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DUAL CMOS SyncFIFOTM
DUAL 256 x 9, DUAL 512 x 9, DUAL 1,024 x 9, DUAL 2,048 x 9, DUAL 4,096 x 9, DUAL 8,192 x 9
IDT72801 IDT72811 IDT72821 IDT72831 IDT72841 IDT72851
.EATURES:
* * * * * * * * * * * * * * *
The IDT72801 is equivalent to two IDT72201 256 x 9 FIFOs The IDT72811 is equivalent to two IDT72211 512 x 9 FIFOs The IDT72821 is equivalent to two IDT72221 1,024 x 9 FIFOs The IDT72831 is equivalent to two IDT72231 2,048 x 9 FIFOs The IDT72841 is equivalent to two IDT72241 4,096 x 9 FIFOs The IDT72851 is equivalent to two IDT72251 8,192 x 9 FIFOs Offers optimal combination of large capacity, high speed, design flexibility and small footprint Ideal for prioritization, bidirectional, and width expansion applications 10 ns read/write cycle time for the IDT72801/72811/72821/72831/ 72841 (excluding the IDT72851) 15 ns read/write cycle time for the IDT72851 Separate control lines and data lines for each FIFO Separate Empty, Full, Programmable Almost-Empty and AlmostFull flags for each FIFO Enable puts output data lines in high-impedance state Space-saving 64-pin Thin Quad Flat Pack (TQFP) and Slim Thin Quad Flatpack (STQFP) Industrial temperature range (-40C to +85C) is available
DESCRIPTION:
The IDT72801/72811/72821/72831/72841/72851 are dual synchronous (clocked) FIFOs. The device is functionally equivalent to two IDT72201/72211/ 72221/72231/72241/72251 FIFOs in a single package with all associated control, data, and flag lines assigned to separate pins.
Each of the two FIFOs (designated FIFO A and FIFO B) contained in the IDT72801/72811/72821/72831/72841/72851 has a 9-bit input data port (DA0 - DA8, DB0 - DB8) and a 9-bit output data port (QA0 - QA8, QB0 - QB8). Each input port is controlled by a free-running clock (WCLKA, WCLKB), and two Write Enable pins (WENA1, WENA2, WENB1, WENB2). Data is written into each of the two arrays on every rising clock edge of the Write Clock (WCLKA, WCLKB) when the appropriate write enable pins are asserted. The output port of each FIFO bank is controlled by its associated clock pin (RCLKA, RCLKB) and two Read Enable pins (RENA1, RENA2, RENB1, RENB2). 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 (OEA, OEB) is provided on the read port of each FIFO for three-state output control. Each of the two FIFOs has two fixed flags, Empty (EFA, EFB) and Full (FFA, FFB). Two programmable flags, Almost-Empty (PAEA, PAEB) and Almost-Full (PAFA, PAFB), are provided for each FIFO bank to improve memory utilization. If not programmed, the programmable flags default to empty+7 for PAEA and PAEB, and full-7 for PAFA and PAFB. The IDT72801/72811/72821/72831/72841/72851 architecture lends itself to many flexible configurations such as: * 2-level priority data buffering * Bidirectional operation * Width expansion * Depth expansion These FIFOs is fabricated using IDT's high-performance submicron CMOS technology.
.UNCTIONAL BLOCK DIAGRAM
WCLKA WENA1 WENA2 DA0 - DA8 EFA PAEA PAFA LDA FFA WCLKB WENB1 WENB2 DB0 - DB8 LDB
INPUT REGISTER
OFFSET REGISTER FLAG LOGIC
INPUT REGISTER
OFFSET REGISTER EFB PAEB PAFB FFB
WRITE CONTROL LOGIC RAM ARRAY 256 x 9, 512 x 9, 1024 x 9, 2048 x 9, 4096 x 9, 8192 x 9
WRITE CONTROL LOGIC RAM ARRAY 256 x 9, 512 x 9, 1024 x 9, 2048 x 9, 4096 x 9, 8192 x 9
FLAG LOGIC
WRITE POINTER
READ POINTER
WRITE POINTER
READ POINTER
READ CONTROL LOGIC
READ CONTROL LOGIC
OUTPUT REGISTER RESET LOGIC RESET LOGIC
OUTPUT REGISTER
RSA
OEA
QA0 - QA8
RCLKA RENA1 RENA2
RSB
OEB
QB0 - QB8
RCLKB RENB1 RENB2
3034 drw 01
SyncFIFO is a trademark and the IDT logo is a registered trademark of Integrated Device Technology, Inc.
