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CMOS SyncBiFIFOTM 64 x 36 x 2
FEATURES:
* * * * *
IDT723612
* * * * * * * *
Free-running CLKA and CLKB can be asynchronous or coincident (simultaneous reading and writing of data on a single clock edge is permitted) Two independent clocked FIFOs (64 x 36 storage capacity each) buffering data in opposite directions Mailbox bypass Register for each FIFO Programmable Almost-Full and Almost-Empty Flags Microprocessor interface control logic EFA, FFA, AEA, and AFA flags synchronized by CLKA EFB, FFB, AEB, and AFB flags synchronized by CLKB Passive parity checking on each port Parity generation can be selected for each port
Supports clock frequencies up to 67 MHz Fast access times of 10ns Available in 132-pin plastic quad flat package (PQF) or spacesaving 120-pin thin quad flat package (TQFP) Industrial temperature range (-40C to +85C) is available
DESCRIPTION:
The IDT723612 is a monolithic high-speed, low-power CMOS bi-directional clocked FIFO memory. It supports clock frequencies up to 67 MHz and has read access times as fast as 10ns. Two independent 64 x 36 dual-port SRAM FIFOs on board the chip buffer data in opposite directions. Each FIFO has flags to indicate empty and full conditions and two programmable flags (Almost-Full and Almost-Empty) to indicate when a selected number of words is stored in
FUNCTIONAL BLOCK DIAGRAM
CLKA CSA W/RA ENA MBA Port-A Control Logic Mail 1 Register Parity Gen/Check MBF1 PEFB PGB
Parity Generation
Input Register
RST ODD/ EVEN Device Control
RAM ARRAY 64 x 36
Output Register
36
Write Pointer FFA AFA
36
Read Pointer EFB AEB
Status Flag Logic FIFO1 Programmable Flag Offset Register FIFO2 Status Flag Logic Read Pointer
Parity Generation
FS0 FS1 A0 - A35 EFA AEA
B0 - B36 FFB AFB
36
Write Pointer
Output Register
RAM ARRAY 64 x 36
PGA Parity Gen/Check
Mail 2 Register CLKB CSB W/RB ENB MBB
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PEFA MBF2
Input Register
Port-B Control Logic
IDT and the IDT logo are registered trademarks of Integrated Device Technology, Inc. SyncBiFIFO is a trademark of Integrated Device Technology, Inc.
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
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All rights reserved.
MARCH 2002
DSC-3136/1
(c) 2002 Integrated Device Technology, Inc.
Product specifications subject to change without notice.
IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
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memory. Communication between each port can bypass the FIFOs via two 36-bit mailbox registers. Each mailbox register has a flag to signal when new mail has been stored. Parity is checked passively on each port and may be ignored if not desired. Parity generation can be selected for data read from each port. Two or more devices can be used in parallel to create wider data paths. This device is a clocked FIFO, which means each port employs a synchronous interface. All data transfers through a port are gated to the LOW-to-HIGH transition of a port clock by enable signals. The clocks for each port are
independent of one another and can be asynchronous or coincident. The enables for each port are arranged to provide a simple bi-directional interface between microprocessors and/or buses with synchronous control. The Full Flag (FFA, FFB) and Almost-Full (AFA, AFB) flag of a FIFO are two-stage synchronized to the port clock that writes data to its array. The Empty Flag (EFA, EFB) and Almost-Empty (AEA, AEB) flag of a FIFO are two stage synchronized to the port clock that reads data from its array. The IDT723612 is characterized for operation from 0C to 70C.
PIN CONFIGURATIONS
AFA FFA CSA ENA CLKA W/RA VCC PGA PEFA GND MBF2 MBA FS1 FS0 ODD/EVEN RST GND NC NC NC NC MBB MBF1 GND PEFB PGB VCC W/RB CLKB ENB CSB FFB AFB
VCC A24 A25 A26 GND A27 A28 A29 VCC A30 A31 A32 GND A33 A34 A35 GND B35 B34 B33 GND B32 B31 B30 VCC B29 B28 B27 GND B26 B25 B24 VCC
51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83
GND AEA EFA A0 A1 A2 GND A3 A4 A5 A6 VCC A7 A8 A9 GND A10 A11 VCC A12 A13 A14 GND A15 A16 A17 A18 A19 A20 GND A21 A22 A23
18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 132 131 130 129 128 127 126 125 124 123 122 121 120 119 118 117
*
116 115 114 113 112 111 110 109 108 107 106 105 104 103 102 101 100 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84
GND AEB EFB B0 B1 B2 GND B3 B4 B5 B6 VCC B7 B8 B9 GND B10 B11 VCC B12 B13 B14 GND B15 B16 B17 B18 B19 B20 GND B21 B22 B23
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* Electrical pin 1 in center of beveled edge. Pin 1 identifier in corner. PQFP(2) (PQ132-1, ORDER CODE: PQF) TOP VIEW
NOTE: 1. NC - No internal connection 2. Uses Yamaichi socket IC51-1324-828
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IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
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PIN CONFIGURATIONS (CONTINUED)
A23 A22 A21 GND A20 A19 A18 A17 A16 A15 A14 A13 A12 A11 A10 GND A9 A8 A7 VCC A6 A5 A4 A3 GND A2 A1 A0 EFA AEA
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
120 119 118 117 116 115 114 113 112 111 110 109 108 107 106 105 104 103 102 101 100 99 98 97 96 95 94 93 92 91
A24 A25 A26 VCC A27 A28 A29 GND A30 A31 A32 A33 A34 A35 GND B35 B34 B33 B32 B31 B30 GND B29 B28 B27 VCC B26 B25 B24 B23
90 89 88 87 86 85 84 83 82 81 80 79 78 77 76 75 74 73 72 71 70 69 68 67 66 65 64 63 62 61
B22 B21 GND B20 B19 B18 B17 B16 B15 B14 B13 B12 B11 B10 GND B9 B8 B7 VCC B6 B5 B4 B3 GND B2 B1 B0 EFB AEB AFB
AFA FFA CSA ENA CLKA W/RA VCC PGA PEFA MBF2 MBA FS1 FS0 ODD/EVEN RST GND NC NC NC NC MBB MBF1 PEFB PGB VCC W/RB CLKB ENB CSB FFB
NOTE: 1. NC - No internal connection
31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
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TQFP (PN120-1, ORDER CODE: PF) TOP VIEW
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IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
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PIN DESCRIPTION
