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| CMOS SyncFIFO 64 x 36 Integrated Device Technology, Inc. IDT723611 FEATURES: * Free-running CLKA and CLKB may be asynchronous or coincident (permits simultaneous reading and writing of data on a single clock edge) * 64 x 36 storage capacity * Synchronous data buffering from Port A to Port B * Mailbox bypass register in each direction * Programmable Almost-Full (AF) and Almost-Empty (AE) flags * Microprocessor Interface Control Logic * Full Flag (FF) and Almost-Full (AF) flags synchronized by CLKA * Empty Flag (EF) and Almost-Empty (AE) flags synchronized by CLKB * Passive parity checking on each Port * Parity Generation can be selected for each Port * Supports clock frequencies up to 67MHz * Fast access times of 10ns * Available in 132-pin Plastic Quad Flatpack (PQF) or space-saving 120-pin Thin Quad Flatpack (PF) * Low-power advanced CMOS technology * Industrial temperature range (-40oC to +85oC) is available, tested to military elecrical specifications DESCRIPTION: The IDT723611 is a monolithic, high-speed, low-power, CMOS Synchronous (clocked) FIFO memory which supports clock frequencies up to 67MHz and has read access times as fast as 10ns. The 64 x 36 dual-port FIFO buffers data from Port A to Port B. The FIFO has flags to indicate empty and full conditions, and two programmable flags, Almost-Full (AF) and Almost-Empty (AE), to indicate when a selected number of words is stored in memory. Communication between each port can take place through two 36-bit mailbox registers. Each FUNCTIONAL BLOCK DIAGRAM CLKA W/RA ENA MBA CSA Port-A Control Logic Parity Gen/Check Parity Generation MBF1 PEFB PGB RST ODD/ Mail 1 Register Input Register Reset Logic EVEN 36 64 x 36 SRAM Output Register * 36 A0 - A35 Write Pointer Read Pointer B0 - B35 FF AF FIFO Status Flag Logic Programmable Flag Offset Registers EF AE FS0 FS1 PGA PEFA MBF2 Parity Gen/Check Mail 2 Register CLKB Port-B Control Logic W/RB ENB MBB 3024 drw 01 CSB SyncFIFO is a trademark and the IDT logo is a registered trademark of Integrated Device Technology, Inc. COMMERCIAL TEMPERATURE RANGE (c)1997 Integrated Device Technology, Inc. For latest information contact IDT's web site at www.idt.com or fax-on-demand at 408-492-8391. MAY 1997 DSC-3024/4 1 IDT723611 CMOS SyncFIFOTM 64 x 36 COMMERCIAL TEMPERATURE RANGES DESCRIPTION (CONTINUED) 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 may be used in parallel to create wider data paths. The IDT723611 is a synchronous (clocked) FIFO, meaning 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 asyn- chronous or coincident. The enables for each port are arranged to provide a simple bidirectional interface between microprocessors and/or buses with synchronous control. The Full-Flag (FF) and Almost-Full (AF) flag of the FIFO are two-stage synchronized to the port clock that writes data into its array (CLKA). The Empty Flag (EF) and Almost-Empty (AE) flag of the FIFO are two-stage synchronized to the port clock that reads data from its array. The IDT723611 is characterized for operation from 0C to 70C. PIN CONFIGURATION 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 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 NC NC 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 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 EF AE NC ENA CLKA W/RA VCC PGA AF FF CSA MBA FS1 FS0 ODD/EVEN MBF1 PEFB PGB VCC W/RB CLKB ENB GND NC NC NC NC MBB PEFA MBF2 CSB RST NC 3024 drw 02 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 TQFP (PN120-1, order code: PF) TOP VIEW 2 IDT723611 CMOS SyncFIFOTM 64 x 36 COMMERCIAL TEMPERATURE RANGES PIN CONFIGURATION (CONTINUED) MBA FS1 FS0 ODD/EVEN ENA CLKA W/RA VCC PGA PGB VCC W/RB CLKB ENB PEFA GND MBF2 MBF1 GND NC NC NC NC MBB AF FF CSA PEFB GND RST 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 NC NC 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 * NC NC CSB 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 AE EF 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 3024 drw 03 PQFP (PQ132-1, order code: PQF) TOP VIEW *Electrical pin 1 in center of beveled edge. Pin 1 identifier in corner. 