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGE
2001 Integrated Device Technology, Inc.
APRIL 2001
DSC-3034/1
IDT72801/728211/72821/72831/72841/72851
Commercial And Industrial Temperature Range
PIN CON.IGURATION
QA0 FFA EFA OEA RENA2 RCLKA RENA1 GND QB8 QB7 QB6 QB5 QB4 QB3 QB2 QB1 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49
48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33
DA5 DA4 DA3 DA2 DA1 DA0 PAFA PAEA WENB2/LDB WCLKB WENB1 RSB DB8 DB7 DB6 DB5
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
QA1 QA2 QA3 QA4 QA5 QA6 QA7 QA8 VCC WENA2/LDA WCLKA WENA1 RSA DA8 DA7 DA6
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
QB0 FFB EFB OEB RENB2 RCLKB RENB1 GND VCC PAEB PAFB DB0 DB1 DB2 DB3 DB4
3034 drw 02
TQFP (PN64-1, order code: PF) STQFP (PP64-1, order code: TF) TOP VIEW
2
IDT72801/728211/72821/72831/72841/72851
Commercial And Industrial Temperature Range
PIN DESCRIPTIONS
The IDT72801/72811/72821/72831/72841/72851s two FIFOs, referred to as FIFO A and FIFO B, are identical in every respect. The following Symbol DA0-DA8 DB0-DB8
RSA, RSB
description defines the input and output signals for FIFO A. The corresponding signal names for FIFO B are provided in parentheses. Description
Name A Data Inputs B Data Inputs Reset
I/O I I I
9-bit data inputs to RAM array A. 9-bit data inputs to RAM array B. When RSA (RSB) is set LOW, the associated internal read and write pointers of array A (B) are set to the first location; FFA (FFB) and PAFA (PAFB) go HIGH, and PAEA (PAEB) and EFA (EFB) go LOW. After power-up, a reset of both FIFOs A and B is required before an initial Write. Data is written into the FIFO A (B) on a LOW-to-HIGH transition of WCLKA (WCLKB) when the write enable(s) are asserted. If FIFO A (B) is configured to have programmable flags, WENA1 (WENB1) is the only Write Enable pin that can be used. When WENA1 (WENB1) is LOW, data A (B) is written into the FIFO on every LOW-to-HIGH transition WCLKA (WCLKB). If the FIFO is configured to have two write enables, WENA1 (WENB1) must be LOW and WENA2 (WENB2) must be HIGH to write data into the FIFO. Data will not be written into the FIFO if FFA (FFB) is LOW. FIFO A (B) is configured at reset to have either two write enables or programmable flags. If LDA (LDB) is HIGH at reset, this pin operates as a second write enable. If WENA2/LDA (WENB2/LDB) is LOW at reset this pin operates as a control to load and read the programmable flag offsets for its respective array. If the FIFO is configured to have two write enables, WENA1 (WENB1) must be LOW and WENA2 (WENB2) must be HIGH to write data into FIFO A (B). Data will not be written into FIFO A (B) if FFA (FFB) is LOW. If the FIFO is configured to have programmable flags, LDA (LDB) is held LOW to write or read the programmable flag offsets. 9-bit data outputs from RAM array A. 9-bit data outputs from RAM array B. Data is read from FIFO A (B) on a LOW-to-HIGH transition of RCLKA (RCLKB) when RENA1 (RENB1) and RENA2 (RENB2) are asserted. When RENA1 (RENB1) and RENA2 (RENB2) are LOW, data is read from FIFO A (B) on every LOW-to-HIGH transition of RCLKA (RCLKB). Data will not be read from Array A (B) if EFA (EFB) is LOW. When RENA1 (RENB1) and RENA2 (RENB2) are LOW, data is read from the FIFO A (B) on every LOW-to-HIGH transition of RCLKA (RCLKB). Data will not be read from array A (B) if the EFA (EFB) is LOW. When OEA (OEB) is LOW, outputs DA0-DA8 (DB0-DB8) are active. If OEA (OEB) is HIGH, the outputs DA0-DA8 (DB0-DB8) will be in a high-impedance state. When EFA (EFB) is LOW, FIFO A (B) is empty and further data reads from the output are inhibited. When EFA (EFB) is HIGH, FIFO A (B) is not empty. EFA (EFB) is synchronized to RCLKA (RCLKB). When PAEA (PAEB) is LOW, FIFO A (B) is almost-empty based on the offset programmed into the appropriate offset register. The default offset at reset is Empty+7. PAEA (PAEB) is synchronized to RCLKA (RCLKB). When PAFA (PAFB) is LOW, FIFO A (B) is almost-full based on the offset programmed into the appropriate offset register. The default offset at reset is Full-7. PAFA (PAFB) is synchronized to WCLKA (WCLKB). When FFA (FFB) is LOW, FIFO A (B) is full and further data writes into the input are inhibited. When FFA (FFB) is HIGH, FIFO A (B) is not full. FFA (FFB) is synchronized to WCLKA (WCLKB). +5V power supply pin. 0V ground pin.
WCLKA WCLKB
WENA1 WENB1
Write Clock Write Enable 1
I I
WENA2/LDA WENB2/LDB
Write Enable 2/ Load
I
QA0-QA8 QB0-QB8 RCLKA RCLKB
RENA1 RENB1 RENA2 RENB2 OEA OEB EFA EFB PAEA PAEB PAFA PAFB FFA FFB
A Data Outputs B 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
O O I I I I O O
O O
VCC GND
3
IDT72801/728211/72821/72831/72841/72851
Commercial And Industrial Temperature Range
ABSOLUTE MAXIMUM RATINGS
Symbol VTERM TSTG IOUT Rating Com'l & Ind'l Unit
RECOMMENDEDOPERATINGCONDITIONS
Symbol Parameter Min. Typ. Max. Unit
Terminal Voltage with Respect to GND
StorageTemperature DC Output Current
-0.5 to +7.0
-55 to +125 -50 to +50
V C
mA
VCC GND VIH VIL TA TA
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.
