IDT72P51759L6BBI8 IDT, Integrated Device Technology Inc, IDT72P51759L6BBI8 Datasheet - Page 31

• Manufacturer Part Number: IDT72P51759L6BBI8
• Description: IC FLOW CTRL 36BIT 256-BGA
• Manufacturer: IDT, Integrated Device Technology Inc

Specifications of IDT72P51759L6BBI8

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 72P51759L6BBI8

SWITCHING QUEUES ON THE READ PORT
can be configured up to a maximum of 128 queues. Data is read from a queue
using the Data Output (Qout) bus, Read Clock (RCLK) and Read Enable (REN)
signals. Selecting a queue on the read port occurs by placing the queue address
on the Read Address bus (RDADD) during a rising edge of RCLK while Read
supports changing (switching) queues every four (4) clock cycles. To switch
from the Present Queue (PQ) to another queue requires a queue address to
be placed on the Read Address Bus (RDADD) bus and a rising edge of Read
Clock (RCLK) and Read Address Enable (RADEN) is HIGH. There are no
restrictions as to the order to which queues are selected or switched into or out
of.
NOTE:
PQ = Present Queue
NQ = Next Queue
IDT72P51749/72P51759/72P51769 1.8V, MULTI-QUEUE FLOW-CONTROL DEVICES
(128 QUEUES) 36 BIT WIDE CONFIGURATION 1,179,648, 2,359,296, and 4,718,592
bits
The IDT72P51749/72P51759/72P51769 multi-queue flow-control devices
The IDT72P51749/72P51759/72P51769 multi-queue flow-control device
RADEN
RCLK
Qout
REN
RDADD
RADEN
RCLK
PQ
Queue
address
Figure 10. Read Port Switching Queues Signal Sequence
PQ
QS-1
Queue Switch Cycles
Figure 11. Switching Queues Bus Efficiency
Queue Switch Cycle
QS0
PQ
QS1
PQ
31
Address Enable (RADEN) is HIGH. For reference, the state of Read Enable
(REN) is a “Don’t Care” during a read port queue selection. REN has
significance during the queue mark operation. Selecting a queue requires 4
WCLK cycles. Refer to Figure 10, Read Port Switching Queues Signal
Sequence.
the IDT72P51749/72P51759/72P51769 multi-queue flow-control device can
continue to read from the Present Queue (PQ). The Present Queue is defined
as the current selected queue. Refer to Figure 11. Switching Queues Bus
Efficiency.
For maximum efficiency, during the 4 clock cycles required to switch queues
QS2
PQ
Queue
address
QS3
NQ
NQ
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
FEBRUARY 10, 2009
6714 drw16
6714 drw17