Symbol A0-A35 AEA AEB AFA AFB B0-B35 CLKA Name Port-A Data Almost-Empty Flag Port-B Almost-Empty Flag Port-A Almost-Full Flag Port-B Almost-Empty Flag Port-B Data. Port-A Clock I/O I/O O (Port A) O (Port B) O (Port A) O (Port B) I/O I Description 36-bit bidirectional data port for side A. Programmable Almost-Empty flag synchronized to CLKA. It is LOW when the number of words in the FIFO2 is less than or equal to the value in the offset register, X. Programmable Almost-Full flag synchronized to CLKB. It is LOW when the number of words in FIFO1 is less than or equal to the value in the offset register, X. Programmable Almost-Full flag synchronized to CLKA. It is LOW when the number of empty locations in FIFO1 is less than or equal to the value in the offset register, X. Programmable Almost-Full flag synchronized to CLKB. It is LOW when the number of empty locations in FIFO2 is less than or equal to the value in the offset register, X. 36-bit bidirectional data port for side B. CLKA is a continuous clock that synchronizes all data transfers through port-A and can be asynchronous or coincident to CLKB. EFA, FFA, AFA, and AEA are synchronized to the LOW-to-HIGH transition of CLKA. CLKB is a continuous clock that synchronizes all data transfers through port-B and can be asynchronous or coincident to CLKA. EFB, FFB, AFB, and AEB are synchronized to the LOWto-HIGH transition of CLKB. CSA must be LOW to enable a LOW-to-HIGH transition of CLKA to read or write data on port-A. The A0-A35 outputs are in the high-impedance state when CSA is HIGH. B must be LOW to enable a LOW-to-HIGH transition of CLKB to read or write data on port-B. The B0-B35 outputs are in the high-impedance state when CSB is HIGH. EFA is synchronized to the LOW-to-HIGH transition of CLKA. When EFA is LOW, FIFO2 is empty, and reads from its memory are disabled. Data can be read from FIFO2 to the output register when EFA is HIGH. EFA is forced LOW when the device is reset and is set HIGH by the second LOW-to-HIGH transition of CLKA after data is loaded into empty FIFO2 memory. EFB is synchronized to the LOW-to-HIGH transition of CLKB. When EFB is LOW, the FIFO1 is empty, and reads from its memory are disabled. Data can be read from FIFO1 to the output register when EFB is HIGH. EFB is forced LOW when the device is reset and is set HIGH by the second LOW-to-HIGH transition of CLKB after data is loaded into empty FIFO1 memory. ENA must be HIGH to enable a LOW-to-HIGH transition of CLKA to read or write data on port-A. ENB must be HIGH to enable a LOW-to-HIGH transition of CLKB to read or write data on port-B. FFA is synchronized to the LOW-to-HIGH transition of CLKA. When FFA is LOW, FIFO1 is full, and writes to its memory are disabled. FFA is forced LOW when the device is reset and is set HIGH by the second LOW-to-HIGH transition of CLKA after reset. FFB is synchronized to the LOW-to-HIGH transition of CLKB. When FFB is LOW, FIFO2 is full, and writes to its memory are disabled. FFB is forced LOW when the device is reset and is set HIGH by the second LOW-to-HIGH transition of CLKB after reset. The LOW-to-HIGH transition of RST latches the values of FS0 and FS1, which selects one of four preset values for the Almost-Full flag and almost-Empty flag. A HIGH level on MBA chooses a mailbox register for a port-A read or write operation. When the A0-A35 outputs are active, a HIGH level on MBA selects data from the mail2 register for output, and a LOW level selects FIFO2 output register data for output. A HIGH level on MBB chooses a mailbox register for a port-B read or write operation. When the B0-B35 outputs are active, a HIGH level on MBB selects data from the mail1 register for output, and a LOW level selects FIFO1 output register data for output. MBF1 is set LOW by a LOW-to-HIGH transition of CLKA that writes data to the mail1 register. Writes to the mail1 register are inhibited while MBF1 is set LOW. MBF1 is set HIGH by a LOWto-HIGH transition of CLKB when a port-B read is selected and MBB is HIGH. MBF1 is set HIGH when the device is reset. MBF2 is set LOW by a LOW-to-HIGH transition of CLKB that writes data to the mail2 register. Writes to the mail2 register are inhibited while MBF2 is set LOW. MBF2 is set HIGH by a LOW- toHIGH transition of CLKA when a port-A read is selected and MBA is HIGH. MBF2 is set HIGH when the device is reset.
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CLKB
Port-B Clock
I
CSA CSB EFA
Port-A Chip Select Port-B Chip Select Port-A Empty Flag
I I O (Port A)
EFB
Port-B Empty Flag
O (Port B)
ENA ENB FFA
Port-A Enable Port-B Enable Port-A Full Flag
I I O (Port A) O (Port B) I I
FFB
Port-B Full Flag
FS1, FS0 MBA
Flag-Offset Selects Port-A Mailbox Select Port-B Mailbox Select Mail1 Register Flag
MBB
I
MBF1
O
MBF2
Mail2 Register Flag
O
IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
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PIN DESCRIPTION (CONTINUED)
Symbol Name I/O Description
ODD/ EVEN PEFA
Odd/Even Parity Select Port-A Parity Error Flag
I
Odd parity is checked on each port when ODD/EVEN is HIGH, and even parity is checked when ODD/EVEN is LOW. ODD/EVEN also selects the type of parity generated for each port if parity generation is enabled for a read operation. When any byte applied to terminals A0-A35 fails parity, PEFA is LOW. Bytes are organized as A0-A8, A9-A17, A18-A26, and A27-A35, with the most significant bit of each byte serving as the parity bit. The type of parity checked is determined by the state of the ODD/EVEN input. The parity trees used to check the A0-A35 inputs are shared by the mail2 register to generate parity if parity generation is selected by PGA. Therefore, if a mail2 read with parity generation is setup by having W/RA LOW, MBA HIGH, and PGA HIGH, the PEFA flag is forced HIGH regardless of the A0-A35 inputs. When any byte applied to terminals B0-B35 fails parity, PEFB is LOW. Bytes are organized as B0-B8, B9-B17, B18-B26, B27-B35 with the most significant bit of each byte serving as theparity bit. The type of parity checked is determined by the state of the ODD/EVEN input. The parity trees used to check the B0-B35 inputs are shared by the mail1 register to generate parity if parity generation is selected by PGB. Therefore, if a mail1 read with parity generation is setup by having W/RB LOW, MBB HIGH, and PGB HIGH, the PEFB flag is forced HIGH regardless of the state of the B0-B35 inputs. Parity is generated for data reads from port A when PGA is HIGH. Generation The type of parity generated is selected by the state of the ODD/EVEN input. Bytes are organized as A0-A8, A9-A17, A18-A26, and A27-A35. The generated parity bits are output in the most significant bit of each byte. Parity is generated for data reads from port B when PGB is HIGH. The type of parity generated is selected by the state of the ODD/EVEN input. Bytes are organized as B0-B8, B9-B17, B18-B26, and B27-B35. The generated parity bits are output in the most significant bit of each byte. To reset the device, four LOW-to-HIGH transitions of CLKA and four LOW-to-HIGH transitions of CLKB must occur while RST is LOW. This sets the AFA, AFB, MBF1, and MBF2 flags HIGH and the EFA, EFB, AEA, AEB, FFA, and FFB flags LOW. The LOW-to-HIGH transition of RST latches the status of the FS1 and FS0 inputs to select Almost-Full and Almost-Empty flag offset. A HIGH selects a write operation and a LOW selects a read operation on port A for a LOW-to-HIGH transition of CLKA. The A0-A35 outputs are in the high-impedance state when W/RA is HIGH. A HIGH selects a write operation and a LOW selects a read operation on port B for a LOW-to-HIGH transition of CLKB. The B0-B35 outputs are in the high-impedance state when W/RB is HIGH.
