IDT72T36115 Integrated Device Technology, IDT72T36115 Datasheet - Page 56

• Manufacturer Part Number: IDT72T36115
• Description: 128k X 36 Terasync Fifo, 2.5v - Best Value!
• Manufacturer: Integrated Device Technology

Figure 37. Block Diagram of 2,048 x 36, 4,096 x 36, 8,192 x 36, 16,384 x 36, 32,768 x 36, 65,536 x 36, 131,072 x 36, 262,144 x 36 and 524,288 x 36
IDT72T3645/55/65/75/85/95/105/115/125 2.5V TeraSync™ ™ ™ ™ ™ 36-BIT FIFO
1K x 36, 2K x 36, 4K x 36, 8K x 36, 16K x 36, 32K x 36, 64K x 36, 128K x 36 and 256K x 36
DEPTH EXPANSION CONFIGURATION (FWFT MODE ONLY)
greater than 1,024, 2,048 for the IDT72T3655, 4,096 for the IDT72T3665,
8,192 for the IDT72T3675, 16,384 for the IDT72T3685, 32,768 for the
IDT72T3695, 65,536 for the IDT72T36105, 131,072 for the IDT72T36115
and 262,144 for the IDT72T36125 with an 18-bit bus width. In FWFT mode,
the FIFOs can be connected in series (the data outputs of one FIFO connected
to the data inputs of the next) with no external logic necessary. The resulting
configuration provides a total depth equivalent to the sum of the depths
associated with each single FIFO. Figure 37 shows a depth expansion using
two IDT72T3645/72T3655/72T3665/72T3675/72T3685/72T3695/
72T36105/72T36115/72T36125 devices.
in the depth expansion configuration. The first word written to an empty
configuration will pass from one FIFO to the next ("ripple down") until it finally
appears at the outputs of the last FIFO in the chain – no read operation is
necessary but the RCLK of each FIFO must be free-running. Each time the
data word appears at the outputs of one FIFO, that device's OR line goes LOW,
enabling a write to the next FIFO in line.
the last FIFO in the chain to go LOW (i.e. valid data to appear on the last FIFO's
outputs) after a word has been written to the first FIFO is the sum of the delays
for each individual FIFO:
where N is the number of FIFOs in the expansion and T
FWFT/SI
WRITE ENABLE
DATA IN
WRITE CLOCK
INPUT READY
The IDT72T3645 can easily be adapted to applications requiring depths
Care should be taken to select FWFT mode during Master Reset for all FIFOs
For an empty expansion configuration, the amount of time it takes for OR of
n
(N – 1)*(4*transfer clock) + 3*T
Dn
WEN
IR
WCLK
72T36105
72T36115
72T36125
FWFT/SI
72T3645
72T3655
72T3665
72T3675
72T3685
72T3695
IDT
TRANSFER CLOCK
RCLK
REN
RCS
RCLK
OE
OR
Qn
RCLK
is the RCLK
Depth Expansion
GND
n
56
period. Note that extra cycles should be added for the possibility that the t
specification is not met between WCLK and transfer clock, or RCLK and transfer
clock, for the OR flag.
depth expansion configuration. There will be no delay evident for subsequent
words written to the configuration.
configuration will "bubble up" from the last FIFO to the previous one until it finally
moves into the first FIFO of the chain. Each time a free location is created in one
FIFO of the chain, that FIFO's IR line goes LOW, enabling the preceding FIFO
to write a word to fill it.
FIFO in the chain to go LOW after a word has been read from the last FIFO is
the sum of the delays for each individual FIFO:
where N is the number of FIFOs in the expansion and T
period. Note that extra cycles should be added for the possibility that the t
specification is not met between RCLK and transfer clock, or WCLK and transfer
clock, for the IR flag.
is faster. Both these actions result in data moving, as quickly as possible, to the
end of the chain and free locations to the beginning of the chain.
The "ripple down" delay is only noticeable for the first word written to an empty
The first free location created by reading from a full depth expansion
For a full expansion configuration, the amount of time it takes for IR of the first
The Transfer Clock line should be tied to either WCLK or RCLK, whichever
WCLK
IR
Dn
WEN
(N – 1)*(3*transfer clock) + 2 T
72T36105
72T36115
72T36125
72T3645
72T3655
72T3665
72T3675
72T3685
72T3695
FWFT/SI
IDT
COMMERCIAL AND INDUSTRIAL
RCLK
REN
RCS
OR
TEMPERATURE RANGES
OE
Qn
READ CHIP SELECT
OUTPUT ENABLE
JANUARY 11, 2007
n
WCLK
OUTPUT READY
WCLK
READ ENABLE
READ CLOCK
DATA OUT
5907 drw42
is the WCLK
SKEW1
SKEW1