3 IDT723611 CMOS SyncFIFOTM 64 x 36 COMMERCIAL TEMPERATURE RANGES PIN DESCRIPTION Symbol A0-A35 Name Port-A Data Almost-Empty Flag I/O Description I/O 36-bit bidirectional data port for side A. O Programmable almost-empty flag synchronized to CLKB. It is LOW when the number of words in the FIFO is less than or equal to the value in the offset register, X. O Programmable almost-full flag synchronized to CLKA. It is LOW when the number of empty locations in the FIFO is less than or equal to the value in the offset register, X. I/O 36-bit bidirectional data port for side B. I CLKA is a continuous clock that synchronizes all data transfers through port-A and can be aynchronous or coincident to CLKB. FF and AF are synchronized to the LOW-to-HIGH transition of CLKA. I CLKB is a continuous clock that synchronizes all data transfers through port-B and can be asynchronous or coincident to CLKA. EF and AE are synchronized to the LOW-to-HIGH transition of CLKB. I 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. I AE AF B0-B35 CLKA Almost-Full Flag. Port-B Data. Port-A Clock CLKB Port-B Clock CSA CSB EF Port-A Chip Select Port-B Chip Select CSB 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. Empty Flag O ENA ENB Port-A Enable Port-B Enable Full Flag I I O FF When EF is LOW, the FIFO is empty, and reads from its memory are disabled. Data can be read from the FIFO to its output register when EF is HIGH. EF 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 FIFO 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. FF is synchronized to the LOW-to-HIGH transition of CLKA. When FF is LOW, the FIFO is full, and writes to its memory are disabled. FF is forced LOW when the device is reset and is set HIGH by the second LOW-to-HIGH transition of CLKA after reset. The LOW-to-HIGH transition of RST latches the values of FS0 and FS1, which loads one of four preset values into the almost-full and almost-empty offset register (X). A HIGH level on MBA chooses a mailbox register for a port-A read or write operation. 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 the FIFO 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 LOW-to-HIGH transition of CLKB when a port-B read is selected and MBB is HIGH. MBF1 is set HIGH when the device is reset. EF is synchronized to the LOW-to-HIGH transition of CLKB. FS1, FS0 Flag-Offset Selects I MBA MBB Port-A Mailbox Select Port-B Mailbox Select I I MBF1 Mail1 Register Flag O 4 IDT723611 CMOS SyncFIFOTM 64 x 36 COMMERCIAL TEMPERATURE RANGES PIN DESCRIPTION (CONTINUED) Symbol Name Mail2 Register Flag I/O O Description MBF2 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 LOW. MBF2 is set HIGH by a LOW-to-HIGH transition of CLKA when a portA read is selected and MBA is HIGH. MBF2 is set HIGH when the device is EVEN PEFA ODD/ Odd/Even Parity Select Port-A Parity Error Flag PEFB Port-B Parity Error Flag PGA Port-A Parity Generation PGB Port-B Parity Generation RST Reset W/RA Port-A Write/Read Select Port-B Write/Read Select 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. O When any byte applied to terminals A0-A35 fails parity, PEFA is LOW. (Port A) 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 CSA LOW, ENA HIGH, W/RA LOW, MBA HIGH, and PGA HIGH, the PEFA flag is forced HIGH regardless of the state of A0-A35 inputs. O When any byte applied to terminals B0-B35 fails parity, PEFB is LOW. (Port B) Bytes are organized as B0-B8, B9-B17, B18-B26, B27-B35, 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 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 CSB LOW, ENB HIGH, W/RB LOW, MBB HIGH, and PGB HIGH, the PEFB flag is forced HIGH regardless of the state of the B0-B35 inputs I Parity is generated for mail2 register reads from port A when PGA is HIGH. 