CMOS SyncFIFOTM 64 x 9, 256 x 9, 512 x 9, 1,024 x 9, 2,048 x 9, 4,096 x 9, 8,192 x 9 IDT72421, IDT72201 IDT72211, IDT72221 IDT72231, IDT72241 IDT72251 FEATURES: DESCRIPTION: * * * * The IDT72421/72201/72211/72221/72231/72241/72251 SyncFIFOTM are very high-speed, low-power First-In, First-Out (FIFO) memories with clocked read and write controls. These devices have a 64, 256, 512, 1,024, 2,048, 4,096, and 8,192 x 9-bit memory array, respectively. These FIFOs are applicable for a wide variety of data buffering needs such as graphics, local area networks and interprocessor communication. These FIFOs have 9-bit input and output ports. The input port is controlled by a free-running clock (WCLK), and two write enable pins (WEN1, WEN2). Data is written into the Synchronous FIFO on every rising clock edge when the write enable pins are asserted. The output port is controlled by another clock pin (RCLK) and two read enable pins (REN1, REN2). The Read Clock can be tied to the Write Clock for single clock operation or the two clocks can run asynchronous of one another for dual-clock operation. An output enable pin (OE) is provided on the read port for three-state control of the output. The Synchronous FIFOs have two fixed flags, Empty (EF) and Full (FF). Two programmable flags, Almost-Empty (PAE) and Almost-Full (PAF), are provided for improved system control. The programmable flags default to Empty+7 and Full-7 for PAE and PAF, respectively. The programmable flag offset loading is controlled by a simple state machine and is initiated by asserting the load pin (LD). These FIFOs are fabricated using IDT's high-speed submicron CMOS technology. * * * * * * * * * * * * * * 64 x 9-bit organization (IDT72421) 256 x 9-bit organization (IDT72201) 512 x 9-bit organization (IDT72211) 1,024 x 9-bit organization (IDT72221) 2,048 x 9-bit organization (IDT72231) 4,096 x 9-bit organization (IDT72241) 8,192 x 9-bit organization (IDT72251) 10 ns read/write cycle time Read and Write Clocks can be independent Dual-Ported zero fall-through time architecture Empty and Full Flags signal FIFO status Programmable Almost-Empty and Almost-Full flags can be set to any depth Programmable Almost-Empty and Almost-Full flags default to Empty+7, and Full-7, respectively Output enable puts output data bus in high-impedance state Advanced submicron CMOS technology Available in the 32-pin plastic leaded chip carrier (PLCC) and 32-pin Thin Quad Flat Pack (TQFP) For through-hole product please see the IDT72420/72200/72210/ 72220/72230/72240 data sheet Industrial temperature range (-40C to +85C) is available FUNCTIONAL BLOCK DIAGRAM D0 - D8 WCLK WEN1 WEN2 LD INPUT REGISTER OFFSET REGISTER EF PAE PAF FF FLAG LOGIC WRITE CONTROL LOGIC RAM ARRAY 64 x 9, 256 x 9, 512 x 9, 1,024 x 9, 2,048 x 9, 4,096 x 9, 8,192 x 9 WRITE POINTER READ POINTER READ CONTROL LOGIC OUTPUT REGISTER RESET LOGIC RCLK REN1 REN2 RS OE 2655 drw01 Q0 - Q8 The IDT logo is a registered trademark and the SyncFIFO is a trademark of Integrated Device Technology, Inc. COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES MAY 2001 1 2001 Integrated Device Technology, Inc. DSC-2655/1 IDT72421/72201/72211/72221/72231/72241/72251 CMOS SYNCFIFOTM 64 x 9, 256 x 9, 512 x 9, 1,024 x 9, 2,048 x 9, 4,096 x 9, 8,192 x 9 COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES D1 1 24 WEN1 D0 2 23 PAF 3 22 WCLK WEN2/LD PAE GND 4 21 VCC 20 Q8 5 D8 2 D6 3 D7 4 D5 D3 D4 32 31 30 29 28 27 26 25 D2 INDEX RS D7 D8 D6 D5 D4 INDEX D3 D2 PIN CONFIGURATION 32 31 30 1 D1 5 29 RS D0 6 28 WEN1 PAF 7 27 WCLK WEN2/LD PAE 8 26 GND 9 25 10 24 VCC Q8 Q7 REN1 6 19 Q7 REN1 RCLK REN2 7 18 Q6 RCLK 11 23 8 17 Q5 REN2 12 22 Q6 OE 13 21 Q5 TQFP (PR32-1, order code: PF) TOP VIEW Q4 Q3 Q2 Q1 2655 drw 02 FF Q0 14 15 16 17 18 19 20 EF Q4 Q3 Q2 Q1 FF Q0 OE EF 9 10 11 12 13 14 15 16 2655 drw02a PLCC (J32-1, order code: J) TOP VIEW PIN DESCRIPTIONS Symbol Name D0-D8 Data Inputs RS Reset WCLK WEN1 WEN2/ LD Q0-Q8 RCLK Write Enable 2/ Load REN1 Data Outputs Read Clock Read Enable 1 REN2 Read Enable 2 OE Output Enable EF Empty Flag PAE FF Programmable Almost-Empty Flag Programmable Almost-Full