O (Port A)
PEFB
Port-B Parity Error Flag
O (Port B)
PGA
Port-A Parity
I
PGB
Port-B Parity
I
RST
Reset
I
W/RA W/RB
Port-A Write/Read Select Port-B Write/Read Select
I I
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IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
ABSOLUTE MAXIMUM RATINGS OVER OPERATING FREE-AIR TEMPERATURE RANGE (UNLESS OTHERWISE NOTED)(2)
Symbol VCC VI(2) VO(2) IIK IOK IOUT ICC TSTG Rating Supply Voltage Range Input Voltage Range Output Voltage Range Input Clamp Current, (VI < 0 or VI > VCC) Output Clamp Current, (VO < 0 or VO > VCC) Continuous Output Current, (VO = 0 to VCC) Continuous Current Through VCC or GND Storage Temperature Range Commercial -0.5 to 7 -0.5 to VCC+0.5 -0.5 to VCC+0.5 20 50 50 500 -65 to 150 Unit V V V mA mA mA mA C
NOTES: 1. Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other conditions beyond those indicated under "Recommended Operating Conditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. 2. The input and output voltage ratings may be exceeded provided the input and output current ratings are observed.
RECOMMENDED OPERATING CONDITIONS
Symbol VCC VIH VIL IOH IOL TA Parameter Supply Voltage HIGH Level Input Voltage LOW-Level Input Voltage HIGH-Level Output Current LOW-Level Output Current Operating Free-air Temperature Min. 4.5 2 - - - 0 Max. 5.5 - 0.8 -4 8 70 Unit V V V mA mA C
ELECTRICAL CHARACTERISTICS OVER RECOMMENDED OPERATING FREE-AIR TEMPERATURE RANGE (UNLESS OTHERWISE NOTED)
Parameter VOH VOL ILI ILO ICC(2) CIN COUT VCC = 4.5V, VCC = 4.5V, VCC = 5.5V, VCC = 5.5V, VCC 5.5V, VI= 0, VO = 0, Test Conditions IOH = -4 mA IOL = 8 mA VI = VCC or 0 VO = VCC or 0 IO = 0 mA, f = 1 MHz f = 1 MHZ VI = VCC or GND Min. 2.4 -- -- -- -- -- -- Typ.(1) -- -- -- -- -- 4 8 Max. -- 0.5 50 50 1 -- -- Unit V V A A mA pF pF
NOTES: 1. All typical values are at VCC = 5V, TA = 25C. 2. For additional ICC information, see following page.
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IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
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400 VCC = 5.5V 350 fdata = 1/2 fS TA= 25C 300 mA CL = 0 pF VCC = 5.0V 250
Supply Current
200
VCC = 4.5V
ICC(f)
150
100
50
0 0 10 20 30 40 50 60 70
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80
fS Clock Frequency MHz
Figure 1. Typical Characteristics: Supply Current vs Clock Frequency
CALCULATING POWER DISSIPATION
The ICC(f) current for the graph in Figure 1 was taken while simultaneously reading and writing the FIFO on the IDT723612 with CLKA and CLKB set to fS. All data inputs and data outputs change state during each clock cycle to consume the highest supply current. Data outputs were disconnected to normalize the graph to a zero-capacitance load. Once the capacitance load per data-output channel is known, the power dissipation can be calculated with the equation below. With ICC(f) taken from Figure 1, the maximum power dissipation (PD) of the IDT723612 may be calculated by: PD = VCC x ICC(f) + (CL x VCC x (VOH - VOL) x fo) where: CL fo VOH VOL = = = = output capacitance load switching frequency of an output output HIGH level voltage output LOW level voltage
When no reads or writes are occurring on the IDT723612, the power dissipated by a single clock (CLKA or CLKB) input running at frequency fS is calculated by: PT = VCC x fS x 0.290 mA/MHz
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IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
(Commercial: VCC = 5.0V 10%, TA = 0C to +70C; Industrial; VCC = 5.0V 10%,TA = 40C to +85C)
DC ELECTRICAL CHARACTERISTICS OVER RECOMMENDED RANGES OF SUPPLY VOLTAGE AND OPERATING FREE-AIR TEMPERATURE
Commercial Symbol fS tCLK tCLKH tCLKL tDS tENS1 tENS2 tENS3 tPGS tRSTS tFSS tDH tENH1 tENH2 tENH3 tPGH tRSTH tFSH tSKEW1(4) tSKEW2(4) Parameter Clock Frequency, CLKA or CLKB Clock Cycle Time, CLKA or CLKB Pulse Duration, CLKA and CLKB HIGH Pulse Duration, CLKA and CLKB LOW Setup Time, A0-A35 before CLKA and B0-B35 before CLKB Setup Time, CSA, W/RA before CLKA; CSB, W/RB before CLKB Setup Time, ENA, before CLKA; ENB before CLKB Setup Time, MBA before CLKA: MBB before CLKB Setup Time, ODD/EVEN and PGA before CLKA; ODD/EVEN and PGB before CLKB(2 ) Setup Time, RST LOW before CLKA or CLKB(3) Setup Time, FS0/FS1 before RST HIGH Hold Time, A0-A35 after CLKA and B0-B35 after CLKB Hold Time, CSA W/RA after CLKA; CSB, W/RB after CLKB Hold Time, ENA, after CLKA; ENB after CLKB Hold Time, MBA after CLKA; MBB after CLKB Hold Time, ODD/EVEN and PGA after CLKA; ODD/EVEN and PGB after CLKB(2 ) Hold Time, RST LOW after CLKA or CLKB(3) Hold Time, FS0 and FS1 after RST HIGH Skew Time, between CLKA and CLKB for EFA, EFB, FFA, and FFB Skew Time, between CLKA and CLKB For AEA, AEB, AFA, and AFB IDT723612L15 Min. Max. - 66.7 15 - 6 6 4 6 4 4 4 5 5 2.5 2 2.5 1 1 5 4 8 14 - - - - - - - - - - - - - - - - - - Com'l & Ind'l(1) IDT723612L20 Min. Max. - 50 20 - 8 8 5 6 5 5 5 6 6 2.5 2 2.5 1 1 6 4 8 16 - - - - - - - - - - - - - - - - - - Unit MHz 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 20ns speed grade is available as a standard device. All other speed grades are available by special order. 2. Only applies for a clock edge that does a FIFO read. 3. Requirement to count the clock edge as one of at least four needed to reset a FIFO. 4. Skew time is not a timing constraint for proper device operation and is only included to illustrate the timing relationship between CLKA cycle and CLKB cycle.
