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CMOS SyncFIFOTM 64 x 9, 256 x 9, 512 x 9, 1,024 x 9, 2,048 x 9, 4,096 x 9 and 8,192 x 9 FEATURES:
* * * * * * * * * * * * * * * * * *
IDT72421, IDT72201 IDT72211, IDT72221 IDT72231, IDT72241 IDT72251
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
WCLK WEN1 WEN2 D0 - D8 LD
INPUT REGISTER
OFFSET REGISTER EF PAE PAF FF
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
FLAG LOGIC
WRITE POINTER
READ POINTER
READ CONTROL LOGIC
OUTPUT REGISTER RESET LOGIC
RCLK REN1 REN2
RS OE Q0 - Q8
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IDT and the IDT logo are registered trademarks of Integrated Device Technology, Inc. The SyncFIFO is a registered trademark of Integrated Device Technology, Inc.
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
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2002 Integrated Device Technology, Inc. All rights reserved. Product specifications subject to change without notice.
SEPTEMBER 2002
DSC-2655/2
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 and 8,192 x 9
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
PIN CONFIGURATION
RS
D2
D3
D5
D6
D4
D2
D3
D4
D5
D6
D7
INDEX
D8
32 31 30 29 28 27 26 25
4 D1 5 6 7 8 9 10 11 12 13
24 23 22 21 20 19 18 17 WEN1 WCLK WEN2/LD VCC Q8 Q7 Q6 Q5
3
2 1
32 31 30 29 28 27 26 25 24 23 22 21 RS WEN1 WCLK WEN2/LD VCC Q8 Q7 Q6 Q5
D1 D0 PAF PAE GND REN1 RCLK REN2
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
D0 PAF PAE GND REN1 RCLK REN2 OE
14 15 16 17 18 19 20
Q1 Q2 EF Q3 Q4
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OE EF
FF Q0
Q1
Q3
Q2
Q4
FF Q0
D7
D8
INDEX
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TQFP (PR32-1, order code: PF) TOP VIEW
PLCC (J32-1, order code: J) TOP VIEW
PIN DESCRIPTIONS
Symbol Name D0-D8 Data Inputs RS Reset WCLK
WEN1
Write Clock Write Enable 1
WEN2/
LD
Write Enable 2/ Load
Q0-Q8 RCLK
REN1 REN2 OE EF PAE PAF FF
Data Outputs Read Clock Read Enable 1 Read Enable 2 Output Enable Empty Flag Programmable Almost-Empty Flag Programmable Almost-Full Flag Full Flag Power Ground
VCC GND
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.
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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 and 8,192 x 9
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
ABSOLUTE MAXIMUM RATINGS
Symbol VTERM TSTG IOUT Rating Terminal Voltage with Respect to GND Storage Temperature DC Output Current Com'l & Ind'l -0.5 to +7.0 -55 to +125 -50 to +50 Unit V C mA
RECOMMENDED OPERATING CONDITIONS
Symbol VCC GND VIH 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 0 2.0 -- 0 -40 Typ. Max. 5.0 5.5 0 -- -- -- -- 0 -- 0.8 +70 +85 Unit V V V V C C
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.
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. ILI(2) ILO(3) VOH VOL ICC1
(4,5,6)
IDT72251 Com'l and Ind'l(1) tCLK = 10, 15, 25 ns Min. Typ. Max. -1 -10 2.4 -- -- -- -- -- -- -- -- -- 1 10 -- 0.4 50 5
Input Leakage Current (Any Input) Output Leakage Current Output Logic "1" Voltage, IOH = -2mA Output Logic "0" Voltage, IOL = 8mA Active Power Supply Current Standby Current
-1 -10 2.4 -- -- --
-- -- -- -- -- --
1 10 -- 0.4 35 5
ICC2(4,7)
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.
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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 and 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) 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 -- 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 -- 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 --
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
Unit MHz ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns
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.
5V
AC TEST CONDITIONS
In Pulse Levels Input Rise/Fall Times Input Timing Reference Levels Output Reference Levels Output Load GND to 3.0V 3ns 1.5V 1.5V See Figure 1
1.1K D.U.T. 680 30pF*
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
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NOTES: 1. With output deselected (OE VIH). 2. Characterized values, not currently tested.
or equivalent circuit
Figure 1. Output Load
*includes jig and scope capacitances 4
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 and 8,192 x 9
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
SIGNAL DESCRIPTIONS INPUTS:
DATA IN (D0 - D8) Data inputs for 9-bit wide data.