Flag Full Flag VCC GND Power Ground PAF Write Clock Write Enable 1 I/O Description I Data inputs for a 9-bit bus. I When RS is set LOW, internal read and write pointers are set to the first location of the RAM array,FF and PAF go HIGH, and PAE and EF go LOW. A reset is required before an initial WRITE after power-up. I Data is written into the FIFO on a LOW-to-HIGH transition of WCLK when the Write Enable(s) are asserted. I If the FIFO is configured to have programmable flags, WEN1 is the only write enable pin. When WEN1 is LOW, data is written into the FIFO on every LOW-to-HIGH transition WCLK. If the FIFO is configured to have two write enables, WEN1 must be LOW and WEN2 must be HIGH to write data into the FIFO. Data will not be written into the FIFO if the FF is LOW. I The FIFO is configured at reset to have either two write enables or programmable flags. If WEN2/ LD is HIGH at reset, this pin operates as a second write enable. If WEN2/LD is LOW at reset, this pin operates as a control to load and read the programmable flag offsets. If the FIFO is configured to have two write enables, WEN1 must be LOW and WEN2 must be HIGH to write data into the FIFO. Data will not be written into the FIFO if the FF is LOW. If the FIFO is configured to have programmable flags, WEN2/LD is held LOW to write or read the programmable flag offsets. O Data outputs for a 9-bit bus. I Data is read from the FIFO on a LOW-to-HIGH transition of RCLK when REN1 and REN2 are asserted. I When REN1 and REN2 are LOW, data is read from the FIFO on every LOW-to-HIGH transition of RCLK. Data will not be read from the FIFO if the EF is LOW. I When REN1 and REN2 are LOW, data is read from the FIFO on every LOW-to-HIGH transition of RCLK. Data will not be read from the FIFO if the EF is LOW. I When OE is LOW, the data output bus is active. If OE is HIGH, the output data bus will be in a high-impedance state. O When EF is LOW, the FIFO is empty and further data reads from the output are inhibited. When EF is HIGH, the FIFO is not empty. EF is synchronized to RCLK. O When PAE is LOW, the FIFO is almost-empty based on the offset programmed into the FIFO. The default offset at reset is Empty+7. PAE is synchronized to RCLK. O When PAF is LOW, the FIFO is almost-full based on the offset programmed into the FIFO. The default offset at reset is Full-7. PAF is synchronized to WCLK. O When FF is LOW, the FIFO is full and further data writes into the input are inhibited. When FF is HIGH, the FIFO is not full. FF is synchronized to WCLK. One +5 volt power supply pin. One 0 volt ground pin. 2 IDT72421/72201/72211/72221/72231/72241/72251 CMOS SYNCFIFOTM 64 x 9, 256 x 9, 512 x 9, 1,024 x 9, 2,048 x 9, 4,096 x 9, 8,192 x 9 ABSOLUTE MAXIMUM RATINGS Symbol VTERM TSTG Rating Terminal Voltage with Respect to GND Storage Temperature IOUT DC Output Current Com'l & Ind'l -0.5 to +7.0 Unit V -55 to +125 C -50 to +50 mA COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES RECOMMENDED OPERATING CONDITIONS Symbol VCC GND VIH 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 the specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability. VIL TA TA Parameter Supply Voltage Commercial/Industrial Supply Voltage Input High Voltage Commercial/Industrial Input Low Voltage Commercial/Industrial Operating Temperature Commercial Operating Temperature Industrial Min. 4.5 Typ. Max. 5.0 5.5 Unit V 0 2.0 0 -- 0 -- V V -- -- 0.8 V 0 -- 70 C -40 -- 85 C DC ELECTRICAL CHARACTERISTICS (Commercial: VCC = 5V 10%, TA = 0C to +70C; Industrial: VCC = 5V 10%, TA = -40C to +85C) IDT72421 IDT72201 IDT72211 IDT72221 IDT72231 IDT72241 Com'l and Ind'l(1) tCLK = 10, 15, 25 ns Symbol Parameter Min. Typ. Max. IDT72251 Com'l and Ind'l(1) tCLK = 10, 15, 25 ns Min. Typ. Max. ILI(2) Input Leakage Current (Any Input) -1 -- 1 -1 -- 1 ILO(3) Output Leakage Current -10 -- 10 -10 -- 10 VOH Output Logic "1" Voltage, IOH = -2mA 2.4 -- -- 2.4 -- -- VOL Output Logic "0" Voltage, IOL = 8mA -- -- 0.4 -- -- 0.4 Active Power Supply Current -- -- 35 -- -- 50 Standby Current -- -- 5 -- -- 5 ICC1(4,5,6) (4,7) ICC2 NOTES: 1. Industrial temperature range product for the 15ns and 25ns speed grades are available as standard product. 