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IDT72V51233/72V51243/72V51253 3.3V, MULTI-QUEUE FLOW-CONTROL DEVICES
(4 QUEUES) 18 BIT WIDE CONFIGURATION 589,824, 1,179,648 and 2,359,296 bits
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
Figure 9. Write Queue Select, Write Operation and Full Flag Operation
WCLK
WADEN
t
QH
t
QS
t
AH
t
AS
WRADD
Q
x
FF
t
WFF
5941 drw12
WEN
t
ENS
t
AH
t
AS
Q
y
t
QH
t
QS
t
DH
t
DS
Q
X
W
D
t
DH
Q
y
W
D-2
W
D-1
Q
y
t
DH
Din
t
WFF
t
WFF
Previous Q Status
No Writes
Queue Full
*A* *B* *C* *D* *E* *F* *G*
t
DS
Q
y
W
D
t
DS
t
DH
t
ENH
t
WFF
t
WFF
RCLK
t
SKEW1
t
QS
t
QH
REN
t
ENS
RDADD
Q
y
RADEN
Qout
t
A
Previous Q, Word, W Previous Q, W
+1
PFT
t
A
Qy, W
0
PFT
t
A
t
A
Qy, W
1
Qy, W
2
*H* *I* *J*
t
AS
t
AH
*AA* *BB* *CC* *DD
*
*EE* *FF*
t
DS
NOTE:
OE is active LOW.
Cycle:
*A* Queue, Qx is selected on the write port.
The FF flag is providing status of a previously selected queue, within the same device.
*AA* Queue, Qy is selected for read operations.
*B* The FF flag output updates to show the status of Qx, it is not full.
*BB* Word W+1 is read from the previous queue regardless of REN due to FWFT.
*C* Word, Wd is written into Qx. This causes Qx to go full.
*CC* Word, W0 is read from Qy regardless of REN, this is due to the FWFT effect.
*D* Queue, Qy is selected within the same device as Qx. A write to Qx cannot occur on this cycle because it is full, FF is LOW.
*DD* No reads occur, REN is HIGH.
*E* Again, a write to Qx cannot occur on this cycle because it is full, FF is LOW. The FF flag updates after time t
WFF to show that queue, Qy is not full.
*EE* Word, W1 is read from Qy, this causes Qy to go “not full”, FF flag goes HIGH after time, t
SKEW1 + tWFF. Note, if tSKEW1 is violated the time FF HIGH will be: tSKEW1 + WCLK + tWFF.
*F* Word, Wd-2 is written into Qy.
*FF* Word, W2 is read from Qy.
*G* Word, Wd-1 is written into Qy.
*H* Word, Wd is written into Qy, this causes Qy to go full, FF goes LOW.
*I* No writes occur to Qy.
*J* Qy goes “not full” based on reading word W1 from Qy on cycle *EE*.