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IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
(Commercial: VCC = 5.0V 10%, TA = 0C to +70C; Industrial; VCC = 5.0V 10%,TA = 40C to +85C)
SWITCHING CHARACTERISTICS OVER RECOMMENDED RANGES OF SUPPLY VOLTAGE AND OPERATING FREE-AIR TEMPERATURE, CL = 30PF
Commercial Symbol tA tWFF tREF tPAE tPAF tPMF tPMR tMDV tPDPE tPOPE tPOPB(4) tPEPE tPEPB(4) tRSF tEN tDIS Parameter Access Time, CLKA to A0-A35 and CLKB to B0-B35 Propagation Delay Time, CLKA to FFA and CLKB to FFB Propagation Delay Time, CLKA to EFA and and CLKB to EFB Propagation Delay Time, CLKA to AEA and CLKB to AEB Propagation Delay Time, CLKA to AFA and CLKB to AFB Propagation Delay Time, CLKA to MBF1 LOW or MBF2 HIGH and CLKB to MBF2 LOW or MBF1 HIGH Propagation Delay Time, CLKA to B0-B35(2) and CLKB to A0-A35(3) Propagation Delay Time, MBA to A0-A35 valid and MBB to B0-B35 valid Propagation Delay Time, A0-A35 valid to PEFA valid; B0-B35 valid to PEFB valid Propagation Delay Time, ODD/EVEN to PEFA and PEFB Propagation Delay Time, ODD/EVEN to parity bits (A8, A17, A26, A35) and (B8, B17, B26, B35) Propagation Delay Time, W/RA, CSA, ENA, MBA or PGA to PEFA; W/RB, CSB, ENB, MBB, PGB to PEFB Propagation Delay Time, W/RA, CSA, ENA, MBA or PGA to parity bits ( A8, A17, A26, A35); W/RB, CSB, bits (B8, B17, B26, B35) ENB, MBB or PGB to parity Propagation Delay Time, RST to (AEA, AEB) LOW and (AFA, AFB, MBF1, MBF2) HIGH Enable Time, CSA and W/RA LOW to A0-A35 active and CSB LOW and W/RB HIGH to B0-B35 active Disable Time, CSA or W/RA HIGH to A0-A35 at high impedance and CSB HIGH or W/RB LOW to B0-B35 at high impedance. IDT723612L15 Min. Max. 2 10 2 10 2 2 2 1 3 1 3 3 2 1 3 1 2 1 10 10 10 9 11 11 10 11 11 11 12 15 10 8 Com'l & Ind'l(1) IDT723612L20 Min. Max. 2 12 2 12 2 2 2 1 3 1 3 3 2 1 3 1 2 1 12 12 12 12 13 11.5 11 12 12 12 13 20 12 9 Unit ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns
NOTES: 1. Industrial temperature range product for 20ns speed grade is available as a standard device. All other speed grades are available by special order. 2. Writing data to the mail1 register when the B0-B35 outputs are active and MBB is HIGH. 3 Writing data to the mail2 register when the A0-A35 outputs are active and MBA is HIGH. 4. Only applies when reading data from a mail register.
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IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
SIGNAL DESCRIPTIONS
RESET The IDT723612 is reset by taking the Reset (RST) input LOW for at least four port-A clock (CLKA) and four port-B Clock (CLKB) LOW-to-HIGH transitions. The Reset input can switch asynchronously to the clocks. A device reset initializes the internal read and write pointers of each FIFO and forces the Full Flags (FFA, FFB) LOW, the Empty Flags (EFA, EFB) LOW, the AlmostEmpty flags (AEA, AEB) LOW and the Almost-Full flags (AFA, AFB) HIGH. A reset also forces the Mailbox Flags (MBF1, MBF2) HIGH. After a reset, FFA is set HIGH after two LOW-to-HIGH transitions of CLKA and FFB is set HIGH after two LOW-to-HIGH transitions of CLKB. The device must be reset after power up before data is written to its memory.
A LOW-to-HIGH transition on the RST input loads the Almost-Full and Almost-Empty registers (X) with the values selected by the Flag Select (FS0, FS1) inputs. The values that can be loaded into the registers are shown in Table 1. FIFO WRITE/READ OPERATION The state of port-A data A0-A35 outputs is controlled by the port-A Chip Select (CSA) and the port-A Write/Read select (W/RA). The A0-A35 outputs are in the high-impedance state when either CSA or W/RA is HIGH. The A0A35 outputs are active when both CSA and W/RA are LOW. Data is loaded into FIFO1 from the A0-A35 inputs on a LOW-to-HIGH transition of CLKA when CSA is LOW, W/RA is HIGH, ENA is HIGH, MBA is LOW, and FFA is HIGH. Data is read from FIFO2 to the A0-A35 outputs by a LOW-to-HIGH transition of CLKA when CSA is LOW, W/RA is LOW, ENA is HIGH, MBA is LOW, and EFA is HIGH (see Table 2). The port-B control signals are identical to those of port A. The state of the port-B data (B0-B35) outputs is controlled by the port-B Chip Select (CSB) and the port-B Write/Read select (W/RB). The B0-B35 outputs are in the highimpedance state when either CSB or W/RB is HIGH. The B0-B35 outputs are active when both CSB and W/RB are LOW. Data is loaded into FIFO2 from the B0-B35 inputs on a LOW-to-HIGH transition of CLKB when CSB is LOW, W/RB is HIGH, ENB is HIGH, MBB is LOW, and FFB is HIGH. Data is read from FIFO1 to the B0-B35 outputs by a LOW-to-HIGH transition of CLKB when CSB is LOW, W/RB is LOW, ENB is HIGH, MBB is LOW, and EFB is HIGH (see Table 3).