2. Measurements with 0.4 VIN VCC. 3. OE VIH, 0.4 VOUT VCC. 4. Tested with outputs open (IOUT = 0). 5. RCLK and WCLK toggle at 20 MHz and data inputs switch at 10 MHz. 6. Typical ICC1 = 1.7 + 0.7*fS + 0.02*CL*fS (in mA). These equations are valid under the following conditions: VCC = 5V, TA = 25C, fS = WCLK frequency = RCLK frequency (in MHz, using TTL levels), data switching at fS/2, CL = capacitive load (in pF). 7. All Inputs = VCC - 0.2V or GND + 0.2V, except RCLK and WCLK, which toggle at 20 MHz. 3 IDT72421/72201/72211/72221/72231/72241/72251 CMOS SYNCFIFOTM 64 x 9, 256 x 9, 512 x 9, 1,024 x 9, 2,048 x 9, 4,096 x 9, 8,192 x 9 COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES AC ELECTRICAL CHARACTERISTICS (Commercial: VCC = 5V 10%, TA = 0C to +70C; Industrial: VCC = 5V 10%, TA = -40C to +85C) Symbol fS tA tCLK tCLKH tCLKL tDS tDH tENS tENH tRS tRSS tRSR tRSF tOLZ tOE tOHZ tWFF tREF tPAF tPAE tSKEW1 tSKEW2 Parameter Clock Cycle Frequency Data Access Time Clock Cycle Time Clock High Time Clock Low Time Data Setup Time Data Hold Time Enable Setup Time Enable Hold Time Reset Pulse Width(2) Reset Setup Time Reset Recovery Time Reset to Flag and Output Time Output Enable to Output in Low-Z(3) Output Enable to Output Valid Output Enable to Output in High-Z(3) Write Clock to Full Flag Read Clock to Empty Flag Write Clock to Programmable Almost-Full Flag Read Clock to Programmable Almost-Empty Flag Skew time between Read Clock & Write Clock for Empty Flag & Full Flag Skew time between Read Clock & Write Clock for Almost-Empty Flag & Programmable Almost-Full Flag Com'l & Ind'l(1) IDT72421L15 IDT72201L15 IDT72211L15 IDT72221L15 IDT72231L15 IDT72241L15 IDT72251L15 Min. Max. -- 66.7 2 10 15 -- 6 -- 6 -- 4 -- 1 -- 4 -- 1 -- 15 -- 10 -- 10 -- -- 15 0 -- 3 8 3 8 -- 10 -- 10 -- 10 -- 10 6 -- Commercial IDT72421L10 IDT72201L10 IDT72211L10 IDT72221L10 IDT72231L10 IDT72241L10 IDT72251L10 Min. Max. -- 100 2 6.5 10 -- 4.5 -- 4.5 -- 3 -- 0.5 -- 3 -- 0.5 -- 10 -- 8 -- 8 -- -- 10 0 -- 3 6 3 6 -- 6.5 -- 6.5 -- 6.5 -- 6.5 5 -- 14 -- 15 -- Com'l & Ind'l(1) IDT72421L25 IDT72201L25 IDT72211L25 IDT72221L25 IDT72231L25 IDT72241L25 IDT72251L25 Min. Max. -- 40 2 15 25 -- 10 -- 10 -- 6 -- 1 -- 6 -- 1 -- 15 -- 15 -- 15 -- -- 25 0 -- 3 13 3 13 -- 15 -- 15 -- 15 -- 15 10 -- 18 -- NOTES: 1. Industrial temperature range product for the 15ns and 25ns speed grades are available as standard product. 2. Pulse widths less than minimum values are not allowed. 3. Values guaranteed by design, not currently tested. AC TEST CONDITIONS In Pulse Levels Input Rise/Fall Times Input Timing Reference Levels Output Reference Levels Output Load 5V GND to 3.0V 3ns 1.5V 1.5V See Figure 1 1.1K D.U.T. 680 CAPACITANCE (Ta = +25C, f = 1.0MHz) Symbol CIN(2) COUT(1,2) Parameter Input Capacitance Output Capacitance Conditions VIN = 0V VOUT = 0V Max. 10 10 Unit pF pF 2655 drw 03 or equivalent circuit NOTES: 1. With output deselected (OE VIH). 2. Characterized values, not currently tested. 30pF* Figure 1. Output Load *includes jig and scope capacitances 4 Unit MHz ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns IDT72421/72201/72211/72221/72231/72241/72251 CMOS SYNCFIFOTM 64 x 9, 256 x 9, 512 x 9, 1,024 x 9, 2,048 x 9, 4,096 x 9, 8,192 x 9 SIGNAL DESCRIPTIONS COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES OUTPUT ENABLE (OE) When Output Enable (OE) is enabled (LOW), the parallel output buffers receive data from the output register. When Output Enable (OE) is disabled (HIGH), the Q output data bus is in a high-impedance state. INPUTS: DATA IN (D0 - D8) Data inputs for 9-bit wide data. WRITE ENABLE 2/LOAD (WEN2/LD) This is a dual-purpose pin. The FIFO is configured at Reset to have programmable flags or to have two write enables, which allows depth expansion. If Write Enable 2/Load (WEN2/LD) is set HIGH at Reset (RS = LOW), this pin operates as a second write enable pin. If the FIFO is configured to have two write enables, when Write Enable (WEN1) is LOW and Write Enable 2/Load (WEN2/LD) is HIGH, data can be loaded into the input register and