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. I 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. I To reset the device, four LOW-to-HIGH transitions of CLKA and four LOW-toHIGH transitions of CLKB must occur while RST is LOW. This sets the AF, MBF1, and MBF2 flags HIGH and the EF, AE, and FF flags LOW. The LOWto-HIGH transition of RST latches the status of the FS1 and FS0 inputs to select almost-full and almost-empty flag offset. I 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. I 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. I W/RB 5 IDT723611 CMOS SyncFIFOTM 64 x 36 COMMERCIAL TEMPERATURE RANGES ABSOLUTE MAXIMUM RATINGS OVER OPERATING FREE-AIR TEMPERATURE RANGE (UNLESS OTHERWISE NOTED)(1) Symbol VCC VI (2) (2) 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 Operating Free Air Temperature Range Storage Temperature Range Commercial -0.5 to 7 -0.5 to VCC+0.5 -0.5 to VCC+0.5 20 50 50 500 0 to 70 -65 to 150 Unit V V V mA mA mA mA C C VO IIK IOK IOUT ICC TA TSTG 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 0 Min. Max. Unit 4.5 2 0.8 -4 8 70 5.5 V V V mA mA C ELECTRICAL CHARACTERISTICS OVER RECOMMENDED OPERATING FREE-AIR TEMPERATURE RANGE (UNLESS OTHERWISE NOTED) Parameter VOH VOL ILI ILO ICC VCC = 4.5V, VCC = 4.5 V, VCC = 5.5 V, VCC = 5.5 V, VCC = 5.5 V, Test Conditions IOH = -4 mA IOL = 8 mA VI = VCC or 0 VO = VCC or 0 IO = 0 mA, VI = VCC or GND Outputs HIGH Outputs LOW Outputs Disabled CIN COUT VI = 0, VO = 0, f = 1 MHz f = 1 MHZ 4 8 Min. 2.4 0.5 50 50 60 130 60 pF pF Typ.(1) Max. Unit V V A A mA Notes: 1. All typical values are at VCC = 5 V, TA = 25C. 6 IDT723611 CMOS SyncFIFOTM 64 x 36 COMMERCIAL TEMPERATURE RANGES TIMING REQUIREMENTS OVER RECOMMENDED RANGES OF SUPPLY VOLTAGE AND OPERATING FREE-AIR TEMPERATURES IDT723611L15 IDT723611L20 IDT723611L30 Min. Max. Min. Max. Min. Max. - 15 6 6 4 6 4 4 4 5 5 1 1 1 1 0 6 4 8 9 - - - - - (2) Symbol fS tCLK tCLKH tCLKL tDS tENS1 tENS2 tENS3 tPGS tRSTS tFSS tDH tENH1 tENH2 tENH3 tPGH tRSTH tFSH tSKEW1 (3) Parameter Clock Frequency, CLKA or CLKB Clock Cycle Time, CLKA or CLKB Pulse Duration, CLKA or CLKB HIGH Pulse Duration, CLKA or CLKB LOW Setup Time, A0-A35 before CLKA and B0-B35 before CLKB Unit Mhz Mhz ns ns ns ns ns ns ns ns ns ns ns ns ns 66.7 - - - - - - - - - - - - - 20 8 8 5 6 5 5 5 6 6 1 1 1 1 0 6 4 8 16 50 - - - - - - - - - - - - - 30 12 12 6 7 6 6 6 7 7 1 1 1 1 33.4 - - - - - - - - - - - - CSA, W/RA, before CLKA; CSB, W/RB before CLKB ENA before CLKA; ENB before CLKB MBA before CLKA; ENB before CLKB Setup Time, ODD/EVEN and PGB before CLKB(1) Setup Time, RST LOW before CLKA or CLKB(2) Setup Time, FS0 and FS1 before RST HIGH Hold Time, A0-A35 after CLKA and B0-B35 after CLKB CSA, W/RA after CLKA; CSB, W/RB after CLKB ENA after CLKA; ENB after CLKB MBA after CLKA; MBB after CLKB Hold TIme, ODD/EVEN and PGB after CLKB(1) Hold Time, RST LOW after CLKA or CLKB Hold Time, FS0 and FS1 after RST HIGH Skew Time, between CLKA and CLKB for EF, FF - - - - - 0 7 4 10 20 - - - - - ns ns ns ns ns tSKEW2(3) Skew Time, between CLKA and CLKB for AE, AF Notes: 1. Only applies for a rising edge of CLKB that does a FIFO read. 2. Requirement to count the clock edge as one of at least four needed to reset a FIFO. 3. 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. 