IDT72T51333 Datasheet, PDF (27/55 Pages) Integrated Device Technology – 2.5V MULTI-QUEUE FLOW-CONTROL DEVICES (4 QUEUES) 36 BIT WIDE CONFIGURATION 589,824 bits, 1,179,648 bits and 2,359,296 bits

IDT72T51333/72T51343/72T51353 2.5V, MULTI-QUEUE FLOW-CONTROL DEVICES
(8 QUEUES) 18 BIT WIDE CONFIGURATION 589,824, 1,179,648 and 2,359,296 bits
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
ECHO READ CLOCK (ERCLK)
The Echo Read Clock output is provided in both HSTL and LVTTL mode,
selectable via IOSEL. The ERCLK is a free-running clock output, it will always
follow the RCLK input regardless of REN and RADEN.
The ERCLK output follows the RCLK input with an associated delay. This
delay provides the user with a more effective read clock source when reading
data from the Qn outputs. This is especially helpful at high speeds when variables
within the device may cause changes in the data access times. These variations
in access time maybe caused by ambient temperature, supply voltage, device
characteristics. The ERCLK output also compensates for any trace length
delays between the Qn data outputs and receiving devices inputs.
Any variations effecting the data access time will also have a corresponding
effect on the ERCLK output produced by the queue device, therefore the ERCLK
output level transitions should always be at the same position in time relative to
the data outputs. Note, that ERCLK is guaranteed by design to be slower than
the slowest Qn, data output. Refer to Figure 3, Echo Read Clock and Data
Output Relationship and Figure 23, Echo RCLK & Echo REN Operation for
timing information.
ECHO READ ENABLE (EREN)
The Echo Read Enable output is provided in both HSTL and LVTTL mode,
selectable via IOSEL.
The EREN output is provided to be used in conjunction with the ERCLK
output and provides the reading device with a more effective scheme for reading
data from the Qn output port at high speeds. The EREN output is controlled by
internal logic that behaves as follows: The EREN output is active LOW for the
RCLK cycle that a new word is read out of the queue. That is, a rising edge of
RCLK will cause EREN to go active (LOW) if REN is active and the queue is
NOT empty.
RCLK
ERCLK
tERCLK
tERCLK
QSLOWEST⁽³⁾
tA
tD
6113 drw07
NOTES:
1. REN is LOW. OE is LOW.
2. tERCLK > tA, guaranteed by design.
3. Qslowest is the data output with the slowest access time, tA.
4. Time, tD is greater than zero, guaranteed by design.
Figure 3. Echo Read Clock and Data Output Relationship
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