RAM array on the LOW-to-HIGH transition of every Write Clock (WCLK). Data is stored in the RAM array sequentially and independently of any ongoing read operation. In this configuration, when Write Enable (WEN1) is HIGH and/or Write Enable 2/Load (WEN2/LD) is LOW, the input register holds the previous data and no new data is allowed to be loaded into the register. To prevent data overflow, the Full Flag (FF) will go LOW, inhibiting further write operations. Upon the completion of a valid read cycle, the Full Flag (FF) will go HIGH after tWFF, allowing a valid write to begin. Write Enable 1 (WEN1) and Write Enable 2/Load (WEN2/LD) are ignored when the FIFO is full. The FIFO is configured to have programmable flags when the Write Enable 2/Load (WEN2/LD) is set LOW at Reset (RS=LOW). The IDT72421/72201/ 72211/72221/72231/72241/72251 devices contain four 8-bit offset registers which can be loaded with data on the inputs, or read on the outputs. See Figure 3 for details of the size of the registers and the default values. If the FIFO is configured to have programmable flags when the Write Enable 1 (WEN1) and Write Enable 2/Load (WEN2/LD) are set LOW, data on the inputs D is written into the Empty (Least Significant Bit) Offset register on the first LOWto-HIGH transition of the Write Clock (WCLK). Data is written into the Empty (Most Significant Bit) Offset register on the second LOW-to-HIGH transition of the Write Clock (WCLK), into the Full (Least Significant Bit) Offset register on the third transition, and into the Full (Most Significant Bit) Offset register on the fourth transition. The fifth transition of the Write Clock (WCLK) again writes to the Empty (Least Significant Bit) Offset register. However, writing all offset registers does not have to occur at one time. One or two offset registers can be written and then by bringing the Write Enable 2/ Load (WEN2/LD) pin HIGH, the FIFO is returned to normal read/write operation. When the Write Enable 2/Load (WEN2/LD) pin is set LOW, the Write Enable 1 (WEN1) is LOW, the next offset register in sequence is written. CONTROLS: RESET (RS) Reset is accomplished whenever the Reset (RS) input is taken to a LOW state. During reset, both internal read and write pointers are set to the first location. A reset is required after power-up before a write operation can take place. The Full Flag (FF) and Programmable Almost-Full flag (PAF) will be reset to HIGH after tRSF. The Empty Flag (EF) and Programmable Almost-Empty flag (PAE) will be reset to LOW after tRSF. During reset, the output register is initialized to all zeros and the offset registers are initialized to their default values. WRITE CLOCK (WCLK) A write cycle is initiated on the LOW-to-HIGH transition of the Write Clock (WCLK). Data setup and hold times must be met in respect to the LOW-to-HIGH transition of WCLK. The Full Flag (FF) and Programmable Almost-Full flag (PAF) are synchronized with respect to the LOW-to-HIGH transition of WCLK. The Write and Read Clocks can be asynchronous or coincident. WRITE ENABLE 1 (WEN1) If the FIFO is configured for programmable flags, Write Enable 1 (WEN1) is the only enable control pin. In this configuration, when Write Enable 1 (WEN1) is LOW, data can be loaded into the input register and RAM array on the LOWto-HIGH transition of every Write Clock (WCLK). Data is stored in the RAM array sequentially and independently of any ongoing read operation. In this configuration, when Write Enable 1 (WEN1) is HIGH, the input register holds the previous data and no new data is allowed to be loaded into the register. If the FIFO is configured to have two write enables, which allows for depth expansion, there are two enable control pins. See Write Enable 2 paragraph below for operation in this configuration. To prevent data overflow, the Full Flag (FF) will go LOW, inhibiting further write operations. Upon the completion of a valid read cycle, the Full Flag (FF) will go HIGH after tWFF, allowing a valid write to begin. Write Enable 1 (WEN1) is ignored when the FIFO is full. READ CLOCK (RCLK) Data can be read on the outputs on the LOW-to-HIGH