72255LA20TF IDT, 72255LA20TF Datasheet

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... RESET LOGIC P RS IDT and the IDT logo are registered trademarks of Integrated Device Technology, Inc. SuperSync FIFO is a trademark of Integrated Device Technology, Inc COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES © 2009 Integrated Device Technology, Inc. All rights reserved. Product specifications subject to change without notice. ...

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... There are two possible timing modes of operation with these devices: IDT Standard mode and First Word Fall Through (FWFT) mode. In IDT Standard mode, the first word written to an empty FIFO will not appear on the data output lines unless a specific read operation is performed. A read operation, which consists of activating REN and enabling a rising RCLK edge, will shift the word from internal memory to the data output lines ...

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... During Master Reset (MRS) the following events occur: The read and write pointers are set to the first location of the FIFO. The FWFT pin selects IDT Standard mode or FWFT mode. The LD pin selects either a partial flag default setting of 127 with parallel programming or a partial flag default setting of 1,023 with serial programming ...

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... In the FWFT mode, the IR function is selected. IR indicates whether or not there is space available for writing to the FIFO memory. In the IDT Standard mode, the EF function is selected. EF indicates whether or not the FIFO O memory is empty. In FWFT mode, the OR function is selected. OR indicates whether or not there is valid data available at the outputs ...

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... IDT72255LA/72265LA CMOS SuperSync FIFO™ 8,192 x 18 and 16,384 x 18 ABSOLUTE MAXIMUM RATINGS Symbol Rating V Terminal Voltage TERM with respect to GND T Storage STG Temperature I DC Output Current OUT NOTE: 1. Stresses greater than those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied ...

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... Re-transmit operation NOTES: 1. All AC timings apply to both Standard IDT mode and First Word Fall Through mode. 2. Industrial temperature range product for 15ns and 20ns speed grades are available as a standard device. 3. Pulse widths less than minimum values are not allowed. ...

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... When the FIFO is full, the Input Ready (IR) flag will go HIGH, inhibiting further write operations reads are performed after a reset, IR will go HIGH after D writes to the FIFO 8,193 writes for the IDT72255LA and 16,385 writes for the IDT72265LA, respectively. Note that the additional word in FWFT mode is due to the capacity of the memory plus output register ...

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... PROGRAMMING FLAG OFFSETS Full and Empty Flag offset values are user programmable. The IDT72255LA/72265LA has internal registers for these offsets. Default set- tings are stated in the footnotes of Table 1 and Table 2. Offset values can be programmed into the FIFO in one of two ways; serial or parallel loading method ...

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... NOTES: 1. The programming method can only be selected at Master Reset. 2. Parallel reading of the offset registers is always permitted regardless of which programming method has been selected. 3. The programming sequence applies to both IDT Standard and FWFT modes. Figure 4. Programmable Flag Offset Programming Sequence Figure 3 ...

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... words should have been written into the FIFO between Reset (Master or Partial) and the time of Retransmit setup 8,192 for the IDT72255LA and D = 16,384 for the IDT72265LA. In FWFT mode 8,193 for the IDT72255LA and D = 16,385 for the IDT72265LA ...

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... RCLK. See Figure 12, Retransmit Timing (FWFT Mode), for the relevant timing diagram. For either IDT Standard mode or FWFT mode, updating of the PAE, HF and PAF flags begin with the rising edge of RCLK that RT is setup. PAE is synchronized to RCLK, thus on the second rising edge of RCLK COMMERCIAL AND INDUSTRIAL after RT is setup, the PAE flag will be updated ...

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... 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 ...

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... IR goes HIGH, inhibiting further write operations reads are performed after a reset (either MRS or PRS), IR will go after the valid WCLK cycle. HIGH after D writes to the FIFO (D = 8,193 for the IDT72255LA and 16,385 for the IDT72265LA) See Figure 9, Write Timing (FWFT Mode), for the relevant timing information. ...

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... RCLK edge that accomplishes this condition sets HF HIGH. In IDT Standard mode reads are performed after reset (MRS or PRS), HF will go LOW after (D writes to the FIFO, where D = 8,192 for the IDT72255LA and 16,384 for the IDT72265LA. ...