Supply Voltage (Com'l & Ind'l) Supply Voltage (Com'l & Ind'l) Input High Voltage (Com'l & Ind'l) Input Low Voltage (Com'l & Ind'l) Operating Temperature Commercial Operating Temperature Industrial
4.5 0 2.0 -- 0 -40
5.0 0 -- -- -- --
5.5 0 --
V V V
0.8 V 70 C 85 C
DC ELECTRICAL CHARACTERISTICS
(Commercial: VCC = 5V 10%, TA = 0C to +70C; Industrial: VCC = 5V 10%, TA = -40C to +85C)
IDT72801 IDT72811 IDT72821 IDT72831 IDT72841 Commercial and Industrial(1) tCLK = 10, 15, 25 ns
IDT72851 Commercial and Industrial(1) tCLK = 10, 15, 25 ns
Symbol
ILI
(2)
Parameter
Input Leakage Current (Any Input) Output Leakage Current Output Logic "1" Voltage, IOH = -2 mA Output Logic "0" Voltage, IOL = 8 mA Active Power Supply Current (both FIFOs) Standby Current
Min.
-1 -10 2.4 -- -- --
Typ.
-- -- -- -- -- --
Max.
1 10 -- 0.4 60 10
Min.
-1 -10 2.4 -- -- --
Typ.
-- -- -- -- -- --
Max.
1 10 -- 0.4 80 10
Unit
A A V V mA mA
ILO(3) VOH VOL ICC1(4,5,6,8) ICC2
(4,7,8)
NOTES: 1. Industrial temperature range product for 15ns and 25ns speed grade are available as a standard device. 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 = 2*[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. 8. ICC1 and ICC2 parameters are improved as compared to previous data sheets.
CAPACITANCE (TA = +25C, f = 1.0MHz)
Symbol CIN
(2) (1,2)
Parameter Input Capacitance Output Capacitance
Conditions VIN = 0V VOUT = 0V
Max. 10 10
Unit pF pF
COUT
NOTE:
1. With output deselected (OEA, OEB VIH). 2. Characterized values, not currently tested.
4
IDT72801/728211/72821/72831/72841/72851
Commercial And Industrial Temperature Range
AC ELECTRICAL CHARACTERISTICS
(Commercial: VCC = 5V 10%, TA = 0C to +70C; Industrial: VCC = 5V 10%, TA = -40C to +85C)
Com'l & Commercial IDT72801L10 IDT72811L10 IDT72821L10 IDT72831L10 IDT72841L10 IDT72851L10 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)
Ind'l (1) IDT72801L15 IDT72811L15 IDT72821L15 IDT72831L15 IDT72841L15 IDT72851L15 Min -- 2 15 6 6 4 1 4 1 15 10 10 -- 0 3 3 -- -- -- -- 6 15 Max. 66.7 10 -- -- -- -- -- -- -- -- -- -- 15 -- 8 8 10 10 10 10 -- -- IDT72801L25 IDT72811L25 IDT72821L25 IDT72831L25 IDT72841L25 IDT72851L25 Min -- 2 25 10 10 6 1 6 1 15 15 15 -- 0 3 3 -- -- -- -- 10 18 Max. 40 15 -- -- -- -- -- -- -- -- -- -- 25 -- 13 13 15 15 15 15 -- -- Unit MHz ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns
Min -- 2 10 4.5 4.5 3 0.5 3 0.5 10 8 8 -- 0 3 3 -- -- -- -- 5 14
Max. 100 6.5 -- -- -- -- -- -- -- -- -- -- 10 -- 6 6 6.5 6.5 6.5 6.5 -- --
Reset Setup Time Reset Recovery Time Reset to Flag Time 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 and Write Clock for Empty Flag and Full Flag Skew Time Between Read Clock and Write Clock for Programmable Almost-Empty Flag and Programmable Almost-Full Flag
NOTES: 1. Industrial temperature range product for 15ns and 25ns speed grade are available as a standard device. 2. Pulse widths less than minimum values are not allowed. 3. Values guaranteed by design, not currently tested.