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. 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
WCLK
0
0
Selection Empty Offset (LSB) Empty Offset (MSB) Full Offset (LSB) Full Offset (MSB) No Operation Write Into FIFO No Operation
0 1 1
1 0 1
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
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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 and 8,192 x 9
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
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).
A read and write should not be performed simultaneously to the offset registers.
IDT72421 - 64 x 9-BIT
8 65 0 Empty Offset (LSB) Reg. Default Value 007H 8 0 8 8
IDT72201 - 256 x 9-BIT
7 Empty Offset (LSB) Reg. Default Value 007H 0 0
8
65 Full Offset (LSB) Reg. Default Value 007H
0
8
7 Full Offset (LSB) Reg. Default Value 007H
0
8
0
8
0
IDT72211 - 512 x 9-BIT
8 7 Empty Offset (LSB) Default Value 007H 8 1 (MSB) 0 8 7 Full Offset (LSB) Default Value 007H 8 1 (MSB) 0 0 8 0 8 0 8 0 8
IDT72221 - 1,024 x 9-BIT
7 Empty Offset (LSB) Reg. Default Value 007H 1 (MSB) 00 7 Full Offset (LSB) Reg. Default Value 007H 1 (MSB) 00 0 0 0 0
IDT72231 - 2,048 x 9-BIT
8 7 Empty Offset (LSB) Reg. Default Value 007H 8 2 (MSB) 000 8 7 Full Offset (LSB) Reg. Default Value 007H 8 2 (MSB) 000 0 8 0 8 0 8 0 8
IDT72241 - 4,096 x 9-BIT
7 Empty Offset (LSB) Default Value 007H 3 (MSB) 0000 7 Full Offset (LSB) Default Value 007H 3 (MSB) 0000 0 8 0 8 0 8 0 8
IDT72251 8,192 x 9-BIT
7 Empty Offset (LSB) Default Value 007H 4 (MSB) 00000 7 Full Offset (LSB) Default Value 007H 4 (MSB) 00000
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0
0
0
0
Figure 3. Offset Register Location and Default Values
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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 and 8,192 x 9
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
OUTPUTS:
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). 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,
(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). 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). DATA OUTPUTS (Q0 - Q8) Data outputs for a 9-bit wide data.
TABLE 1 -- STATUS FLAGS
IDT72421 0 1 to n (1) (n+1) to (64-(m+1)) (64-m)(2) to 63 64 NUMBER OF WORDS IN FIFO IDT72201 0 1 to n (1) (n+1) to (256-(m+1)) (256-m)(2) to 255 256 IDT72211 0 1 to n (1) (n+1) to (512-(m+1)) (512-m)(2) to 511 512 FF H H H H L PAF H H H L L PAE L L H H H EF L H H H H
NUMBER OF WORDS IN FIFO IDT72221 0 1 to n
(1)
IDT72231 0 1 to n
(1)
IDT72241 0 1 to n
(1)
IDT72251 0 1 to n
(1)
FF H H H H L
PAF H H H L L
PAE L L H H H
EF L H H H H
(n+1) to (1,024-(m+1)) (1,024-m) to 1,023 1,024
(2)
(n+1) to (2,048-(m+1)) (2,048-m) to 2,047 2,048
(2)
(n+1) to (4,096-(m+1)) (4,096-m) to 4,095 4,096
(2)
(n+1) to (8,192-(m+1)) (8,192-m) to 8,191 8,192
(2)
NOTES: 1. n = Empty Offset (n = 7 default value) 2. m = Full Offset (m = 7 default value)
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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 and 8,192 x 9
tRS RS tRSS REN1, REN2 tRSS WEN1 tRSS WEN2/LD (1) tRSF EF, PAE tRSF FF, PAF tRSF Q0 - Q8 tRSR tRSR tRSR
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
OE = 1
(2)
OE = 0
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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 WCLK tDH tDS D0 - D8 DATA IN VALID tENS WEN1 tENS WEN2/ (If Applicable) tWFF FF tSKEW1(1) RCLK REN1, REN2 tWFF tENH NO OPERATION tENH NO OPERATION tCLKL
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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
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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 and 8,192 x 9
tCLK tCLKH RCLK tENS REN1, REN2 tREF EF tA Q0 - Q8 tOLZ tOE OE WCLK VALID DATA tOHZ tSKEW1
(1)
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
tCLKL
tENH NO OPERATION tREF
WEN1
WEN2
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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 tENS WEN1 tENS WEN2 (If Applicable) tSKEW1 RCLK tREF EF REN1, REN2 tENS tFRL
(1)
D1 D0 (First Valid Write)
D2
D3
tA Q0 - Q8 tOLZ 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).