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... IDT72255LA/72265LA CMOS SuperSync FIFO™ 8,192 x 18 and 16,384 x 18 MRS REN WEN t FWFT FWFT/ SEN EF/OR FF/IR PAE PAF RSS t RSS t RSS t RSS t RSS If FWFT = HIGH HIGH t RSF If FWFT = LOW LOW t If FWFT = LOW HIGH RSF If FWFT = HIGH LOW ...

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... IDT72255LA/72265LA CMOS SuperSync FIFO™ 8,192 x 18 and 16,384 x 18 PRS REN WEN RT SEN EF/OR FF/IR PAE PAF RSS t RSS t RSS t RSS If FWFT = HIGH HIGH t RSF If FWFT = LOW LOW If FWFT = LOW HIGH t RSF If FWFT = HIGH LOW t RSF t RSF t RSF Figure 6 ...

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... WCLK edge and a rising RCLK edge to guarantee that EF will go HIGH (after one RCLK cycle plus SKEW3 rising edge of WCLK and the rising edge of RCLK is less than HIGH. 3. First word latency: 60ns + REF TRCLK Figure 8. Read Cycle, Empty Flag and First Data Word Latency Timing (IDT Standard Mode) t CLK t CLKH t CLKL ...

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... IDT72255LA/72265LA CMOS SuperSync FIFO™ 8,192 x 18 and 16,384 x 18 COMMERCIAL AND INDUSTRIAL 18 TEMPERATURE RANGES JANUARY 13, 2009 ...

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... IDT72255LA/72265LA CMOS SuperSync FIFO™ 8,192 x 18 and 16,384 x 18 COMMERCIAL AND INDUSTRIAL 19 TEMPERATURE RANGES JANUARY 13, 2009 ...

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... FIFO after Master Reset more than D –2 may be written to the FIFO between Reset (Master or Partial) and Retransmit setup. Therefore, FF will be HIGH throughout the Retransmit setup procedure 8,192 for IDT72255LA and 16,384 for IDT72265LA goes HIGH RCLK cycle + t REF ...

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... OR goes LOW RCLK cycles + t REF WCLK t ENS t LDS BIT 0 NOTE for the IDT72255LA and for the IDT72265LA. Figure 13. Serial Loading of Programmable Flag Registers (IDT Standard and FWFT Modes x+1 t SKEW4 ENH t REF t HF ...

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... PAF offset maximum FIFO depth. In IDT Standard mode 8,192 for the IDT72255LA and 16,384 for the IDT72265LA. In FWFT mode 8,193 for the IDT72255LA and 16,385 for the IDT72265LA. is the minimum time between a rising RCLK edge and a rising WCLK edge to guarantee that PAF will go HIGH (after one WCLK cycle plus t 3 ...

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... Figure 17. Programmable Almost-Empty Flag Timing (IDT Standard and FWFT Modes) WCLK D/2 words in FIFO [ + 1 RCLK NOTES: 1. For IDT Standard mode maximum FIFO depth. 2. For FWFT mode maximum FIFO depth 8,193 for the IDT72255LA and 16,385 for the IDT72265LA. Figure 18. Half-Full Flag Timing (IDT Standard and FWFT Modes) (4) t PAE 2 t ENS , then the PAE deassertion may be delayed one extra RCLK cycle ...

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... Use an AND gate in IDT Standard mode gate in FWFT mode not connect any output control signals directly together. 3. FIFO #1 and FIFO #2 must be the same depth, but may be different word widths. Figure 19. Block Diagram of 8,192 x 36 and 16,384 x 36 Width Expansion ...

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... The IDT72255LA can easily be adapted to applications requiring depths greater than 8,192 and 16,384 for the IDT72265LA 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 ...

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... Slim Thin Quad Flatpack (STQFP, PP64-1) TF Commercial Only 10 Clock Cycle Time (t Com'l & Ind'l 15 Speed in Nanoseconds 20 Com‘l & Ind’l LA Low Power 8,192 x 18 — SuperSync FIFO 72255 16,384 x 18 — SuperSync FIFO 72265 for Tech Support: email: FIFOhelp@idt.com ) CLK 4670 drw24 408-360-1753 ...

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... CC A IDT and the IDT logo are registered trademarks of Integrated Device Technology, Inc and the SuperSyncFIFO is a trademark of Integrated Device Technology, Inc. COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES ©2009 Integrated Device Technology, Inc. All rights reserved. Product specifications subject to change without notice. ...