TABLE 1 FLAG PROGRAMMING
FS1 H H L L FS0 H L H L RST ALMOST-FULL AND ALMOST-EMPTY FLAG OFFSET REGISTER (X) 16 12 8 4
TABLE 2 PORT-A ENABLE FUNCTION TABLE
CSA H L L L L L L L W/RA X H H H L L L L ENA X L H H L H L H MBA X X L H L L H H CLKA X X X X A0-A35 Outputs In High-Impedance State In High-Impedance State In High-Impedance State In High-Impedance State Active, FIFO2 Output Register Active, FIFO2 Output Register Active, Mail2 Register Active, Mail2 Register Port Functions None None FIFO1 Write Mail1 Write None FIFO2 Read None Mail2 Read (Set MBF2 HIGH)
TABLE 3 PORT-B ENABLE FUNCTION TABLE
CSB H L L L L L L L W/RB X H H H L L L L ENB X L H H L H L H MBB X X L H L L H H CLKB X X X X B0-B35 Outputs In High-Impedance State In High-Impedance State In High-Impedance State In High-Impedance State Active, FIFO1 Output Register Active, FIFO1 Output Register Active, Mail1 Register Active, Mail1 Register
10
Port Functions None None FIFO2 Write Mail2 Write None FIFO1 read None Mail1 Read (Set MBF1 HIGH)
IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
The setup and hold time constraints to the port clocks for the port Chip Selects (CSA, CSB) and Write/Read selects (W/RA, W/RB) are only for enabling write and read operations and are not related to high-impedance control of the data outputs. If a port enable is LOW during a clock cycle, the port chip select and write/read select may change states during the setup and hold time window of the cycle. SYNCHRONIZED FIFO FLAGS Each FIFO is synchronized to its port clock through two flip-flop stages. This is done to improve flag reliability by reducing the probability of metastable events on the output when CLKA and CLKB operate asynchronously to one another. EFA, AEA, FFA, and AFA are synchronized by CLKA. EFB, AEB, FFB, and AFB are synchronized to CLKB. Tables 4 and 5 show the relationship of each port flag to FIFO1 and FIFO2. EMPTY FLAGS (EFA, EFB) The Empty Flag of a FIFO is synchronized to the port clock that reads data from its array. When the Empty Flag is HIGH, new data can be read to the FIFO output register. When the Empty Flag is LOW, the FIFO is empty and attempted FIFO reads are ignored. The read pointer of a FIFO is incremented each time a new word is clocked to the output register. The state machine that controls an Empty Flag monitors a write-pointer and read-pointer comparator that indicates when the FIFO SRAM status is empty, empty+1, or empty+2. A word written to a FIFO can be read to the FIFO output register in a minimum of three cycles of the Empty Flag synchronizing clock. Therefore, an Empty Flag is LOW if a word in memory is the next data to be sent to the FIFO output register and two cycles of the port clock that reads data from the FIFO have not elapsed since the time the word was written. The Empty Flag of the FIFO is set HIGH by the second LOW-toHIGH transition of the synchronizing clock, and the new data word can be read to the FIFO output register in the following cycle. A LOW-to-HIGH transition on an Empty Flag synchronizing clock begins the first synchronization cycle of a write if the clock transition occurs at time tSKEW1 or greater after the write. Otherwise, the subsequent clock cycle can be the first synchronization cycle. FULL FLAG (FFA, FFB) The Full Flag of a FIFO is synchronized to the port clock that writes data to its array. When the Full Flag is HIGH, a memory location is free in the SRAM to receive new data. No memory locations are free when the Full Flag is LOW and attempted writes to the FIFO are ignored.
Each time a word is written to a FIFO, the write pointer is incremented. The state machine that controls a Full Flag monitors a write-pointer and read pointer comparator that indicates when the FIFO SRAM status is full, full-1, or full-2. From the time a word is read from a FIFO, the previous memory location is ready to be written in a minimum of three cycles of the Full Flag synchronizing clock. Therefore, a Full Flag is LOW if less than two cycles of the Full Flag synchronizing clock have elapsed since the next memory write location has been read. The second LOW-to-HIGH transition on the Full Flag synchronization clock after the read sets the Full Flag HIGH and the data can be written in the following clock cycle. A LOW-to-HIGH transition on a Full Flag synchronizing clock begins the first synchronization cycle of a read if the clock transition occurs at time tSKEW1 or greater after the read. Otherwise, the subsequent clock cycle can be the first synchronization cycle. ALMOST EMPTY FLAGS (AEA, AEB) The Almost-Empty flag of a FIFO is synchronized to the port clock that reads data from its array. The state machine that controls an Almost-Empty flag monitors a write-pointer comparator that indicates when the FIFO SRAM status is almost-empty, almost-empty+1, or almost-empty+2. The almost-empty state is defined by the value of the Almost-Full and Almost-Empty Offset register (X). This register is loaded with one of four preset values during a device reset (see Reset above). An Almost-Empty flag is LOW when the FIFO contains X or less words in memory and is HIGH when the FIFO contains (X+1) or more words. Two LOW-to-HIGH transitions of the Almost-Empty flag synchronizing clocks are required after a FIFO write for the Almost-Empty flag to reflect the new level of fill. Therefore, the Almost-Empty flag of a FIFO containing (X+1) or more words remains LOW if two cycles of the synchronizing clock have not elapsed since the write that filled the memory to the (X+1) level. An Almost-Empty flag is set HIGH by the second LOW-to-HIGH transition of the synchronizing clock after the FIFO write that fills memory to the (X+1) level. A LOW-to-HIGH transition of an Almost-Empty flag synchronizing clock begins the first synchronization cycle if it occurs at time tSKEW2 or greater after the write that fills the FIFO to (X+1) words. Otherwise, the subsequent synchronizing clock cycle can be the first synchronization cycle (see Figure 7 and 8). ALMOST FULL FLAGS (AFA, AFB) The Almost-Full flag of a FIFO is synchronized to the port clock that writes data to its array. The state machine that controls an Almost-Full flag monitors a write-pointer and read-pointer comparator that indicates when the FIFO
TABLE 4 FIFO1 FLAG OPERATION
Number of Words in the FIFO1(1) 0 1 to X (X+1) to [64-(X+1)] (64-X) to 63 64 Synchronized to CLKB EFB L H H H H AEB L L H H H Synchronized to CLKA AFA H H H L L FFA H H H H L
TABLE 5 FIFO2 FLAG OPERATION
Number of Words in the FIFO1(1) 0 1 to X (X+1) to [64-(X+1)] (64-X) to 63 64 Synchronized to CLKB EFA AEA L H H H H L L H H H Synchronized to CLKA AFB FFB H H H L L H H H H L
NOTE: 1. X is the value in the Almost-Empty flag and Almost-Full flag offset register.