tA D0 D1
tOE
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Figure 7. First Data Word Latency Timing
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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 and 8,192 x 9
NO WRITE WCLK tSKEW1 D0 - D8 tWFF FF tENS WEN1 tENS WEN2 (If Applicable) tENH tENH tWFF tDS NO WRITE
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
NO WRITE
tSKEW1
tWFF tENS
(1)
tENS
(1)
RCLK tENS tENH tENS tENH
REN1, REN2 OE LOW
tA tA
Q0 - Q8 DATA IN OUTPUT REGISTER
DATA READ
NEXT DATA READ
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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 tENS WEN1 tENS WEN2 (If Applicable) tSKEW1 RCLK tREF EF REN1, REN2 OE LOW tA Q0 - Q8 DATA IN OUTPUT REGISTER
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).
tDS DATA WRITE 1 tENH tENS DATA WRITE 2 tENH
tENH
tENS
tENH
tFRL
(1)
tSKEW1
tFFL
(1)
tREF
tREF
DATA READ
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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 and 8,192 x 9
tCLKH WCLK tENS WEN1 tENS WEN2 (If Applicable) tPAF PAF Full - (m+1) words in FIFO
(1)
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
tCLKL
(4)
tENH
tENH
Full - m words in FIFO tSKEW2
(2)
(3)
tPAF
RCLK tENS REN1, REN2 tENH
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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 WCLK
tCLKL
tENS WEN1 tENS WEN2 (If Applicable)
tENH
tENH
PAE
n words in FIFO (1) tSKEW2 (2) tPAE
n+1 words in FIFO tPAE
(3)
RCLK tENS REN1, REN2 tENH
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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
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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 and 8,192 x 9
tCLK tCLKH WCLK tENS LD tENS WEN1 tDS D0 - D7 PAE OFFSET (LSB) PAE OFFSET (MSB) PAF OFFSET (LSB) tDH tENH tCLKL
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
PAF OFFSET (MSB)
2655 drw 14
Figure 12. Write Offset Registers Timing
tCLK tCLKH RCLK tENS LD tENS REN1, REN2 tA Q0 - Q7 DATA IN OUTPUT REGISTER EMPTY OFFSET (LSB) EMPTY OFFSET (MSB) FULL OFFSET (LSB) FULL OFFSET (MSB)
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tCLKL
tENH
Figure 13. Read Offset Registers Timing
12
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 and 8,192 x 9
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
OPERATING CONFIGURATIONS
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. 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
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.
RESET (RS) WRITE CLOCK (WCLK) WRITE ENABLE 1 (WEN1) WRITE ENABLE 2/LOAD (WEN2/LD) DATA IN (D0 - D8) FULL FLAG (FF) PROGRAMMABLE ALMOST-FULL (PAF) IDT 72421 72201 72211 72221 72231 72241 72251 READ CLOCK (RCLK) READ ENABLE 1 (REN1) OUTPUT ENABLE (OE) DATA OUT (Q0 - Q8) EMPTY FLAG (EF) PROGRAMMABLE ALMOST-EMPTY (PAE)
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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) DATA IN (D) 18 9 9
RESET (RS)
READ CLOCK (RCLK) WRITE CLOCK (WCLK) WRITE ENABLE1 (WEN1) WRITE ENABLE2/LOAD (WEN2/LD) FULL FLAG (FF) #1 FULL FLAG (FF) #2 PROGRAMMABLE (PAF)
IDT 72421 72201 72211 72221 72231 72241 72251 IDT 72421 72201 72211 72221 72231 72241 72251
READ ENABLE (REN) OUTPUT ENABLE (OE) PROGRAMMABLE (PAE) EMPTY FLAG (EF) #1 EMPTY FLAG (EF) #2 9 DATA OUT (Q)
9
18
READ ENABLE 2 (REN2)
READ ENABLE 2 (REN2)
2655 drw 17
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
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ORDERING INFORMATION
IDT XXXXX X XX X Device Type Power Speed Package X Process/ Temperature Range BLANK I(1) J PF 10 15 25 Commercial (0C to +70C) Industrial (40 to +85C) Plastic Leaded Chip Carrier (PLCC, J32-1) Thin Quad Flat Pack (TQFP, PR32-1) Commercial Only Commercial & Industrial Commercial & Industrial Low Power 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
L 72421 72201 72211 72221 72231 72241 72251
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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
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for Tech Support: 408-330-1753 FIFOhelp@idt.com

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