5V 1.1K
AC TEST CONDITIONS
In Pulse Levels GND to 3.0V
D.U.T. 680 30pF*
Input Rise/Fall Times Input Timing Reference Levels Output Reference Levels Output Load
3ns 1.5V 1.5V See Figure 1 or equivalent circuit
3034 drw 03
Figure 1. Output Load
*Includes jig and scope capacitances. 5
IDT72801/728211/72821/72831/72841/72851
Commercial And Industrial Temperature Range
When either of the two Read Enable RENA1, RENA2 (RENB1, RENB2) associated with FIFO A (B) 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 FIFO A (B), the Empty Flag EFA (EFB) will go LOW, inhibiting further read operations. Once a valid write operation has been accomplished, EFA (EFB) will go HIGH after tREF and a valid read can begin. The Read Enables RENA1, RENA2(RENB1, RENB2) are ignored when FIFO A (B) is empty. Output Enable (OEA, OEB) -- When Output Enable OEA (OEB) is enabled (LOW), the parallel output buffers of FIFO A (B) receive data from their respective output register. When Output Enable OEA (OEB) is disabled (HIGH), the QA (QB) output data bus is in a high-impedance state. Write Enable 2/Load (WENA2/LDA, WENB2/LDB) -- This is a dualpurpose pin. FIFO A (B) is configured at Reset to have programmable flags or to have two write enables, which allows depth expansion. If WENA2/LDA (WENB2/LDB) is set HIGH at Reset RSA = LOW (RSB = LOW), this pin operates as a second write enable pin. If FIFO A (B) is configured to have two write enables, when Write Enable 1 WENA1 (WENB1) is LOW and WENA2/LDA (WENB2/LDB) is HIGH, data can be loaded into the input register and RAM array on the LOW-to-HIGH transition of every Write Clock WCLKA (WCLKB). Data is stored in the array sequentially and independently of any ongoing read operation. In this configuration, when WENA1 (WENB1) is HIGH and/or WENA2/LDA (WENB2/LDB) is LOW, the input register of Array A holds the previous data and no new data is allowed to be loaded into the register. To prevent data overflow, the Full Flag FFA (FFB) will go LOW, inhibiting further write operations. Upon the completion of a valid read cycle, FFA (FFB) will go HIGH after tWFF, allowing a valid write to begin. WENA1, (WENB1) and WENA2/LDA (WENB2/LDB) are ignored when the FIFO is full. FIFO A (B) is configured to have programmable flags when the WENA2/ LDA (WENB2/LDB) is set LOW at Reset RSA = LOW (RSB = LOW). Each FIFO contains 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 FIFO A (B) is configured to have programmable flags, when the WENA1 (WENB1) and WENA2/LDA (WENB2/LDB) are set LOW, data on the DA (DB) inputs are written into the Empty (Least Significant Bit) Offset register on the first LOW-to-HIGH transition of the WCLKA (WCLKB). Data are written into the Empty (Most Significant Bit) Offset register on the second LOW-to-HIGH transition of WCLKA (WCLKB), 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 WCLKA (WCLKB) 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 LDA (LDB) HIGH, FIFO A (B) is returned to normal read/write operation. When LDA (LDB) is set LOW, and WENA1 (WENB1) is LOW, the next offset register in sequence is written. The contents of the offset registers can be read on the QA (QB) outputs when WENA2/LDA (WENB2/LDB) is set LOW and both Read Enables RENA1, RENA2 (RENB1, RENB2) are set LOW. Data can be read on the LOW-to-HIGH transition of the Read Clock RCLKA (RCLKB).
SIGNAL DESCRIPTIONS
FIFO A and FIFO B are identical in every respect. The following description explains the interaction of input and output signals for FIFO A. The corresponding signal names for FIFO B are provided in parentheses.
INPUTS:
Data In (DA0 - DA8, DB0 - DB8) --DA0 - DA8 are the nine data inputs for memory array A. DB0 - DB8 are the nine data inputs for memory array B.
CONTROLS: Reset (RSA, RSB) -- Reset of FIFO A (B) is accomplished whenever RSA
(RSB) input is taken to a LOW state. During Reset, the internal read and write pointers associated with the FIFO are set to the first location. A Reset is required after power-up before a write operation can take place. The Full Flag FFA (FFB) and Programmable Almost-Full flag PAFA (PAFB) will be reset to HIGH after tRSF. The Empty Flag EFA (EFB) and Programmable Almost-Empty flag PAEA (PAEB) 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 (WCLKA, WCLKB) -- A write cycle to Array A (B) is initiated on the LOW-to-HIGH transition of WCLKA (WCLKB). Data setup and hold times must be met with respect to the LOW-to-HIGH transition of WCLKA (WCLKB). The Full Flag FFA (FFB) and Programmable Almost-Full flag PAFA (PAFB) are synchronized with respect to the LOW-to-HIGH transition of the Write Clock WCLKA (WCLKB). The Write and Read Clocks can be asynchronous or coincident. Write Enable 1 (WENA1, WENB1) -- If FIFO A (B) is configured for programmable flags, WENA1 (WENB1) is the only enable control pin. In this configuration, when WENA1 (WENB1) is LOW, data can be loaded into the input register of RAM Array A (B) on the LOW-to-HIGH transition of every Write Clock WCLKA (WCLKB). Data is stored in Array A (B) sequentially and independently of any ongoing read operation. In this configuration, when WENA1 (WENB1) 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. See Write Enable 2 paragraph below for operation in this configuration. To prevent data overflow, FFA (FFB) will go LOW, inhibiting further write operations. Upon the completion of a valid read cycle, the FFA (FFB) will go HIGH after tWFF, allowing a valid write to begin. WENA1 (WENB1) is ignored when FIFO A (B) is full. Read Clock (RCLKA, RCLKB) -- Data can be read from Array A (B) on the LOW-to-HIGH transition of RCLKA (RCLKB). The Empty Flag EFA (EFB) and Programmable Almost-Empty Flag PAEA (PAEB) are synchronized with respect to the LOW-to-HIGH transition of RCLKA (RCLKB). The Write and Read Clocks can be asynchronous or coincident. Read Enables (RENA1, RENA2, RENB1, RENB2) -- When both Read Enables RENA1, RENA2 (RENB1, RENB2) are LOW, data is read from Array A (B) to the output register on the LOW-to-HIGH transition of the Read Clock RCLKA (RCLKB).
6
IDT72801/728211/72821/72831/72841/72851
LDA LDB 0 WENA1 WENB1 0 WCLKA WCLKB OPERATION ON FIFO A OPERATION ON FIFO B Empty Offset (LSB) Empty Offset (MSB) Full Offset (LSB) Full Offset (MSB) 0 1 1 1 0 1 No Operation Write Into FIFO No Operation
Commercial And Industrial Temperature Range
A read and write should not be performed simultaneously to the offset registers.
