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IDT72V7270L15 Datasheet(PDF) 9 Page - Integrated Device Technology |
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IDT72V7270L15 Datasheet(HTML) 9 Page - Integrated Device Technology |
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9 / 42 page  9 COMMERCIALTEMPERATURERANGE IDT72V7230/7240/7250/7260/7270/7280/7290/72100 3.3V HIGH DENSITY SUPERSYNC IITM FIFO 512 x 72, 1K x 72, 2K x 72, 4K x 72, 8K x 36, 16K x 72, 32K x 72, 64K x 72 FUNCTIONAL DESCRIPTION TIMING MODES: IDT STANDARD vs FIRST WORD FALL THROUGH (FWFT) MODE The IDT72V7230/72V7240/72V7250/72V7260/72V7270/72V7280/ 72V7290/72V72100 support two different timing modes of operation: IDT Standard mode or First Word Fall Through (FWFT) mode. The selection of which mode will operate is determined during Master Reset, by the state of the FWFT/SI input. 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. It also uses the Full Flag function ( FF) to indicate whether or not the FIFO 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)toindicatewhetherornotthere is valid data at the data outputs (Qn). It also uses Input Ready ( IR) to indicate whether or not the FIFO has any free space for writing. In the FWFT mode, thefirstwordwrittentoanemptyFIFOgoesdirectlytoQnafterthreeRCLKrising edges, REN = LOW is not necessary. Subsequent words must be accessed using the Read Enable ( REN) and RCLK. Varioussignals,bothinputandoutputsignalsoperatedifferentlydepending on which timing mode is in effect. IDT STANDARD MODE In this mode, the status flags, FF, PAF, HF, PAE, and EF operate in the manner outlined in Table 3. To write data into to the FIFO, Write Enable ( WEN) mustbeLOW. DatapresentedtotheDATAINlineswillbeclockedintotheFIFO on subsequent transitions of the Write Clock (WCLK). After the first write is performed, the Empty Flag ( EF)willgoHIGH. Subsequentwriteswillcontinue to fill up the FIFO. The Programmable Almost-Empty flag ( PAE)willgoHIGH after n + 1 words have been loaded into the FIFO, where n is the empty offset value. The default setting for these values are stated in the footnote of Table 2. This parameter is also user programmable. See section on Programmable Flag Offset Loading. If one continued to write data into the FIFO, and we assumed no read operationsweretakingplace,theHalf-Fullflag( HF)wouldtoggletoLOWonce the 257th word for IDT72V7230, 513rd word for IDT72V7240, 1,025th word forIDT72V7250,2,049thwordforIDT72V7260,4,097thwordforIDT72V7270, 8,193th word for the IDT72V7280, 16,385th word for the IDT72V7290 and 32,769th word for the IDT72V72100, respectively was written into the FIFO. ContinuingtowritedataintotheFIFOwillcausetheProgrammableAlmost-Full flag ( PAF)togoLOW. Again,ifnoreadsareperformed, thePAFwillgoLOW after(512-m)writesfortheIDT72V7230,(1,024-m)writesfortheIDT72V7240, (2,048-m) writes for the IDT72V7250, (4,096-m) writes for the IDT72V7260, (8,192-m) writes for the IDT72V7270, (16,384-m) writes for the IDT72V7280, (32,768-m) writes for the IDT72V7290 and (65,536-m) writes for the IDT72V72100. Theoffset“m”isthefulloffsetvalue. Thedefaultsettingforthese values are stated in the footnote of Table 2. This parameter is also user programmable. See section on Programmable Flag Offset Loading. When the FIFO is full, the Full Flag ( FF)willgoLOW,inhibitingfurtherwrite operations. Ifnoreadsareperformedafterareset, FFwillgoLOWafterDwrites to the FIFO. D = 512 writes for the IDT72V7230, 1,024 writes for the IDT72V7240,2,048writesfortheIDT72V7250,4,096writesfortheIDT72V7260, 8,192 writes for the IDT72V7270, 16,384 writes for the IDT72V7280, 32,768 writes