transition of the Read Clock (RCLK). The Empty Flag (EF) and Programmable Almost-Empty flag (PAE) are synchronized with respect to the LOW-to-HIGH transition of RCLK. The Write and Read Clocks can be asynchronous or coincident. READ ENABLES (REN1, REN2) When both Read Enables (REN1, REN2) are LOW, data is read from the RAM array to the output register on the LOW-to-HIGH transition of the Read Clock (RCLK). When either Read Enable (REN1, REN2) is HIGH, the output register holds the previous data and no new data is allowed to be loaded into the register. When all the data has been read from the FIFO, the Empty Flag (EF) will go LOW, inhibiting further read operations. Once a valid write operation has been accomplished, the Empty Flag (EF) will go HIGH after tREF and a valid read can begin. The Read Enables (REN1, REN2) are ignored when the FIFO is empty. LD WEN1 0 0 0 1 1 0 No Operation Write Into FIFO 1 1 No Operation WCLK Selection Empty Offset (LSB) Empty Offset (MSB) Full Offset (LSB) Full Offset (MSB) NOTE: 1. For the purposes of this table, WEN2 = VIH. 2. The same selection sequence applies to reading from the registers. REN1 and REN2 are enabled and read is performed on the LOW-to-HIGH transition of RCLK. Figure 2. Write Offset Register 5 IDT72421/72201/72211/72221/72231/72241/72251 CMOS SYNCFIFOTM 64 x 9, 256 x 9, 512 x 9, 1,024 x 9, 2,048 x 9, 4,096 x 9, 8,192 x 9 The contents of the offset registers can be read on the output lines when the Write Enable 2/Load (WEN2/LD) pin is set LOW and both Read Enables (REN1, REN2) are set LOW. Data can be read on the LOW-to-HIGH transition of the Read Clock (RCLK). COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES A read and write should not be performed simultaneously to the offset registers. IDT72421 - 64 x 9-BIT 8 IDT72201 - 256 x 9-BIT 6 5 0 Empty Offset (LSB) Reg. 8 7 Default Value 007H Default Value 007H 8 6 5 8 0 8 0 8 0 7 Full Offset (LSB) Reg. Default Value 007H 8 0 8 0 8 0 IDT72221 - 1,024 x 9-BIT 7 7 0 Empty Offset (LSB) Reg. Empty Offset (LSB) Default Value 007H Default Value 007H 1 8 0 Full Offset (LSB) Reg. Default Value 007H IDT72211 - 512 x 9-BIT 8 0 Empty Offset (LSB) Reg. 8 0 0 1 (MSB) (MSB) 00 0 7 8 8 0 7 8 Default Value 007H 1 7 8 0 (MSB) 0 00 8 7 Empty Offset (LSB) Reg. Default Value 007H 8 8 2 0 0 8 7 0 Empty Offset (LSB) Empty Offset (LSB) Default Value 007H Default Value 007H 8 3 0 8 4 0 (MSB) (MSB) (MSB) 000 0000 00000 7 0 8 7 0 8 Full Offset (LSB) Full Offset (LSB) Reg. Default Value 007H 8 IDT72251 8,192 x 9-BIT IDT72241 - 4,096 x 9-BIT 0 0 1 (MSB) IDT72231 - 2,048 x 9-BIT 8 0 Full Offset (LSB) Reg. Full Offset (LSB) Default Value 007H 0 8 3 0 Full Offset (LSB) Default Value 007H 2 7 Default Value 007H 0 8 4 0 (MSB) (MSB) (MSB) 000 0000 00000 2655 drw 05 Figure 3. Offset Register Location and Default Values 6 IDT72421/72201/72211/72221/72231/72241/72251 CMOS SYNCFIFOTM 64 x 9, 256 x 9, 512 x 9, 1,024 x 9, 2,048 x 9, 4,096 x 9, 8,192 x 9 OUTPUTS: COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES (1,024-m) writes for the IDT72221, (2,048-m) writes for the IDT72231, (4,096m) writes for the IDT72241, and (8,192-m) writes for the IDT72251. The offset "m" is defined in the Full offset registers. If there is no Full offset specified, the Programmable Almost-Full flag (PAF) will go LOW at Full-7 words. The Programmable Almost-Full flag (PAF) is synchronized with respect to the LOW-to-HIGH transition of the Write Clock (WCLK). FULL FLAG (FF) The Full Flag (FF) will go LOW, inhibiting further write operation, when the device is full. If no reads are performed after Reset (RS), the Full Flag (FF) will go LOW after 64 writes for the IDT72421, 256 writes for the IDT72201, 512 writes for the IDT72211, 1,024 writes for the IDT72221, 2,048 writes for the IDT72231, 4,096 writes for the IDT72241, and 8,192 writes for the IDT72251. The Full Flag (FF) is synchronized with respect to the LOW-to-HIGH transition of the Write Clock (WCLK). PROGRAMMABLE ALMOST-EMPTY FLAG (PAE) The Programmable Almost-Empty flag (PAE) will go LOW when the read pointer is "n+1" locations less than the write pointer. The