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參數(shù)資料
| 型號： | IDT72255LA20PFI8 |
| 廠商： | IDT, Integrated Device Technology Inc |
| 文件頁數(shù)： | 4/27頁 |
| 文件大小： | 0K |
| 描述： | IC FIFO 8KX18 LP 20NS 64QFP |
| 標(biāo)準(zhǔn)包裝： | 750 |
| 系列： | 7200 |
| 功能： | 同步 |
| 存儲容量： | 144K（8K x 18） |
| 訪問時間： | 20ns |
| 電源電壓： | 4 V ~ 5.5 V |
| 工作溫度： | -40°C ~ 85°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 64-LQFP |
| 供應(yīng)商設(shè)備封裝： | 64-TQFP（14x14） |
| 包裝： | 帶卷 (TR) |
| 其它名稱： | 72255LA20PFI8 |
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12
IDT72255LA/72265LA CMOS SuperSync FIFO
8,192 x 18 and 16,384 x 18
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
JANUARY 13, 2009
SIGNALDESCRIPTION
INPUTS:
DATA IN (D0 - D17)
Data inputs for 18-bit wide data.
CONTROLS:
MASTER RESET (
MRS)
A Master Reset is accomplished whenever the
MRS input is taken to 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.
If FWFT is LOW during Master Reset then the IDT Standard mode,
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.
If
LD is LOW during Master Reset, then PAE is assigned a threshold 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.
If
LD is HIGH during Master Reset, then PAE is assigned a threshold
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.
Parallel reading of the registers is always permitted. (See section
describing the
LD pin for further details.)
During a Master Reset, the output register is initialized to all zeroes. A
Master Reset is required after power up, before a write operation can take
place.
MRS is asynchronous.
See Figure 5, Master Reset Timing, for the relevant timing diagram.
PARTIAL RESET (
PRS)
A Partial Reset is accomplished whenever the
PRS input is taken to a
LOW 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.
Whichever mode is active at the time of Partial Reset, IDT Standard mode
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.
Following Partial Reset, all values held in the offset registers remain
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.
A Partial Reset is useful for resetting the device during the course of
operation, when reprogramming partial flag offset settings may not be
convenient.
See Figure 6, Partial Reset Timing, for the relevant timing diagram.
RETRANSMIT (
RT)
The Retransmit operation allows data that has already been read to be
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 beginning of
the memory.
Retransmit setup is initiated by holding
RT LOW during a rising RCLK
edge.
REN and WEN must be HIGH before bringing RT LOW.
If IDT Standard mode is selected, the FIFO will mark the beginning of 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.
When
EF goes HIGH, Retransmit setup is complete and read operations
may begin starting with the first location in memory. Since IDT Standard
mode is selected, every word read including the first word following Re-
transmit 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.
If FWFT mode is selected, the FIFO will mark the beginning of the Re-
transmit setup by setting
OR HIGH. During this period, the internal read
pointer is set to the first location of the RAM array.
When
OR goes LOW, Retransmit setup is complete; at the same time, 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 neces-
sary. 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)
This is a dual purpose pin. During Master Reset, the state of the FWFT/
SI input determines whether the device will operate in IDT Standard mode
or First Word Fall Through (FWFT) mode.
If, at the time of Master Reset, FWFT/SI is LOW, then IDT Standard 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.
If, at the time of Master Reset, FWFT/SI is HIGH, then FWFT mode will
be selected. This mode uses Output Ready (
OR) to indicate whether or not
there is valid data at the data outputs (Qn). It also uses Input Ready (
IR) 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 Qn
after three RCLK rising edges,
REN = LOW is not necessary. Subsequent
words must be accessed using the Read Enable (
REN) and RCLK.
After Master Reset, FWFT/SI acts as a serial input for loading
PAE and
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)
A write cycle is initiated on the rising edge of the WCLK input. Data setup
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.
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| IDT72255LA20TF | 功能描述:IC FIFO 8KX18 LP 20NS 64QFP RoHS:否 類別:集成電路 (IC) >> 邏輯 - FIFO 系列:7200 標(biāo)準(zhǔn)包裝:90 系列:7200 功能:同步 存儲容量:288K（16K x 18） 數(shù)據(jù)速率:100MHz 訪問時間:10ns 電源電壓:4.5 V ~ 5.5 V 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:64-LQFP 供應(yīng)商設(shè)備封裝:64-TQFP（14x14） 包裝:托盤 其它名稱:72271LA10PF |
| IDT72255LA20TF8 | 功能描述:IC FIFO 8KX18 LP 20NS 64QFP RoHS:否 類別:集成電路 (IC) >> 邏輯 - FIFO 系列:7200 標(biāo)準(zhǔn)包裝:90 系列:7200 功能:同步 存儲容量:288K（16K x 18） 數(shù)據(jù)速率:100MHz 訪問時間:10ns 電源電壓:4.5 V ~ 5.5 V 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:64-LQFP 供應(yīng)商設(shè)備封裝:64-TQFP（14x14） 包裝:托盤 其它名稱:72271LA10PF |
| IDT72255LA20TFI | 功能描述:IC FIFO 8KX18 LP 20NS 64QFP RoHS:否 類別:集成電路 (IC) >> 邏輯 - FIFO 系列:7200 標(biāo)準(zhǔn)包裝:90 系列:7200 功能:同步 存儲容量:288K（16K x 18） 數(shù)據(jù)速率:100MHz 訪問時間:10ns 電源電壓:4.5 V ~ 5.5 V 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:64-LQFP 供應(yīng)商設(shè)備封裝:64-TQFP（14x14） 包裝:托盤 其它名稱:72271LA10PF |
| IDT72255LA20TFI8 | 功能描述:IC FIFO 8KX18 LP 20NS 64QFP RoHS:否 類別:集成電路 (IC) >> 邏輯 - FIFO 系列:7200 標(biāo)準(zhǔn)包裝:90 系列:7200 功能:同步 存儲容量:288K（16K x 18） 數(shù)據(jù)速率:100MHz 訪問時間:10ns 電源電壓:4.5 V ~ 5.5 V 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:64-LQFP 供應(yīng)商設(shè)備封裝:64-TQFP（14x14） 包裝:托盤 其它名稱:72271LA10PF |
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