72V285L15TFI Integrated Device Technology (Idt), 72V285L15TFI Datasheet - Page 11

• Manufacturer Part Number: 72V285L15TFI
• Description: FIFO Mem Sync Dual Depth/Width Uni-Dir 64K x 18 64-Pin STQFP Tray
• Manufacturer: Integrated Device Technology (Idt)

Specifications of 72V285L15TFI

• Package: 64STQFP
• Configuration: Dual
• Bus Directional: Uni-Directional
• Density: 1.125 Mb
• Organization: 64Kx18
• Data Bus Width: 18 Bit
• Timing Type: Synchronous
• Expansion Type: Depth|Width
• Typical Operating Supply Voltage: 3.3 V
• Operating Temperature: -40 to 85 °C

SIGNAL DESCRIPTION
INPUTS:
DATA IN (D
CONTROLS:
MASTER RESET (MRS
a LOW state. This operation sets the internal read and write pointers to the
first location of the RAM array. PAE will go LOW, PAF will go HIGH, and
HF will go HIGH.
along with EF and FF are selected. EF will go LOW and FF will go HIGH.
If FWFT is HIGH, then the First Word Fall Through mode (FWFT), along with
IR and OR, are selected. OR will go HIGH and IR will go LOW.
127 words from the empty boundary and PAF is assigned a threshold 127
words from the full boundary; 127 words corresponds to an offset value of
07FH. Following Master Reset, parallel loading of the offsets is permitted,
but not serial loading.
1,023 words from the empty boundary and PAF is assigned a threshold
1,023 words from the full boundary; 1,023 words corresponds to an offset
value of 3FFH. Following Master Reset, serial loading of the offsets is
permitted, but not parallel loading.
describing the LD pin for further details.)
Master Reset is required after power up, before a write operation can take
place. MRS is asynchronous.
PARTIAL RESET (PRS
state. As in the case of the Master Reset, the internal read and write pointers are
set to the first location of the RAM array, PAE goes LOW, PAF goes HIGH, and
HF goes HIGH.
or First Word Fall Through, that mode will remain selected. If the IDT Standard
mode is active, then FF will go HIGH and EF will go LOW. If the First Word
Fall Through mode is active, then OR will go HIGH, and IR will go LOW.
unchanged. The programming method (parallel or serial) currently active
at the time of Partial Reset is also retained. The output register is initialized
to all zeroes. PRS is asynchronous.
operation, when reprogramming partial flag offset settings may not be
convenient.
RETRANSMIT (RT
accessed again. There are two stages: first, a setup procedure that resets the
read pointer to the first location of memory, then the actual retransmit, which
consists of reading out the memory contents, starting at the beginning of the
memory.
IDT72V275/72V285 3.3V CMOS SUPERSYNC FIFO
32,768 x 18 and 65,536 x 18
Data inputs for 18-bit wide data.
A Master Reset is accomplished whenever the MRS input is taken to
If LD is LOW during Master Reset, then PAE is assigned a threshold
Parallel reading of the registers is always permitted. (See section
During a Master Reset, the output register is initialized to all zeroes. A
See Figure 5, Master Reset Timing, for the relevant timing diagram.
A Partial Reset is accomplished whenever the PRS input is taken to a LOW
Whichever mode is active at the time of Partial Reset, IDT Standard mode
Following Partial Reset, all values held in the offset registers remain
A Partial Reset is useful for resetting the device during the course of
See Figure 6, Partial Reset Timing, for the relevant timing diagram.
The Retransmit operation allows data that has already been read to be
If LD is HIGH during Master Reset, then PAE is assigned a threshold
If FWFT is LOW during Master Reset then the IDT Standard mode,
0
- D
RT
RT
RT
RT)
17
)
MRS
MRS
MRS
MRS)
PRS
PRS
PRS)
PRS
TM
11
REN and WEN must be HIGH before bringing RT LOW.
the Retransmit setup by setting EF LOW. The change in level will only be
noticeable if EF was HIGH before setup. During this period, the internal
read pointer is initialized to the first location of the RAM array.
tions may begin starting with the first location in memory. Since IDT
Standard mode is selected, every word read including the first word
following Retransmit setup requires a LOW on REN to enable the rising
edge of RCLK. See Figure 11, Retransmit Timing (IDT Standard Mode), for
the relevant timing diagram.
setup by setting OR HIGH. During this period, the internal read pointer is set to
the first location of the RAM array.
the contents of the first location appear on the outputs. Since FWFT mode
is selected, the first word appears on the outputs, no LOW on REN is
necessary. Reading all subsequent words requires a LOW on REN to
enable the rising edge of RCLK. See Figure 12, Retransmit Timing (FWFT
Mode), for the relevant timing diagram.
FIRST WORD FALL THROUGH/SERIAL IN (FWFT/SI)
input determines whether the device will operate in IDT Standard mode or First
Word Fall Through (FWFT) mode.
mode will be selected. This mode uses the Empty Flag (EF) to indicate
whether or not there are any words present in the FIFO memory. It also uses
the Full Flag function (FF) to indicate whether or not the FIFO memory has
any free space for writing. In IDT Standard mode, every word read from the
FIFO, including the first, must be requested using the Read Enable (REN)
and RCLK.
be selected. This mode uses Output Ready (OR) to indicate whether or not
there is valid data at the data outputs (Q
to indicate whether or not the FIFO memory has any free space for writing.
In the FWFT mode, the first word written to an empty FIFO goes directly to
Q
quent words must be accessed using the Read Enable (REN) and RCLK.
PAF offsets into the programmable registers. The serial input function can
only be used when the serial loading method has been selected during
Master Reset. Serial programming using the FWFT/SI pin functions the
same way in both IDT Standard and FWFT modes.
WRITE CLOCK (WCLK)
and hold times must be met with respect to the LOW-to-HIGH transition of
the WCLK. It is permissible to stop the WCLK. Note that while WCLK is idle,
the FF/IR, PAF and HF flags will not be updated. (Note that WCLK is only
capable of updating HF flag to LOW.) The Write and Read Clocks can either
be independent or coincident.
WRITE ENABLE (WEN
array on the rising edge of every WCLK cycle if the device is not full. Data
is stored in the RAM array sequentially and independently of any ongoing
read operation.
n
after three RCLK rising edges, REN = LOW is not necessary. Subse-
Retransmit setup is initiated by holding RT LOW during a rising RCLK edge.
If IDT Standard mode is selected, the FIFO will mark the beginning of
When EF goes HIGH, Retransmit setup is complete and read opera-
If FWFT mode is selected, the FIFO will mark the beginning of the Retransmit
When OR goes LOW, Retransmit setup is complete; at the same time,
This is a dual purpose pin. During Master Reset, the state of the FWFT/SI
If, at the time of Master Reset, FWFT/SI is LOW, then IDT Standard
If, at the time of Master Reset, FWFT/SI is HIGH, then FWFT mode will
After Master Reset, FWFT/SI acts as a serial input for loading PAE and
A write cycle is initiated on the rising edge of the WCLK input. Data setup
When the WEN input is LOW, data may be loaded into the FIFO RAM
WEN
WEN
WEN
WEN)
COMMERCIAL AND INDUSTRIAL
n)
. It also uses Input Ready (IR)
TEMPERATURE RANGES