7 IDT723611 CMOS SyncFIFOTM 64 x 36 COMMERCIAL TEMPERATURE RANGES SWITCHING CHARACTERISTICS OVER RECOMMENDED RANGES OF SUPPLY VOLTAGE AND OPERATING FREE-AIR TEMPERATURE, CL = 30 pF IDT723611L15 IDT723611L20 IDT723611L30 Min. Max. Min. Max. Min. Max. - 2 2 2 2 2 1 66.7 10 10 10 10 10 9 - 2 2 2 2 2 1 50 12 12 12 12 12 12 - 2 2 2 2 2 1 33.4 15 15 15 15 15 15 Symbol fS tA tWFF tREF tPAE tPAF tPMF Parameter Clock Frequency, CLKA or CLKB Access Time, CLKB to B0-B35 Propagation Delay Time, CLKA to FF Propagation Delay Time, CLKB to EF Unit MHz ns ns ns ns ns ns Propagation Delay Time, CLKB to AE Propagation Delay Time, CLKA to AF 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(1) and CLKB to A0-A35(2) Propagation Delay Time, 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 tPMR tMDV tPDPE tPOPE tPOPB(3) 3 1 3 3 2 12 11 12 11 12 3 1 3 3 2 14 11.5 13 12 13 3 1 3 3 2 16 12 14 14 15 ns ns ns ns ns Propagation Delay Time, ODD/EVEN to Parity Bits (A8, A17, A26, A35) and (B8, B17, B26, B35) Propagation Delay Time, CSA, ENA, W/RA, MBA, or PGAto PEFA; CSB, ENB, W/RB, MBB, or PGB to PEFB tPEPE 1 12 1 13 1 15 ns tPEPB(3) Propagation Delay Time, CSA, ENA W/RA, MBA, or PGA to Parity Bits (A8, A17, A26, A35); CSB, ENB, W/RB, MBB, or PGB to Parity Bits (B8, B17, B26, B35) Propagation Delay Time, RST to AE LOW and (AF, MBF1, MBF2) HIGH 3 14 3 15 3 16 ns tRSF tEN 1 2 15 10 1 2 20 12 1 2 30 14 ns ns 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 tDIS 1 9 1 10 1 11 ns Notes: 1. Writing data to the mail1 register when the B0-B35 outputs are active and MBB is HIGH. 2. Writing data to the mail2 register when the A0-A35 outputs are active and MBA is HIGH. 3. Only applies when reading data from a mail register. 8 IDT723611 CMOS SyncFIFOTM 64 x 36 COMMERCIAL TEMPERATURE RANGES SIGNAL DESCRIPTION RESET (RST RST) The IDT723611 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 the FIFO and forces the fullflag (FF) LOW, the empty flag (EF) LOW, the almost-empty flag (AE) LOW, and the almost-full flag (AF) HIGH. A reset also forces the mailbox flags (MBF1, MBF2) HIGH. After a reset, FF is set HIGH after two LOW-to-HIGH transitions of CLKA. Almost-Full and Almost-Empty Flag Offset Register (X) 16 12 8 4 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 offset register (X) with the value selected by the flag select (FS0, FS1) inputs. The values that can be loaded into the register are shown in Table 1. FIFO WRITE/READ OPERATION The state of the 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 A0-A35 outputs are active when both CSA and W/RA are LOW. Data is loaded into the FIFO from the A0-A35 inputs on a LOW-toHIGH transition of CLKA when CSA is LOW, W/RA is HIGH, ENA is HIGH, MBA is LOW, and FF 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 high-impedance 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 read from the FIFO 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 EF is HIGH (see Table 3). Port Functions None None FIFO Write Mail1 Write None None None Mail2 Read (set MBF2 HIGH) FS1 H H L L FS0 H L H L RST Table 1. Flag Programming CSA H L L L L L L L W/RA R 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, Mail2 Register Active, Mail2 Register Active, Mail2 Register Active, Mail2 Register Table 2. Port-A Enable Function Table CSB H L L L L L L L W/RB R 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, FIFO Output Register Active, FIFO Output Register Active, Mail1 Register Active, Mail1 Register Port Functions None None None Mail2 Write None FIFO Read None Mail1 Read (set MBF1 HIGH) Table 3. Port-B Enable Function Table 9 IDT723611 CMOS SyncFIFOTM 64 x 36 COMMERCIAL 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's chip select and write/read select can change states during the setup and hold-time window of the cycle. SYNCHRONIZED FIFO FLAGS Each FIFO flag is synchronized to its port clock through two flip-flop stages. This is done to improve the flags' reliability by reducing the probability of mestastable events on their outputs when CLKA and CLKB operate asynchronously to one another. FF and AF are synchronized to CLKA. EF and AE are synchronized to CLKB. Table 4 shows the relationship to the flags to the FIFO. EMPTY FLAG (EF EF) The FIFO empty flag is synchronized to the port clock that reads data from its array (CLKB). 