OUTPUTS:
Full Flag (FFA, FFB) -- FFA (FFB) will go LOW, inhibiting further write operations, when Array A (B) is full. If no reads are performed after reset, FFA (FFB) will go LOW after 256 writes to the IDT72801's FIFO A (B); 512 writes to the IDT72811's FIFO A (B); 1,024 writes to the IDT72821's FIFO A (B); 2,048 writes to the IDT72831's FIFO A (B); 4,096 writes to the IDT72841's FIFO A (B); or 8,192 writes to the IDT72851's FIFO A (B). FFA (FFB) is synchronized with respect to the LOW-to-HIGH transition of the Write Clock WCLKA (WCLKB).
NOTE: 1. For the purposes of this table, WENA1 and WENB1 = VIH. 2. The same selection sequence applies to reading from the registers. RENA1 and RENA2 (RENB1 and RENB2) are enabled and read is performed on the LOW-toHIGH transition of RCLKA (RCLKB).
Empty Flag (EFA, EFB) -- EFA (EFB) will go LOW, inhibiting further read operations, when the read pointer is equal to the write pointer, indicating that Array A (B) is empty. EFA (EFB) is synchronized with respect to the LOW-to-HIGH transition of the Read Clock RCLKA (RCLKB).
Figure 2. Writing to Offset Registers for FIFOs A and B
72801 - DUAL 256 x 9 8 7 Empty Offset (LSB) Reg. Default Value 007H 8 0 8 0 8 7
72811 - DUAL 512 x 9 0 Empty Offset (LSB) Default Value 007H 1 (MSB) 0 0 8 8 7
72821 - DUAL 1,024 x 9 0 Empty Offset (LSB) Default Value 007H 1 (MSB) 0 0 8 7 Full Offset (LSB) Reg. Default Value 007H 0 (MSB) 0 8 1 (MSB) 0 0 0 0
8
7 Full Offset (LSB) Reg. Default Value 007H
0
8
7 Full Offset (LSB) Default Value 007H
8
0
8
1
72831 - DUAL 2,048 x 9 8 7 Empty Offset (LSB) Reg. Default Value 007H 8 2 (MSB) 0 8 7 Full Offset (LSB) Reg. Default Value 007H 8 2 (MSB) 0 0 8 0 8 7 0 8 0 8 7
72841 - DUAL 4,096 x 9 0 Empty Offset (LSB) Default Value 007H 3 (MSB) 0 0 Full Offset (LSB) Default Value 007H 3 (MSB) 0 0 8 8 7 0 8 8 7
72851 - DUAL 8,192 x 9 0 Empty Offset (LSB) Default Value 007H 4 (MSB) 0 0 Full Offset (LSB) Default Value 007H 4 (MSB) 0
3034 drw 04
0
0
Figure 3. Offset Register Formats and Default Values for the A and B FIFOs
7
IDT72801/728211/72821/72831/72841/72851
Programmable Almost-Full Flag (PAFA, PAFB) -- PAFA (PAFB) will go LOW when the amount of data in Array A (B) reaches the almost-full condition. If no reads are performed after Reset, PAFA (PAFB) will go LOW after (256-m) writes to the IDT72801's FIFO A (B); (512-m) writes to the IDT72811's FIFO A (B); (1,024-m) writes to the IDT72821's FIFO A (B); (2,048-m) writes to the IDT72831's FIFO A (B); (4,096-m) writes to the IDT72841's FIFO A (B); or (8,192-m) writes to the IDT72851's FIFO A (B). FFA (FFB) is synchronized with respect to the LOW-to-HIGH transition of the Write Clock WCLKA (WCLKB). The offset "m" is defined in the Full Offset registers. If there is no Full offset specified, PAFA (PAFB) will go LOW at Full-7 words. PAFA (PAFB) is synchronized with respect to the LOW-to-HIGH transition of WCLKA (WCLKB).
Commercial And Industrial Temperature Range
Programmable Almost-Empty Flag (PAEA, PAEB) -- PAEA (PAEB) 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, PAEA (PAEB) will go HIGH after "n+1" writes to FIFO A (B). If there is no Empty offset specified, PAEA (PAEB) will go LOW at Empty+7 words. PAEA (PAEB) is synchronized with respect to the LOW-to-HIGH transition of the Read Clock RCLKA (RCLKB). Data Outputs (QA0 - QA8, QB0 - QB8 ) -- QA0 - QA8 are the nine data outputs for memory array A, QB0 - QB8 are the nine data outputs for memory array B.