offset "n" is defined in the Empty Offset registers. If no reads are performed after Reset the Programmable Almost-Empty flag (PAE) will go HIGH after "n+1" for the IDT72421/72201/72211/72221/72231/72241/72251. If there is no Empty offset specified, the Programmable Almost-Empty flag (PAE) will go LOW at Empty+7 words. The Programmable Almost-Empty flag (PAE) is synchronized with respect to the LOW-to-HIGH transition of the Read Clock (RCLK). EMPTY FLAG (EF) The Empty Flag (EF) will go LOW, inhibiting further read operations, when the read pointer is equal to the write pointer, indicating the device is empty. The Empty Flag (EF) is synchronized with respect to the LOW-to-HIGH transition of the Read Clock (RCLK). PROGRAMMABLE ALMOST-FULL FLAG (PAF) The Programmable Almost-Full flag (PAF) will go LOW when the FIFO reaches the almost-full condition. If no reads are performed after Reset (RS), the Programmable Almost-Full flag (PAF) will go LOW after (64-m) writes for the IDT72421, (256-m) writes for the IDT72201, (512-m) writes for the IDT72211, DATA OUTPUTS (Q0 - Q8) Data outputs for a 9-bit wide data. TABLE 1 STATUS FLAGS NUMBER OF WORDS IN FIFO IDT72201 0 1 to n (1) IDT72421 0 1 to n (1) (n+1) to (64-(m+1)) (64-m)(2) to 63 64 (n+1) to (256-(m+1)) (256-m)(2) to 255 256 IDT72211 0 1 to n (1) FF H H PAF H H PAE L L EF L H (n+1) to (512-(m+1)) (512-m)(2) to 511 512 H H L H L L H H H H H H 2655 tbl 09 NUMBER OF WORDS IN FIFO IDT72221 IDT72231 IDT72241 IDT72251 FF PAF PAE EF 0 0 0 0 H H L L H H L H H H H H (1) (1) 1 to n 1 to n (n+1) to (1,024-(m+1)) (2) (n+1) to (2,048-(m+1)) (2) (1) (1) 1 to n 1 to n (n+1) to (4,096-(m+1)) (2) (2) (1,024-m) to 1,023 (2,048-m) to 2,047 (4,096-m) to 4,095 (8,192-m) to 8,191 H L H H 1,024 2,048 4,096 8,192 L L H H NOTES: 1. n = Empty Offset (n = 7 default value) 2. m = Full Offset (m = 7 default value) (n+1) to (8,192-(m+1)) 7 IDT72421/72201/72211/72221/72231/72241/72251 CMOS SYNCFIFOTM 64 x 9, 256 x 9, 512 x 9, 1,024 x 9, 2,048 x 9, 4,096 x 9, 8,192 x 9 COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES tRS RS tRSS tRSR tRSS tRSR tRSS tRSR REN1, REN2 WEN1 WEN2/LD (1) tRSF EF, PAE tRSF FF, PAF tRSF OE = 1 (2) Q0 - Q8 OE = 0 2655 drw 06 NOTES: 1. Holding WEN2/LD HIGH during reset will make the pin act as a second write enable pin. Holding WEN2/LD LOW during reset will make the pin act as a load enable for the programmable flag offset registers. 2. After reset, the outputs will be LOW if OE = 0 and tri-state if OE = 1. 3. The clocks (RCLK, WCLK) can be free-running during reset. Figure 4. Reset Timing tCLK tCLKH tCLKL WCLK tDH tDS D0 - D8 DATA IN VALID tENS tENH NO OPERATION WEN1 tENS tENH WEN2/ (If Applicable) NO OPERATION tWFF tWFF FF tSKEW1(1) RCLK REN1, REN2 2655 drw 07 NOTE: 1. tSKEW1 is the minimum time between a rising RCLK edge and a rising WCLK edge for FF to change during the current clock cycle. If the time between the rising edge of RCLK and the rising edge of WCLK is less than tSKEW1, then FF may not change state until the next WCLK edge. Figure 5. Write Cycle Timing 8 IDT72421/72201/72211/72221/72231/72241/72251 CMOS SYNCFIFOTM 64 x 9, 256 x 9, 512 x 9, 1,024 x 9, 2,048 x 9, 4,096 x 9, 8,192 x 9 COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES tCLK tCLKH tCLKL RCLK tENS tENH REN1, REN2 NO OPERATION tREF tREF EF tA VALID DATA Q0 - Q8 tOLZ tOHZ tOE OE (1) tSKEW1 WCLK WEN1 2655 drw 08 WEN2 NOTE: 1. tSKEW1 is the minimum time between a rising WCLK edge and a rising RCLK edge for EF to change during the current clock cycle. If the time between the rising edge of RCLK and the rising edge of WCLK is less than tSKEW1, then EF may not change state until the next RCLK edge. Figure 6. Read Cycle Timing WCLK tDS D0 - D8 D1 tENS D2 D3 D0 (First Valid Write) WEN1 tENS WEN2 (If Applicable) tFRL (1) tSKEW1 RCLK tREF EF tENS REN1, REN2 tA Q0 - Q8 tA D0 tOLZ D1 tOE OE NOTE: 1. When tSKEW1 minimum specification, tFRL = tCLK + tSKEW1 When tSKEW1 < minimum specification, tFRL = 2tCLK + tSKEW1 or tCLK + tSKEW1 The Latency Timings apply only at the Empty Boundary (EF = LOW). 