36
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72V51433/72V51443/72V51453 3.3V, MULTI-QUEUE FLOW-CONTROL DEVICES
(16 QUEUES) 18 BIT WIDE CONFIGURATION 589,824, 1,179,648 and 2,359,296 bits
Figure 14. Read Queue Selection with Reads Disabled
Figure 15. Read Queue Select, Read Operation and
OE
Timing
RCLK
5939 drw16
t
AH
t
AS
Q
n
RDADD
t
QH
t
QS
RADEN
REN
t
ENS
t
AH
t
AS
Q
P
t
QH
t
QS
Q
OUT
Q
P
W
D
t
A
Q
P
W
D+1
t
A
t
A
Q
P
W
D+2
t
A
Q
n
W
X+1
OV
t
ENS
t
ENH
t
A
Q
P
W
D+3
Q
P
W
D+4
*A* *B* *C* *D* *E* *F* *G* *H* *I* *J*
t
A
t
ENH
Q
n
W
X
RCLK
RADEN
t
QH
t
QS
t
AH
t
AS
RDADD
Q
A
OV
5939 drw17
Qout
t
ROV
t
OLZ
t
A
Q
A
W
0
PFT
t
A
t
A
t
ENS
REN
t
AH
t
AS
Q
B
t
QH
t
QS
OE
t
OE
t
A
Previous Data in O/P Register
t
A
Q
A
W
1
No Read
Q
B is Empty
t
ROV
*B* *C* *E* *F**D**A* *H* *I**G*
t
ENH
t
ENS
Q
A
W
2
Q
A
W
3
Q
A
W
4
t
OHZ
Cycle:
*A* Word Wd+1 is read from the previously selected queue, Qp.
*B* Reads are disabled, word Wd+1 remains on the output bus.
*C* A new queue, Qn is selected for read port operations.
*D* Due to FWFT operation Word, Wd+2 of Qp is read out regardless of REN.
*E* The next available word Wx of Qn is read out regardless of REN, 2 RCLK cycles after queue selection. This is FWFT operation.
*F* The queue, Qp is again selected.
*G* Word Wx+1 is read from Qn regardless of REN, this is due to FWFT.
*H* Word Wd+3 is read from Qp, this read occurs regardless of REN due to FWFT operation.
*I* Word Wd+4 is read from Qp.
*J* Reads are disabled on this cycle, therefore no further reads occur.
NOTES:
1. The Output Valid flag, OV is HIGH therefore the previously selected queue has been read to empty. The Output Enable input is Asynchronous, therefore the Qout output bus
will go to Low-Impedance after time t
OLZ.
The data currently on the output register will be available on the output after time t
OE. This data is the previous data on the output register, this is the last word read out of the
previous queue.
2. In expansion mode the OE inputs of all devices should be connected together. This allows the output busses of all devices to be High-Impedance controlled.
Cycle:
*A* Queue A is selected for reads. No data will fall through on this cycle, the previous queue was read to empty.
*B* No data will fall through on this cycle, the previous queue was read to empty.
*C* Word, W0 from Qa is read out regardless of REN due to FWFT operation. The OV flag goes LOW indicating that Word W0 is valid.
*D* Reads are disabled therefore word, W0 of Qa remains on the output bus.
*E* Reads are again enabled so word W1 is read from Qa.
*F* Word W2 is read from Qa.
*G* Queue, Qb is selected on the read port. This queue is actually empty. Word, W3 is read from Qa.
*H* Word, W4 falls through from Qa.
*I* Output Valid flag, OV goes HIGH to indicate that Qb is empty. Data on the output port is no longer valid.
Output Enable is taken HIGH, this is Asynchronous so the output bus goes to High-Impedance after time, t
OHZ.