TABLE 1: STATUS .LAGS .OR A AND B .I.OS
NUMBER OF WORDS IN ARRAY A NUMBER OF WORDS IN ARRAY B 72801 0 1 to n(1) (n+1) to (256-(m+1)) (256-m)(2) to 255 256 72811 0 1 to n(1) (n+1) to (512-(m+1)) (512-m)(2) to 511 512 72821 0 1 to n(1) (n+1) to (1,024-(m+1)) (1,024-m)(2) to 1,023 1,024
FFA FFB PAFA PAFB PAEA PAEB EFA EFB
H H H H L
H H H L L
L L H H H
L H H H H
NUMBER OF WORDS IN ARRAY A NUMBER OF WORDS IN ARRAY B 72831 0 1 to n(1) (n+1) to (2,048-(m+1)) (2,048-m)(2) to 2,047 2,048 72841 0 1 to n(1) (n+1) to (4,096-(m+1)) (4,096-m)(2) to 4,095 4,096 72851 0 1 to n(1) (n+1) to (8,192-(m+1)) (8,192-m)(2) to 8,191 8,192
FFA FFB
PAFA PAFB
PAEA PAEB
EFA EFB
H H H H L
H H H L L
L L H H H
L H H H H
NOTES: 1. n = Empty Offset (n = 7 default value) 2. m = Full Offset (m = 7 default value)
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IDT72801/728211/72821/72831/72841/72851
tRS RSA (RSB) tRSS RENA1, RENA2 (RENB1, RENB2) tRSS WENA1 (WENB1) tRSS WENA2/LDA(1) (WENB2/LDB) tRSF EFA, PAEA (EFB, PAEB) tRSF FFA, PAFA (FFB, PAFB) tRSF QA0 - QA8 (QB0 - QB8)
Commercial And Industrial Temperature Range
tRSR
tRSR
tRSR
OEA (OEB) = 1
(2)
OEA (OEB) = 0
NOTES: 1. Holding WENA2/LDA (WENB2/LDB) HIGH during reset will make the pin act as a second write enable pin. Holding WENA2/LDA (WENB2/LDB) LOW during reset will make the pin act as a load enable for the programmable flag offset registers. 2. After reset, QA0 - QA8 (QB0 - QB8) will be LOW if OEA (OEB) = 0 and tri-state if OEA (OEB) = 1. 3. The clocks RCLKA, WCLKA (RCLKB, WCLKB) can be free-running during reset.
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Figure 4. Reset Timing
tCLK tCLKH WCLKA (WCLKB) tDS DA0 - DA8 (DB0 - DB8) DATA IN VALID WENA1 (WENB1) WENA2 (WENB2) (If Applicable) tWFF FFA (FFB) tSKEW1(1) RCLKA (RCLKB) tWFF tENS tENH NO OPERATION tENS tENH NO OPERATION tDH tCLKL
RENA1, RENA2 (RENB1, RENB2)
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NOTE: 1. tSKEW1 is the minimum time between a rising RCLKA (RCLKB) edge and a rising WCLKA (WCLKB) edge for FFA (FFB) to change during the current clock cycle. If the time between the rising edge of RCLKA (RCLKB) and the rising edge of WCLKA (WCLKB) is less than tSKEW1, then FFA (FFB) may not change state until the next WCLKA (WCLKB) edge.
Figure 5. Write Cycle Timing
9
IDT72801/728211/72821/72831/72841/72851
tCLK tCLKH RCLKA (RCLKB) tENS RENA1, RENA2 (RENB1, RENB2) tREF EFA (EFB) tA QA0 - QA8 (QB0 - QB8) tOLZ tOE OEA (OEB) tSKEW1(1) WCLKA (WCLKB) tENH tCLKL
Commercial And Industrial Temperature Range
NO OPERATION tREF
VALID DATA tOHZ
WENA1 (WENB1)
WENA2 (WENB2)
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NOTE: 1. tSKEW1 is the minimum time between a rising WCLKA (WCLKB) edge and a rising RCLKA (RCLKB) edge for EFA (EFB) to change during the current clock cycle. If the time between the rising edge of RCLKA (RCLKB) and the rising edge of WCLKA (WCLKB) is less than tSKEW1, then EFA (EFB) may not change state until the next RCLKA (RCLKB)
Figure 6. Read Cycle Timing
WCLKA (WCLKB) tDS DA0 - DA8 (DB0 - DB8) tENS WENA1 (WENB1) tENS WENA2 (WENB2) (If Applicable) tSKEW1 RCLKA (RCLKB) tREF EFA (EFB) RENA1, RENA2 (RENB1, RENB2) QA0 - QA8 (QB0 - QB8) tOLZ OEA (OEB)
NOTE: 1. When tSKEW1 minimum specification, tFRL = tCLK + tSKEW1 When tSKEW1 < minimum specification, tFRL = 2tCLK + tSKEW1V or tCLK + tSKEW1 The Latency Timings apply only at the Empty Boundary (EFA, EFB = LOW).
D1 D0 (First Valid Write)
D2
D3
tFRL (1)
tENS
tA D0 tOE
tA D1
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Figure 7. First Data Word Latency Timing
10
IDT72801/728211/72821/72831/72841/72851
NO WRITE WCLKA (WCLKB) DA0 - DA8 (DB0 - DB8) tWFF FFA (FFB) tENS WENA1 (WENB1) tENS WENA2 (WENB2) (If Applicable) RCLKA (RCLKB) tENH RENA1 (RENB2) OEA LOW (OEB) QA0 - QA8 (QB0 - QB8) tENS tENH tENH tWFF tSKEW1
Commercial And Industrial Temperature Range
NO WRITE tSKEW1 NO WRITE
tDS
tDH
tWFF
tENS
(1)
tENS
(1)
tENH tENS
tA tA 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
WCLKA (WCLKB) tDS DA0 - DA8 (DB0 - DB8) tENS WENA1, (WENB1) tENS WENA2 (WENB2) (If Applicable) tSKEW1 RCLKA (RLCKB) tREF EFA (EFB) tREF tREF tENH tENS tENH DATA WRITE 1 tENH tENS tDS DATA WRITE 2 tENH
tFRL
(1)
tSKEW1
tFRL
(1)
RENA1, RENA2 (RENB1, RENB2) OEA (OEB) QA0-QA8 (QB0-QB8) LOW tA DATA IN OUTPUT REGISTER DATA READ
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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 (EFA, EFB = LOW).