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 FIFO read pointer is incremented each time a new word is clocked to its 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 the FIFO can be read to the FIFO output register in a minimum of three port-B clock (CLKB) cycles. 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 CLKB cycles have not elapsed since the time the word was written. The empty flag of the FIFO is set HIGH by the second LOW-to-HIGH transition of CLKB, and the new data word can be read to the FIFO output register in the following cycle. A LOW-to-HIGH transition on CLKB begins the first synchronized cycle of a write if the clock transition occurs at time tSKEW1 or greater after the write. Otherwise, the subsequent CLKB cycle can be the first synchronization cycle (see figure 4). FULL FLAG (FF FF) The FIFO full flag is synchronized to the port clock that writes data to its array (CLKA). When the full flag is HIGH, an SRAM location is free 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 the FIFO, its write pointer is incremented. The state machine that controls the 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 the FIFO, its previous memory location is ready to be written in a minimum of three port-A clock cycles. Therefore, a full flag is LOW if less than two CLKA cycles have elapsed since the next memory write location has been read. The second LOW-to-HIGH transition on CLKA after the read sets the full flag HIGH and data can be written in the following clock cycle. A LOW-to-HIGH transition on CLKA 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 (see figure 5). ALMOST-EMPTY FLAG (AE AE) The FIFO almost empty-flag is synchronized to the port clock that reads data from its array (CLKB). The state machine that controls the almost-empty flag monitors a write pointer and read 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). The 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 on the port-B clock (CLKB) 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 CLKB cycles have not elapsed since the write that filled the memory to the (X+1) level. The almost-empty flag is set HIGH by the second CLKB LOW-to-HIGH transition after the FIFO write that fills memory to the (X+1) level. A LOW-to-HIGH transition on CLKB 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 CLKB cycle can be the first synchronization cycle (see figure 6). ALMOST FULL FLAG (AF AF) The FIFO almost-full flag is synchronized to the port clock that writes data to its array (CLKA). The state machine that controls an almost-full flag monitors a write pointer and read pointer comparator that indicates when the FIFO SRAM status is almost full, almost full-1, or almost full-2. The almostfull state is defined by the value of the almost-full and almost10 Synchronized Number of Words in the FIFO 0 1 to X (X+1) to [64-(X+1)] (64-X) to 63 64 to CLKB Synchronized to CLKA EF L H H H H AE L L H H H AF H H H L L FF H H H H L Table 4. FIFO Flag Operation Note: X is the value in the almost-empty flag and almost-full flag register. IDT723611 CMOS SyncFIFOTM 64 x 36 COMMERCIAL TEMPERATURE RANGES empty offset register (X). This register is loaded with