memory
locations are free when the Full/Input Ready flag is LOW and attempted writes
to the FIFO are ignored.
TABLE 4 — FIFO1 FLAG OPERATION (IDT STANDARD AND FWFT MODES)
Synchronized
Synchronized
Number of Words in FIFO(1,2)
to CLKB
to CLKA
IDT72V3622(3)
IDT72V3632(3)
IDT72V3642(3)
EFB/ORB
AEB
AFA
FFA/IRA
0
0
0
L
L
H
H
1 to X1
1 to X1
1 to X1
H
L
H
H
(X1+1) to [256-(Y1+1)]
(X1+1) to [512-(Y1+1)]
(X1+1) to [1,024-(Y1+1)]
H
H
H
H
(256-Y1) to 255
(512-Y1) to 511
(1,024-Y1) to 1,023
H
H
L
H
256
512
1,024
H
H
L
L
NOTES:
1. When a word loaded to an empty FIFO is shifted to the output register, its previous FIFO memory location is free.
2. Data in the output register does not count as a "word in FIFO memory". Since in FWFT mode, the first word written to an empty FIFO goes unrequested to the output register (no
read operation necessary), it is not included in the FIFO memory count.
3. X1 is the Almost-Empty offset for FIFO1 used by AEB. Y1 is the Almost-Full offset for FIFO1 used by AFA. Both X1 and Y1 are selected during a reset of FIFO1 or programmed from
port A.
4. The ORB and IRA functions are active during FWFT mode; the EFB and FFA functions are active in IDT Standard mode.
TABLE 5 — FIFO2 FLAG OPERATION (IDT STANDARD AND FWFT MODES)
Synchronized
Synchronized
Number of Words in FIFO(1,2)
to CLKA
to CLKB
IDT72V3622(3)
IDT72V3632(3)
IDT72V3642(3)
EFA/ORA
AEA
AFB
FFB/IRB
0
0
0
L
L
H
H
1 to X2
1 to X2
1 to X2
H
L
H
H
(X2+1) to [256-(Y2+1)]
(X2+1) to [512-(Y2+1)]
(X2+1) to [1,024-(Y2+1)]
H
H
H
H
(256-Y2) to 255
(512-Y2) to 511
(1,024-Y2) to 1,023
H
H
L
H
256
512
1,024
H
H
L
L
NOTES:
1. When a word loaded to an empty FIFO is shifted to the output register, its previous FIFO memory location is free.
2. Data in the output register does not count as a "word in FIFO memory". Since in FWFT mode, the first word written to an empty FIFO goes unrequested to the output register (no
read operation necessary), it is not included in the FIFO memory count.
3. X2 is the Almost-Empty offset for FIFO2 used by AEA. Y2 is the Almost-Full offset for FIFO2 used by AFB. Both X2 and Y2 are selected during a reset of FIFO2 or programmed from
port A.
4. The ORA and IRB functions are active during FWFT mode; the EFA and FFB functions are active in IDT Standard mode.
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