Figure 9. Empty Flag Timing
11
IDT72801/728211/72821/72831/72841/72851
tCLKH WCLKA (WCLKB) tENS WENA1 (WENB1) tENS WENA2 (WENB2) (If Applicable) tENH tENH tCLKL
Commercial And Industrial Temperature Range
(4)
tPAF PAFA (PAFB) Full - (m+1) words in FIFO
(1)
Full - m words in FIFO tSKEW2
(2)
(3)
tPAF
RCLKA (RCLKB) tENS RENA1, RENA2 (RENB1, RENB2) tENH
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NOTES: 1. m = PAF offset. 2. (256-m) words for the IDT72801; (512-m) words the IDT72811; (1,024-m) words for the IDT72821; (2,048-m) words for the IDT72831; (4,096-m) words for the IDT72841; or (8,192-m) words for the IDT72851. 3. tSKEW2 is the minimum time between a rising RCLKA (RCLKB) edge and a rising WCLKA (WCLKB) edge for PAFA (PAFB) to change during that clock cycle. If the time between the rising edge of RCLKA (RCLKB) and the rising edge of WCLKA (WCLKB) is less than tSKEW2, then PAFA (PAFB) may not change state until the next WCLKA (WCLKB) rising edge. 4. If a write is performed on this rising edge of the write clock, there will be Full - (m-1) words in FIFO A (B) when PAFA (PAFB) goes LOW.
Figure 10. Programmable Full Flag Timing
tCLKH WCLKA (WCLKB)
tCLKL
tENS WENA1 (WENB1) tENS WENA2 (WENB2) (If Applicable)
tENH
tENH
PAEA, PAEB
n words in FIFO
(1) (2)
n+1 words in FIFO tPAE
(3)
tSKEW2 RCLKA (RCLKB)
tPAE
tENS RENA1, RENA2 (RENB1, RENB2)
tENH
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NOTES: 1. n = PAE offset. 2. tSKEW2 is the minimum time between a rising WCLKA (WCLKB) edge and a rising RCLKA (RCLKB) edge for PAEA (PAEB) to change during that clock cycle. If the time between the rising edge of WCLKA (WCLKB) and the rising edge of RCLKA (RCLKB) is less than tSKEW2, then PAEA (PAEB) may not change state until the next RCLKA (RCLKB) rising edge. 3. If a read is performed on this rising edge of the read clock, there will be Empty + (n-1) words in FIFO A (B) when PAEA (PAEB) goes LOW.
Figure 11. Programmable Empty Flag Timing
12
IDT72801/728211/72821/72831/72841/72851
tCLK tCLKL WCLKA (WCLKB) tENS LDA (LDB) tENS WENA1 (WENB1) tDS DA0 - DA7 (DB0 - DB7) PAE OFFSET (LSB) PAE OFFSET (MSB) tDH tENH
Commercial And Industrial Temperature Range
PAF OFFSET (LSB)
PAF OFFSET (MSB)
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Figure 12. Write Offset Register Timing
tCLK tCLKH RCLKA (RCLKB) tENS LDA (LDB) tENS RENA1, RENA2 (RENB1, RENB2) tA QA0 - QA7 (QB0 - QB7) DATA IN OUTPUT REGISTER EMPTY OFFSET (LSB) EMPTY OFFSET (MSB) FULL OFFSET (LSB) FULL OFFSET (MSB) 3034 drw 14 tENH tCLKL
Figure 13. Read Offset Register Timing
13
IDT72801/728211/72821/72831/72841/72851
Commercial And Industrial Temperature Range
can be grounded (see Figure 14). In this configuration, the Write Enable 2/ Load WENA2/LDA (WENB2/LDB) pin is set LOW at Reset so that the pin operates as a control to load and read the programmable flag offsets.
RSA (RSB)
OPERATING CON.IGURATIONS
SINGLE DEVICE CONFIGURATION -- When FIFO A (B) is in a Single Device Configuration, the Read Enable 2 RENA2 (RENB2) control input
WCLKA (WCLKB) WENA1 (WENB1) WENA2/LDA (WENB2/LDB) DA0 - DA8 (DB0 - DB8) FFA (FFB) PAFA (PAFB) IDT 72801 72811 72821 72831 72841 72851 FIFO A (B)
RCLKA (RCLKB) RENA1 (RENB1) OEA (OEB) QA0 - QA8 (QB0 - QB8) EFA (EFB) PAEA (PAEB)
RENA2 (RENB2)
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Figure 14. Block Diagram of One of the IDT72801/72811/72821/72831/72841/72851's two FIFOs configured as a single device
WIDTH EXPANSION CONFIGURATION -- Word width may be increased simply by connecting the corresponding input control signals of FIFOs A and B. A composite flag should be created for each of the endpoint status flags EFA and EFB, also FFA and FFB). The partial status flags PAEA, PAFB, PAEA and PAFB can be detected from any one device. Figure 15 demonstrates an 18-bit word width using the two FIFOs contained in one IDT72801/72811/72821/72831/72841/72851. Any word width can
9
be attained by adding additional IDT72801/72811/72821/72831/72841/ 72851s. When these devices are in a Width Expansion Configuration, the Read Enable 2 (RENA2 and RENB2) control inputs can be grounded (see Figure 15). In this configuration, the Write Enable 2/Load (WENA2/LDA, WENB2/LDB) pins are set LOW at Reset so that the pin operates as a control to load and read the programmable flag offsets.