11
IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
SRAM status is almost-full, almost-full-1, or almost-full-2. The almost-full state is defined by the value of the Almost-Full and Almost-Empty Offset register (X). This register is loaded with one of four preset values during a device reset (see Reset above). An Almost-Full flag is LOW when the FIFO contains (64-X) or more words in memory and is HIGH when the FIFO contains [64-(X+1)] or less words. Two LOW-to-HIGH transitions of the Almost-Full flag synchronizing clock are required after a FIFO read for the Almost-Full flag to reflect the new level of fill. Therefore, the Almost-Full flag of a FIFO containing [64-(X+1)] or less words remains LOW if two cycles of the synchronizing clock have not elapsed since the read that reduced the number of words in memory to [64-(X+1)]. An AlmostFull flag is set HIGH by the second LOW-to-HIGH transition of the synchronizing clock after the FIFO read that reduces the number of words in memory to [64(X+1)]. A second LOW-to-HIGH transition of an Almost-Full flag synchronizing clock begins the first synchronization cycle if it occurs at time tSKEW2 or greater after the read that reduces the number of words in memory to [64-(X+1)]. Otherwise, the subsequent synchronizing clock cycle can be the first synchronization cycle (see Figure 14 and 15). MAILBOX REGISTERS Each FIFO has a 36-bit bypass register to pass command and control information between port A and port B without putting it in queue. The Mailbox select (MBA, MBB) inputs choose between a mail register and a FIFO for a port data transfer operation. A LOW-to-HIGH transition on CLKA writes A0A35 data to the mail1 register when a port-A write is selected by CSA, W/RA, and ENA and MBA HIGH. A LOW-to-HIGH transition on CLKB writes B0-B35 data to the mail2 register when a port-B write is selected by CSB, W/RB, and ENB and MBB is HIGH. Writing data to a mail register sets the corresponding flag (MBF1 or MBF2) LOW. Attempted writes to a mail register are ignored while the mail flag is LOW. When a port's data outputs are active, the data on the bus comes from the FIFO output register when the port Mailbox-select input (MBA, MBB) is LOW and from the mail register when the port mailbox-select input is HIGH. The Mail1 register Flag (MBF1) is set HIGH by a LOW-to-HIGH transition on CLKB when a port-B read is selected by CSB, W/RB, and ENB and MBB is HIGH. The Mail2 register Flag (MBF2) is set HIGH by a LOW-to-HIGH transition on CLKA when port-A read is selected by CSA, W/RA, and ENA and MBA is HIGH. The data in a mail register remains intact after it is read and changes only when new data is written to the register. PARITY CHECKING The port-A inputs (A0-A35) and port-B inputs (B0-B35) each have four parity trees to check the parity of incoming (or outgoing) data. A parity failure on one or more bytes of the input bus is reported by a LOW level on the port Parity Error Flag (PEFA, PEFB). Odd or even parity checking can be selected, and the Parity Error Fags can be ignored if this feature is not desired. Parity status is checked on each input bus according to the level of the Odd/ Even parity (ODD/EVEN) select input. A parity error on one or more bytes of a port is reported by a LOW level on the corresponding port Parity Error Flag
(PEFA, PEFB) output. Port-A bytes are arranged as A0-A8, A9-A17, A18A26, and A27-A35 with the most significant bit of each byte used as the parity bit. Port-B bytes are arranged as B0-B8, B9-B17, B18-B26, and B27-B35, with the most significant bit of each byte used as the parity bit. When odd/even parity is selected, a port parity error flag (PEFA, PEFB) is LOW if any byte on the port has an odd/even number of LOW levels applied to the bits. The four parity trees used to check the A0-A35 inputs are shared by the mail2 register when parity generation is selected for port-A reads (PGA = HIGH). When a port-A read from the mail2 register with parity generation is selected with W/RA LOW, CSA LOW, ENA HIGH, MBA HIGH, and PGA HIGH, the portA Parity Error Flag (PEFA) is held HIGH regardless of the levels applied to the A0-A35 inputs. Likewise, the parity trees used to check the B0-B35 inputs are shared by the mail1 register when parity generation is selected for portB reads (PGB = HIGH). When a port-B read from the mail1 register with parity generation is selected with W/RB LOW, CSB LOW, ENB HIGH, MBB HIGH, and PGB HIGH, the port-B parity error flag (PEFB) is held HIGH regardless of the levels applied to the B0-B35 inputs. PARITY GENERATION A HIGH level on the port-A Parity Generate select (PGA) or port-B Parity Generate select (PGB) enables the IDT723612 to generate parity bits for port reads from a FIFO or mailbox register. Port-A bytes are arranged as A0A8, A9-A17, A18-26, and A27-A35, with the most significant bit of each byte used as the parity bit. Port-B bytes are arranged as B0-B8, B9-B17, B18-B26, and B27-B35, with the most significant bit of each byte used as the parity bit. A write to a FIFO or mail register stores the levels applied to all thirty-six inputs regardless of the state of the Parity Generate select (PGA, PGB) inputs. When data is read from a port with parity generation selected, the lower eight bits of each byte are used to generate a parity bit according to the level on the ODD/ EVEN select. The generated parity bits are substituted for the levels originally written to the most significant bits of each byte as the word is read to the data outputs. Parity bits for FIFO data are generated after the data is read from SRAM and before the data is written to the output register. Therefore, the port-A parity generate select (PGA) and Odd/Even parity select (ODD/EVEN) have setup and hold time constraints to the port-A Clock (CLKA) and the port-B Parity Generate select (PGB) and ODD/EVEN have setup and hold-time constraints to the port-B Clock (CLKB). These timing constraints only apply for a rising clock edge used to read a new word to the FIFO output register. The circuit used to generate parity for the mail1 data is shared by the portB bus (B0-B35) to check parity and the circuit used to generate parity for the mail2 data is shared by the port-A bus (A0-A35) to check parity. The shared parity trees of a port are used to generate parity bits for the data in a mail register when the port Write/Read select (W/RA, W/RB) input is LOW, the port mail select (MBA, MBB) input is HIGH, Chip Select (CSA, CSB) is LOW, Enable (ENA, ENB) is HIGH, and port Parity Generate select (PGA, PGB) is HIGH. Generating parity for mail register data does not change the contents of the register.