one of four preset values during a device reset (see reset above). The 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 on the port-A clock (CLKA) 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 CLKA cycles have not elapsed since the read that reduced the number of words in memory to [64-(X+1)]. The almost-full flag is set HIGH by the second CLKA LOW-to-HIGH transition after the FIFO read that reduces the number of words in memory to [64-(X+1)]. A LOW-to-HIGH transition on CLKA 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 CLKA cycle can be the first synchronization cycle (see figure 7). MAILBOX REGISTERS Two 36-bit bypass registers are on the IDT723611 to pass command and control information between port A and port B. 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 A0-A35 data to the mail1 register when port-A write is selected by CSA, W/RA, and ENA with MBA HIGH. A LOW-to-HIGH transition on CLKB writes B0-B35 data to the mail2 register when port-B write is selected by CSB, W/RB, and ENB with MBB HIGH. Writing data to a mail register sets its corresponding flag (MBF1 or MBF2) LOW. Attempted writes to a mail register are ignored while its mail flag is LOW. When the port-B data (B0-B35) outputs are active, the data on the bus comes from the FIFO output register when the portB mailbox select (MBB) input is LOW and from the mail1 register when MBB is HIGH. Mail2 data is always present on the port-A data (A0-A35) outputs when they are active. 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 with MBB HIGH. The mail2 register flag (MBF2) is set HIGH by a LOW-to-HIGH transition on CLKA when a port-A read is selected by CSA, W/RA, and ENA with MBA 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 (A0-A35) inputs and port-B (B0-B35) inputs 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 flags 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, and port-B bytes are arranged as B0-B8, B9-B17, B18-B26, and B27-B35. 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 its 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 port-A read from the mail2 register with parity generation is selected with CSA LOW, ENA HIGH, W/RA LOW, MBA HIGH, and PGA HIGH, the port-A 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 port-B reads (PGB=HIGH). When a port-B read from the mail1 register with parity generation is selected with CSB LOW, ENB HIGH, W/ RB LOW, 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 generate select (PGB) enables the IDT723611 to generate parity bits for port reads from a FIFO or mailbox register. 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, B9B17, 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-B parity generate select (PGB) and ODD/EVEN have setup and hold time constraints to the port-B clock (CLKB) for a rising edge of CLKB 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 port-B 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 the port parity generate select (PGA, PGB) is HIGH. Generating parity for mail register data does not change the contents of the register. 11 IDT723611 CMOS SyncFIFOTM 64 x 36 COMMERCIAL TEMPERATURE RANGES CLKA tRSTH CLKB tRSTS tFSS tFSH RST FS1,FS0 0,1 tWFF tWFF FF EF AE AF MBF1, MBF2 tRSF tREF tPAE tPAF 3024 drw 04 Figure 1. Device Reset Loading the X Register with the Value of Eight tCLK tCLKH CLKA tCLKL FF CSA tENS1 tENS1 tENH1 tENH1 W/RA tENS3 MBA tENS2 ENA tDS A0 - A35 ODD/ W1 tDH W2 No Operation tENH2 tENS2 tENH2 tENS2 tENH2 tENH3 EVEN PEFA tPDPE Valid tPDPE Valid 3024 drw 05 Figure 2. FIFO Write Cycle Timing 12 IDT723611 CMOS SyncFIFOTM 64 x 36 COMMERCIAL TEMPERATURE RANGES tCLK tCLKH CLKB tCLKL EF CSB W/RB (HIGH) tENS2 MBB tENH2 ENB tMDV tEN B0 - B35 PGB, ODD/ tA Previous Data tPGH