RESET RSA DATA IN WRITE CLOCK WRITE ENABLE WRITE ENABLE/LOAD FULL FLAG 18 9 DA0 - DA8 WCLKA WENA1 WENA2/LDA FFA FFB DB0 - DB8 RSB EMPTY FLAG READ CLOCK READ ENABLE OUTPUT ENABLE
RAM ARRAY A 256x9 512x9 1,024x9 2,048x9 4,096x9 8,192x9
EFA EFB RAM RCLKA ARRAY RCLKB B WCLKB 256x9 RENB1 RENA1 WENB1 512x9 1,024x9 OEB OEA1 2WENB2/LDB 2,048x9 4,096x9 8,192x9 QB0 - QB8
9
18
DATA OUT
RENA2
QA0 - QA8 RENB2
9
3034 drw 16
Figure 15. Block diagram of the two FIFOs contained in one IDT72801/72811/ 72821/72831/72841/72851 configured for an 18-bit width-expansion
14
IDT72801/728211/72821/72831/72841/72851
Commercial And Industrial Temperature Range
data according to type, sending one kind to FIFO A and the other kind to FIFO B. Then, at the outputs, each data type is transferred to its appropriate destination. Additional IDT72801/72811/72821/72831/72841/72851s permit more than two priority levels. Priority buffering is particularly useful in network applications.
TWO PRIORITY DATA BU..ER CON.IGURATION
The two FIFOs contained in the IDT72801/72811/72821/72831/72841/ 72851 can be used to prioritize two different types of data shared on a system bus. When writing from the bus to the FIFO, control logic sorts the intermixed
Control Logic
9
RAM ARRAY A RCLKA WCLKA OEA WENA1 RENA QA0-QA8 WENA2 RENA2 IDT 72801 72811 72821 72831 72841 72851 RAM ARRAY B WCLKB RCLKB WENB1 OEB2 RENB1 DA0-DA8
9
Image Processing Card Clock Address Control I/O Data
Data
Processor Clock Address Control Data
9
VCC
Control Logic
9-bit bus
Voice Processing Card Clock
Control Logic
RAM
9
Address Control I/O Data
DB0-DB8
9
QB0-QB8 WENB2 RENB2
Data
9
3034 drw 17
VCC
Figure 16. Block Diagram of Two Priority Configuration
BIDIRECTIONAL CON.IGURATION
The two FIFOs of the IDT72801/72811/72821/72831/72841/72851 can be used to buffer data flow in two directions. In the example that follows, a
processor can write data to a peripheral controller via FIFO A, and, in turn, the peripheral controller can write the processor via FIFO B.
VCC
RAM ARRAY A WENA2 RENA2 WCLKA WENA1
9
RCLKA OEA Peripheral Controller DMA Clock
Control Logic
Processor Clock Address Control Data
9
9-bit bus
9-bit bus
RENA1 DA0-DA8 QA0-QA8 IDT 72801 72811 72821 72831 72841 72851 RAM ARRAY B
9
Control Logic
Address Control I/O Data Data
9
RCLKB RENB1
WENB1
RAM
9
9
WCLKB OEB QB0-QB8 DB0-DB8 RENB2 WENB2
9
3034 drw 18
Figure 17. Block Diagram of Bidirectional Configuration
15
DEPTH EXPANSION -- IDT72801/72811/72821/72831/72841/72851 can be adapted to applications that require greater than 256/512/1,024/ 2,048/4,096/8,192 words. The existence of double enable pins on the read and write ports allow depth expansion. The Write Enable 2/Load (WENA2, WENB2) pins are used as a second write enables 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 FIFOs operate in the Depth Expansion configuration when the following conditions are met: 1. WENA2/LDA and WENB2/LDB pins are held HIGH during Reset so that these pins operate as second Write Enables. 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.
ORDERING IN.ORMATION
IDT XXXXX Device Type X Power XX Speed XX Package X Process/ Temperature Range BLANK I(1) PF TF 10 15 25 L 72801 72811 72821 72831 72841 72851
NOTES: 1. Industrial temperature range product for 15ns and 25ns speed grade are available as a standard device.
Commercial (0 C to +70 C) Industrial (-40 C to +85 C) Thin Quad Flatpack (TQFP, PN64-1) Slim Thin Quad Flatpack(STQFP, PP64-1) Commercial Only Commercial and Industrial Commercial and Industrial Clock Cycle Time (tCLK), Speed in Nanoseconds
Low Power 256 x 9 Dual SyncFIFO 512 x 9 Dual SyncFIFO 1,024 x 9 Dual SyncFIFO 2,048 x 9 Dual SyncFIFO 4,096 x 9 Dual SyncFIFO 8,192 x 9 Dual SyncFIFO
3034 drw 19
DATASHEET DOCUMENT HISTORY
04/24/2001 pgs. 4, 5 and 16
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 e-mail: FIFOhelp@idt.com PF Pkg: www.idt.com/docs/PSC4036.pdf TF Pkg: www.idt.com/docs/PSC4046.pdf
The SyncFIFO is a trademark and the IDT logo is a registered trademark of Integrated Device Technology, Inc.
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