2655 drw 09 Figure 7. First Data Word Latency Timing 9 IDT72421/72201/72211/72221/72231/72241/72251 CMOS SYNCFIFOTM 64 x 9, 256 x 9, 512 x 9, 1,024 x 9, 2,048 x 9, 4,096 x 9, 8,192 x 9 COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES NO WRITE NO WRITE NO WRITE WCLK tSKEW1 tDS tSKEW1 D0 - D8 tWFF tWFF tWFF FF (1) tENS tENH tENS tENS tENH tENS WEN1 (1) WEN2 (If Applicable) RCLK tENH tENS REN1, REN2 tENS tENH tA OE LOW tA Q0 - Q8 DATA IN OUTPUT REGISTER DATA READ NEXT DATA READ 2655 drw 10 NOTE: 1. Only one of the two write enable inputs, WEN1 or WEN2, needs to go inactive to inhibit writes to the FIFO. Figure 8. Full Flag Timing WCLK tDS D0 - D8 tDS DATA WRITE 1 tENS DATA WRITE 2 tENH tENS tENH tENS tENH WEN1 tENS tENH WEN2 (If Applicable) (1) tSKEW1 (1) tFRL tSKEW1 tFFL RCLK tREF tREF tREF EF REN1, REN2 OE LOW tA Q0 - Q8 DATA IN OUTPUT REGISTER DATA READ 2655 drw 11 NOTE: 1. When tSKEW1 minimum specification, tFRL maximum = tCLK + tSKEW1 When tSKEW1 < minimum specification, tFRL maximum = 2tCLK + tSKEW1 or tCLK+ tSKEW1 The Latency Timings apply only at the Empty Boundary (EF = LOW). Figure 9. Empty Flag Timing 10 IDT72421/72201/72211/72221/72231/72241/72251 CMOS SYNCFIFOTM 64 x 9, 256 x 9, 512 x 9, 1,024 x 9, 2,048 x 9, 4,096 x 9, 8,192 x 9 tCLKH tCLKL COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES (4) WCLK tENS tENH tENS tENH WEN1 WEN2 (If Applicable) tPAF PAF Full - (m+1) words in FIFO (1) (2) Full - m words in FIFO (3) tSKEW2 tPAF RCLK tENH tENS REN1, REN2 2655 drw 12 NOTES: 1. m = PAF offset . 2. 64-m words in FIFO for IDT72421, 256-m words for IDT72201, 512-m words for IDT72211, 1,024-m words for IDT72221, 2,048-m words for IDT72231, 4,096-m words for IDT72241, and 8,192-m words for IDT72251. 3. tSKEW2 is the minimum time between a rising RCLK edge and a rising WCLK edge for PAF to change during that clock cycle. If the time between the rising edge of RCLK and the rising edge of WCLK is less than tSKEW2, then PAF may not change state until the next WCLK rising edge. 4. If a write is performed on this rising edge of the Write Clock, there will be Full - (m-1) words in the FIFO when PAF goes LOW. Figure 10. Programmable Full Flag Timing tCLKH tCLKL WCLK tENS tENH tENS tENH WEN1 WEN2 (If Applicable) PAE n+1 words in FIFO n words in FIFO (1) tSKEW2 (2) tPAE tPAE (3) RCLK tENS REN1, REN2 tENH 2655 drw 13 NOTES: 1. n = PAE offset. 2. tSKEW2 is the minimum time between a rising WCLK edge and a rising RCLK edge for PAE to change during that clock cycle. If the time between the rising edge of WCLK and the rising edge of RCLK is less than tSKEW2, then PAE may not change state until the next RCLK rising edge. 3. If a read is performed on this rising edge of the Read Clock, there will be Empty + (n-1) words in the FIFO when PAE goes LOW. Figure 11. Programmable Empty Flag Timing 11 IDT72421/72201/72211/72221/72231/72241/72251 CMOS SYNCFIFOTM 64 x 9, 256 x 9, 512 x 9, 1,024 x 9, 2,048 x 9, 4,096 x 9, 8,192 x 9 COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES tCLK tCLKH tCLKL WCLK tENS tENH LD tENS WEN1 tDS tDH D0 - D7 PAE OFFSET (LSB) PAE OFFSET (MSB) PAF OFFSET (LSB) PAF OFFSET (MSB) 2655 drw 14 Figure 12. Write Offset Registers Timing tCLK tCLKH tCLKL RCLK tENS tENH LD tENS REN1, REN2 tA Q0 - Q7 DATA IN OUTPUT REGISTER EMPTY OFFSET (LSB) EMPTY OFFSET (MSB) FULL OFFSET (LSB) FULL OFFSET (MSB) Figure 13. Read Offset Registers Timing 12 2655 drw15 IDT72421/72201/72211/72221/72231/72241/72251 CMOS SYNCFIFOTM 64 x 9, 256 x 9, 512 x 9, 1,024 x 9, 2,048 x 9, 4,096 x 9, 8,192 x 9 OPERATING CONFIGURATIONS COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES configuration, the Write Enable 2/Load (WEN2/LD) pin is set LOW at Reset so that the pin operates as a control to load and read the programmable flag offsets. SINGLE DEVICE CONFIGURATION A single IDT72421/72201/72211/72221/72231/72241/72251 may be used when the application requirements are for 64/256/512/1,024/2,048/4,096/ 8,192 words or less. When these FIFOs are in a Single Device Configuration, the Read Enable 2 (REN2) control input can be grounded (see Figure 14). In this configuration, the Write Enable 2/Load (WEN2/LD) pin is set LOW at Reset so