for the IDT72V7290, 65,536 writes for the IDT72V72100, respectively. If the FIFO is full, the first read operation will cause FF to go HIGH. Subsequentreadoperationswillcause PAFandHFtogoHIGHattheconditions described in Table 3. If further read operations occur, without write operations, PAE will go LOW when there are n words in the FIFO, where n is the empty offsetvalue. ContinuingreadoperationswillcausetheFIFOtobecomeempty. When the last word has been read from the FIFO, the EFwillgoLOWinhibiting further read operations. REN is ignored when the FIFO is empty. When configured in IDT Standard mode, the EFandFFoutputsaredouble register-bufferedoutputs. Relevant timing diagrams for IDT Standard mode can be found in Figure 10,11,12,16 and 18. FIRST WORD FALL THROUGH MODE (FWFT) In this mode, the status flags, IR, PAF, HF, PAE, and OR operate in the manner outlined in Table 4. To write data into to the FIFO, WENmustbeLOW. DatapresentedtotheDATAINlineswillbeclockedintotheFIFOonsubsequent transitions of WCLK. After the first write is performed, the Output Ready ( OR) flag will go LOW. Subsequent writes will continue to fill up the FIFO. PAEwill goHIGHaftern + 2wordshavebeenloadedintotheFIFO,wherenistheempty offsetvalue. ThedefaultsettingforthesevaluesarestatedinthefootnoteofTable 2. This parameter is also user programmable. See section on Programmable Flag Offset Loading. If one continued to write data into the FIFO, and we assumed no read operationsweretakingplace,the HFwouldtoggletoLOWoncethe258thword for the IDT72V7230, 514th word for the IDT72V7240, 1,026th word for the IDT72V7250, 2,050th word for the IDT72V7260, 4,098th word for the IDT72V7270, 8,194th word for the IDT72V7280, 16,386th word for the IDT72V7290 and 32,770th word for the IDT72V72100, respectively was written into the FIFO. Continuing to write data into the FIFO will cause the PAF togoLOW. Again,ifnoreadsareperformed,the PAFwillgoLOWafter(513-m) writes for the IDT72V7230, (1,025-m) writes for the IDT72V7240, (2,049-m) writesfortheIDT72V7250,(4,097-m)writesfortheIDT72V7260and(8,193-m) writes for the IDT72V7270, 16,385 writes for the IDT72V7280, 32,769 writes for the IDT72V7290 and 65,537 writes for the IDT72V72100, where m is the full offset value. The default setting for these values are stated in the footnote of Table 2. WhentheFIFOisfull,theInputReady( IR)flagwillgoHIGH,inhibitingfurther write operations. If no reads are performed after a reset, IRwillgoHIGHafter D writes to the FIFO. D = 513 writes for the IDT72V7230, 1,025 writes for the IDT72V7240,2,049writesfortheIDT72V7250,4,097writesfortheIDT72V7260 and 8,193 writes for the IDT72V7270, 16,385 writes for the IDT72V7280, 32,769 writes for the IDT72V7290, 65,537 writes for the IDT72V72100, respectively. NotethattheadditionalwordinFWFTmodeisduetothecapacity of the memory plus output register. If the FIFO is full, the first read operation will cause the IR flag to go LOW. Subsequent read operations will cause the PAF and HF to go HIGH at the conditions described in Table 4. If further read operations occur, without write operations,the PAEwillgoLOWwhentherearen+1wordsintheFIFO,where n is the empty offset value. Continuing read operations will cause the FIFO to become empty. When the last word has been read from the FIFO, OR willgo HIGH inhibiting further read operations. REN is ignored when the FIFO is empty. When configured in FWFT mode, the OR flag output is triple register- buffered, and the IR flag output is double register-buffered. RelevanttimingdiagramsforFWFTmodecanbefoundinFigure13,14,15, 17, and 19. |
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