12
IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
CLKA tRSTH CLKB tRSTS RST FS1,FS0 tWFF FFA tREF EFA tWFF FFB tREF EFB tPAE AEA tPAF AFA MBF1, MBF2 AEB tPAF AFB
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tFSS
tFSH
0,1 tWFF
tWFF
tRSF tPAE
Figure 2. Device Reset Loading the X Register with the Value of Eight
13
IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
tCLK tCLKH CLKA FFA HIGH CSA tENS1 W/RA tENS3 MBA tENS2 ENA tDS A0 - A35 ODD/ EVEN PEFA
NOTE: 1. Written to FIFO1.
tCLKL
tENS1
tENH1 tENH1 tENH3 tENH2 tDH W1
(1)
tENS2
tENH2
tENS2
tENH2
W2(1)
No Operation
tPDPE Valid
tPDPE Valid
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Figure 3. Port-A Write Cycle Timing for FIFO1
tCLK tCLKH CLKB FFB HIGH CSB tENS1 W/RB tENS3 MBB tENS2 ENB tDS B0 - B35 ODD/ EVEN PEFB
NOTE: 1. Written to FIFO2.
tCLKL
tENS1
tENH1 tENH1 tENH3 tENH2 tDH W1
(1)
tENS2
tENH2
tENS2
tENH2
W2(1)
No Operation
tPDPE Valid
tPDPE Valid
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Figure 4. Port-B Write Cycle Timing for FIFO2
14
IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
tCLK tCLKH CLKB EFB CSB W/RB tENS2 MBB tENH2 ENB B0 - B35 PGB, ODD/ EVEN
NOTE: 1. Read from FIFO1.
tCLKL
HIGH
tENS2
tENH2
tENS2 No Operation Word 2 (1)
tENH2 tDIS
tMDV tEN
tA Previous Data tPGH tPGS
(1)
tA Word 1
(1)
tPGS
tPGH
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Figure 5. Port-B Read Cycle Timing for FIFO1
tCLK tCLKH CLKA EFA CSA W/RA tENS2 MBA tENH2 ENA tMDV A0 - A35 PGA, ODD/ EVEN
NOTE: 1. Read from FIFO2.
tCLKL
HIGH
tENS2
tENH2
tENS2 No Operation Word 2
(1)
tENH2
tA Previous Data tPGH tPGS
(1)
tEN
tA Word 1 tPGS
(1)
tDIS
tPGH
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Figure 6. Port-A Read Cycle Timing for FIFO2
15
IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
tCLK tCLKH tCLKL CLKA CSA LOW WRA HIGH tENS3 MBA tENS2 ENA FFA HIGH A0 - A35 tDS W1
(1)
tENH3 tENH2
tDH tCLK tCLKH tCLKL 1
tSKEW1 CLKB EFB CSB LOW W/RB LOW
2 tREF
tREF
FIFO1 Empty
MBB LOW tENS2 ENB tA B0 -B35 W1
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tENH2
NOTE: 1. tSKEW1 is the minimum time between a rising CLKA edge and a rising CLKB edge for EFB to transition HIGH in the next CLKB cycle. If the time between the rising CLKA edge and rising CLKB edge is less than tSKEW1, then the transition of EFB HIGH may occur one CLKB cycle later than shown.
Figure 7. EFB Flag Timing and First Data Read when FIFO1 is Empty
16
IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
tCLK tCLKH tCLKL CLKB CSB LOW tENS3 tENS2 ENB FFB HIGH B0 - B35 tDS W1
(1)
W/RB HIGH MBB
tENH3 tENH2
tDH tCLK tCLKH tCLKL 1
tSKEW1 CLKA EFA CSA W/RA MBA ENA LOW LOW LOW FIFO2 Empty
2 tREF
tREF
tENS2
tENH2 tA
A0 -A35
W1
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NOTE: 1. tSKEW1 is the minimum time between a rising CLKB edge and a rising CLKA edge for EFA to transition HIGH in the next CLKA cycle. If the time between the rising CLKB edge and rising CLKA edge is less than tSKEW1, then the transition of EFA HIGH may occur one CLKA cycle later than shown.
Figure 8. EFA Flag Timing and First Data Read when FIFO2 is Empty
17
IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
tCLKH CLKB CSB W/RB MBB ENB EFB B0 - B35 HIGH LOW LOW LOW
tCLK
tCLKL
tENS2
tENH2
tA
Next Word From FIFO1
Previous Word in FIFO1 Output Register
tSKEW1(1) CLKA FFA CSA WRA MBA LOW HIGH FIFO1 Full
tCLKH 1
tCLK
tCLKL 2 tWFF tWFF
tENS3 tENS2
tENH3 tENH2 tDH
To FIFO1
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ENA tDS A0 - A35
NOTE: 1. tSKEW1 is the minimum time between a rising CLKB edge and a rising CLKA edge for FFA to transition HIGH in the next CLKA cycle. If the time between the rising CLKB edge and rising CLKA edge is less than tSKEW1, then FFA may transition HIGH one CLKA cycle later than shown.
Figure 9. FFA Flag Timing and First Available Write when FIFO1 is Full
18
IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
tCLK tCLKH CLKA CSA W/RA MBA ENA EFA A0 - A35 HIGH LOW LOW LOW tENS2 tENH2 tCLKL
tA
Next Word From FIFO2
Previous Word in FIFO2 Output Register
tSKEW1(1) CLKB FFB CSB W/RB MBB LOW HIGH FIFO2 Full
tCLKH 1
tCLK
tCLKL 2 tWFF tWFF
tENS3 tENS2
tENH3 tENH2 tDH
To FIFO2
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ENB tDS B0 - B35
NOTE: 1. tSKEW1 is the minimum time between a rising CLKA edge and a rising CLKB edge for FFB to transition HIGH in the next CLKB cycle. If the time between the rising CLKA edge and rising CLKB edge is less than tSKEW1, then FFB may transition HIGH one CLKB cycle later than shown.
Figure 10. FFB Flag Timing and First Available Write when FIFO2 is Full
CLKA ENA
tENS2
tENH2 tSKEW2(1)
CLKB AEB ENB
1
X Word in FIFO1
2 tPAE
(X+1) Words in FIFO1
tPAE tENS2 tENH2
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NOTES: 1. tSKEW2 is the minimum time between a rising CLKA edge and a rising CLKB edge for AEB to transition HIGH in the next CLKB cycle. If the time between the rising CLKA edge and rising CLKB edge is less than tSKEW2, then AEB may transition HIGH one CLKB cycle later than shown. 2. FIFO1 Write (CSA = LOW, W/RA = HIGH, MBA = LOW), FIFO1 read (CSB = LOW, W/RB = LOW, MBB = LOW).