that the pin operates as a control to load and read the programmable flag offsets. DEPTH EXPANSION - The IDT72421/72201/72211/72221/72231/72241/ 72251 can be adapted to applications when the requirements are for greater than 64/256/512/1,024/2,048/4,096/8,192 words. The existence of two enable pins on the read and write port allow depth expansion. The Write Enable 2/Load pin is used as a second write enable in a depth expansion configuration thus the Programmable flags are set to the default values. Depth expansion is possible by using one enable input for system control while the other enable input is controlled by expansion logic to direct the flow of data. A typical application would have the expansion logic alternate data access from one device to the next in a sequential manner. These devices operate in the Depth Expansion configuration when the following conditions are met: 1. The WEN2/ LD pin is held HIGH during Reset so that this pin operates a second Write Enable. 2. External logic is used to control the flow of data. Please see the Application Note "DEPTH EXPANSION OF IDT'S SYNCHRONOUS FIFOs USING THE RING COUNTER APPROACH" for details of this configuration. WIDTH EXPANSION CONFIGURATION Word width may be increased simply by connecting the corresponding input controls signals of multiple devices. A composite flag should be created for each of the endpoint status flags (EF and FF). The partial status flags (AE and AF) can be detected from any one device. Figure 15 demonstrates a 18-bit word width by using two IDT72421/72201/72211/72221/72231/72241/72251s. Any word width can be attained by adding additional IDT72421/72201/72211/ 72221/72231/72241/72251s. When these FIFOs are in a Width Expansion Configuration, the Read Enable 2 (REN2) control input can be grounded (see Figure 15). In this RESET (RS) WRITE CLOCK (WCLK) READ CLOCK (RCLK) IDT 72421 72201 72211 72221 72231 72241 72251 WRITE ENABLE 1 (WEN1) WRITE ENABLE 2/LOAD (WEN2/LD) DATA IN (D0 - D8) FULL FLAG (FF) PROGRAMMABLE ALMOST-FULL (PAF) READ ENABLE 1 (REN1) OUTPUT ENABLE (OE) DATA OUT (Q0 - Q8) EMPTY FLAG (EF) PROGRAMMABLE ALMOST-EMPTY (PAE) 2655 drw 16 READ ENABLE 2 (REN2) Figure 14. Block Diagram of Single 64 x 9, 256 x 9, 512 x 9, 1,024 x 9, 2,048 x 9, 4,096 x 9, 8,192 x 9 Synchronous FIFO RESET (RS) RESET (RS) DATA IN (D) 18 9 9 READ CLOCK (RCLK) WRITE CLOCK (WCLK) WRITE ENABLE1 (WEN1) WRITE ENABLE2/LOAD (WEN2/LD) FULL FLAG (FF) #1 FULL FLAG (FF) #2 READ ENABLE (REN) IDT 72421 72201 72211 72221 72231 72241 72251 PROGRAMMABLE (PAF) IDT 72421 72201 72211 72221 72231 72241 72251 9 READ ENABLE 2 (REN2) OUTPUT ENABLE (OE) PROGRAMMABLE (PAE) EMPTY FLAG (EF) #1 EMPTY FLAG (EF) #2 9 DATA OUT (Q) READ ENABLE 2 (REN2) Figure 15. Block Diagram of 64 x 18, 256 x 18, 512 x 18, 1,024 x 18, 2,048 x 18, 4,096 x 18, 8,192 x 18 Synchronous FIFO Used in a Width Expansion Configuration 13 18 2655 drw 17 ORDERING INFORMATION IDT XXXXX X XX X Device Type Power Speed Package X Process/ Temperature Range BLANK I(1) Commercial (0C to +70C) Industrial (40 to +85C) J PF Plastic Leaded Chip Carrier (PLCC, J32-1) Thin Quad Flat Pack (TQFP, PR32-1) 10 15 25 Commercial Only Commercial & Industrial Commercial & Industrial L Low Power 72421 72201 72211 72221 72231 72241 72251 64 x 9 SyncFIFO 256 x 9 SyncFIFO 512 x 9 SyncFIFO 1,024 x 9 SyncFIFO 2,048 x 9 SyncFIFO 4,096 x 9 SyncFIFO 8,192 x 9 SyncFIFO Clock Cycle Time (tCLK) Speed in Nanoseconds 2655 drw18 NOTES: 1. Industrial temperature range product for the 15ns and 25ns speed grades are available as standard product. DATASHEET DOCUMENT HISTORY 10/03/2000 05/01/2001 pgs. 2, 3, 4 and 14. pgs. 1, 2, 3, 4 and 14. CORPORATE HEADQUARTERS 2975 Stender Way Santa Clara, CA 95054 for SALES: 800-345-7015 or 408-727-6116 fax: 408-492-8674 www.idt.com* for Tech Support: 408-330-1753 FIFOhelp@idt.com J Pkg: www.idt.com/docs/PSC4013.pdf PF Pkg: www.idt.com/docs/PSC4052.pdf *To search for sales office near you, please click the sales button found on our home page or dial the 800# above and press 2. The SyncFIFO and the IDT logo is a registered trademark of Integrated Device Technology, Inc. 14