Figure 11. Timing for AEB when FIFO1 is Almost Empty
19
IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
CLKB tENS2 ENB tSKEW2(1) CLKA AEA ENA
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tENH2
1
X Words in FIFO2
2 tPAE
(X+1) Words in FIFO2
tPAE tENS2 tENH2
NOTES: 1. tSKEW2 is the minimum time between a rising CLKB edge and a rising CLKA edge for AEA to transition HIGH in the next CLKA cycle. If the time between the rising CLKB edge and rising CLKA edge is less than tSKEW2, then AEA may transition HIGH one CLKA cycle later than shown. 2. FIFO2 Write (CSB = LOW, W/RB = HIGH, MBB = LOW), FIFO2 read (CSA = LOW, W/RA = LOW, MBA = LOW).
Figure 12. Timing for AEA when FIFO2 is Almost Empty
tSKEW2(1) CLKA tENS2 ENA tPAF AFA CLKB tENS2 ENB
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1 tENH2
2
tPAF (64-X) Words in FIFO1
[64-(X+1)] Words in FIFO1
tENH2
NOTES: 1. tSKEW2 is the minimum time between a rising CLKA edge and a rising CLKB edge for AFA to transition HIGH in the next CLKA cycle. If the time between the rising CLKA edge and rising CLKB edge is less than tSKEW2, then AFA may transition HIGH one CLKB cycle later than shown. 2. FIFO1 Write (CSA = LOW, W/RA = HIGH, MBA = LOW), FIFO1 read (CSB = LOW, W/RB = LOW, MBB = LOW).
Figure 13. Timing for AFA when FIFO1 is Almost Full
tSKEW2(1) CLKB tENS2 ENB tPAF AFB CLKA tENS2 ENA
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1 tENH2
2
tPAF (64-X) Words in FIFO2
[64-(X+1)] Words in FIFO2
tENH2
NOTES: 1. tSKEW2 is the minimum time between a rising CLKB edge and a rising CLKA edge for AFB to transition HIGH in the next CLKB cycle. If the time between the rising CLKB edge and rising CLKA edge is less than tSKEW2, then AFB may transition HIGH one CLKA cycle later than shown. 2. FIFO2 Write (CSB = LOW, W/RB = HIGH, MBB = LOW), FIFO2 read (CSA = LOW, W/RA = LOW, MBA = LOW).
Figure 14. Timing for AFB when FIFO2 is Almost Full
20
IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
CLKA tENS1 CSA tENS1 W/RA tENS1 MBA tENS1 ENA A0 - A35 CLKB tPMF MBF1 CSB W/RB MBB tENS2 ENB tEN B0 - B35 FIFO1 Output Register tMDV tPMR tDIS W1 (Remains valid in Mail1 Register after read)
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tENH1 tENH1 tENH1 tENH1 tDS W1 tDH
tPMF
tENH2
NOTE: 1. Port-B parity generation off (PGB = LOW).
Figure 15. Timing for Mail1 Register and MBF1 Flag
21
IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
W1 (Remains valid in Mail2 Register after read)
NOTE: 1. Port-A parity generation off (PGA = LOW).
Figure 16. Timing for Mail2 Register and MBF2 Flag
ODD/ EVEN W/RA MBA PGA PEFA Valid
tPOPE Valid
tPOPE Valid
tPEPE
tPEPE Valid
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NOTE: 1. ENA is HIGH, and CSA is LOW.
Figure 17. ODD/EVEN W/RA, MBA, and PGA to PEFA Timing
22
IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
ODD/ EVEN W/RB MBB PGB tPOPE PEFB Valid Valid tPOPE Valid tPEPE tPEPE Valid
3136 drw21
NOTE: 1. ENB is HIGH, and CSB is LOW.
Figure 18. ODD/EVEN W/RB, MBB, and PGB to PEFB Timing
ODD/ EVEN CSA W/RA MBA PGA A8, A17, A26, A35
NOTE: 1. ENA is HIGH.
LOW
tEN
tPEPB tMDV Mail2 Data
tPOPB Generated Parity
tPEPB Generated Parity
Mail2 Data
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Figure 19. Parity Generation Timing when Reading from Mail2 Register
ODD/ EVEN CSB LOW W/RB MBB PGB B8, B17, B26, B35
NOTE: 1. ENB is HIGH.
tEN
tPEPB tMDV Mail1 Data
tPOPB Generated Parity
tPEPB Generated Parity
Mail1 Data
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Figure 20. Parity Generation Timing when Reading from Mail1 Register
23
IDT723612 CMOS SYNCBiFIFOTM 64 x 36 x 2
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
PARAMETER MEASUREMENT INFORMATION
5V 1.1 k From Output Under Test 680 30 pF
(1)
LOAD CIRCUIT 3V Timing Input tS Data, Enable Input 1.5 V 1.5 V GND th 3V 1.5 V GND VOLTAGE WAVEFORMS SETUP AND HOLD TIMES Output Enable tPLZ Low-Level Output 3V 1.5 V 1.5 V tPZL 1.5 V tPZH 1.5 V VOL VOH High-Level Output tPHZ VOLTAGE WAVEFORMS ENABLE AND DISABLE TIMES
NOTE: 1. Includes probe and jig capacitance.
High-Level Input
3V 1.5 V tW 3V 1.5 V GND
Low-Level Input
1.5 V VOLTAGE WAVEFORMS PULSE DURATIONS
1.5 V
GND
GND 3 V
Input
3V 1.5 V tPD 1.5 V GND tPD VOH 1.5 V 1.5 V VOL
OV
In-Phase Output
VOLTAGE WAVEFORMS PROPAGATION DELAY TIMES
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Figure 21. Load Circuit and Voltage Waveforms
24
ORDERING INFORMATION
IDT XXXXXX Device Type X Power XX Speed X Package X Process/ Temperature Range BLANK I(1) PF PQF 15 20 L 723612 Commercial (0C to +70C) Industrial (40C to +85C) Thin Quad Flat Pack (TQFP, PN120-1) Plastic Quad Flat Pack (PQFP, PQ132-1) Commercial Only Com'l & Ind'l Low Power Clock Cycle Time (tCLK) Speed in Nanoseconds
64 x 36 x 2 SyncBiFIFOTM
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NOTE: 1. Industrial temperature range product for 20ns speed grade is available as a standard device. All other speed grades are available by special order.
DATASHEET DOCUMENT HISTORY
03/05/2002 pgs. 1, 8, 9 and 25. 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
25
for TECH SUPPORT: e-mail: FIFOhelp@idt.com Phone: (408) 330-1753

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