tPGS Word 1 tPGS tPGH tA tENS2 tENH2 tENS2 No Operation Word 2 tDIS tENH2 EVEN Figure 3. FIFO Read Cycle Timing 3024 drw 06 tCLK tCLKH tCLKL CLKA CSA WRA MBA LOW HIGH tENS3 tENS2 tENH3 tENH2 ENA FFA A0 - A35 HIGH tDS W1 tDH tSKEW1(1) CLKB tCLK tCLKH tCLKL 1 2 tREF tREF EF CSB W/RB MBB ENB LOW LOW LOW Empty FIFO tENS2 tENH2 tA B0 -B35 W1 3024 drw 07 Note: 1. tSKEW1 is the minimum time between a rising CLKA edge and a rising CLKB edge for EF 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 EF HIGH may occur one CLKB cycle later than shown. Figure 4. EF Flag Timing and First Data Read when the FIFO is Empty 13 IDT723611 CMOS SyncFIFOTM 64 x 36 COMMERCIAL TEMPERATURE RANGES tCLK tCLKH CLKB tCLKL CSB W/RB MBB ENB LOW LOW LOW tENS2 tENH2 EFB B0 -B35 HIGH tA Previous Word in FIFO Output Register Next Word From FIFO tSKEW1(1) tCLKH CLKA 1 FIFO Full LOW HIGH tCLK tCLKL 2 tWFF tWFF FF CSA WRA MBA tENS3 tENS2 tENH3 tENH2 tDH To FIFO 3024 drw 08 ENA tDS A0 - A35 Note: 1. tSKEW1 is the minimum time between a rising CLKB edge and a rising CLKA edge for FF 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 FF HIGH may occur one CLKA cycle later than shown. Figure 5. FF Flag Timing and First Available Write when the FIFO is Full CLKA tENS2 ENA tSKEW2 CLKB (1) tENH2 1 2 tPAE tPAE (X+1) Words in FIFO AE ENB X Word in FIFO tENS2 tENH2 3024 drw 09 1. tSKEW2 is the minimum time between a rising CLKA edge and a rising CLKB edge for AE 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 AE may transition HIGH one CLKB cycle later than shown. 2. FIFO write (CSA = L, W/RA = H, MBA = L), FIFO read (CSB = L, W/RB = L, MBB = L). Figure 6. Timing for AE when the FIFO is Almost Empty Notes: 14 IDT723611 CMOS SyncFIFOTM 64 x 36 COMMERCIAL TEMPERATURE RANGES tSKEW2 CLKA tENS2 ENA tPAF tENH2 (1) 1 2 tPAF (64-X) Words in FIFO AF CLKB [64-(X+1)] Words in FIFO tENS2 ENB tENH2 1. tSKEW2 is the minimum time between a rising CLKA edge and a rising CLKB edge for AF 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 AF may transition HIGH one CLKB cycle later than shown. 2. FIFO write (CSA = L, W/RA = H, MBA = L), FIFO read (CSB = L, W/RB = L, MBB = L). Figure 7. Timing for AF when the FIFO is Almost Full Notes: 3024 drw 10 CLKA tENS1 tENH1 CSA W/RA MBA ENA A0 - A35 tDS W1 tDH CLKB MBF1 CSB W/RB MBB tPMF tPMF tENS2 ENB tEN B0 - B35 FIFO Output Register tMDV tPMR tENH2 tDIS W1 (Remains valid in Mail1 Register after read) 3024 drw 11 Note: 1. Port-B parity generation off (PGB = L) Figure 8. Timing for Mail1 Register and MBF1 Flag 15 IDT723611 CMOS SyncFIFOTM 64 x 36 COMMERCIAL TEMPERATURE RANGES CLKB tENS1 tENH1 CSB W/RB MBB ENB tDS W1 tDH B0 - B35 CLKA MBF2 CSA W/RA MBA tPMF tPMF tENS2 ENA tEN A0 - A35 tPMR tENH2 tDIS W1 (Remains valid in Mail2 Register after read) 3024 drw 12 Note: 1. Port-A parity generation off (PGA = L) Figure 9. Timing for Mail2 Register and MBF2 Flag ODD/ EVEN W/RA MBA PGA tPOPE tPOPE Valid Valid tPEPE tPEPE Valid 3024 drw 13 PEFA Valid Note: 1. CSA = L and ENA = H. Figure 10. ODD/EVEN W/RA, MBA, and PGA to PEFA Timing EVEN, 16 IDT723611 CMOS SyncFIFOTM 64 x 36 COMMERCIAL TEMPERATURE RANGES ODD/ EVEN W/RB MBB PGB tPOPE tPOPE Valid Valid tPEPE tPEPE Valid 3024 drw 14 PEFB Valid Note: 1. CSB = L and ENB = H. Figure 11. ODD/EVEN W/RB, MBB, and PGB to PEFB Timing EVEN, ODD/ EVEN CSA W/RA MBA PGA LOW tEN A8, A17, A26, A35 tPEPB Mail2 Data tPOPB Generated Parity tPEPB Generated Parity Mail2 Data 3024 drw 15 Note: 1. ENA = H. Figure 12. Parity Generation Timing when reading from the Mail2 Register ODD/ EVEN CSB W/RB MBB PGB LOW tEN B8, B17, B26, B35 tPEPB tMDV Mail1 Data tPOPB Generated Parity tPEPB Generated Parity Mail1 Data 3024 drw 16 Note: 1. ENB = H. Figure 13. Parity Generation Timing when reading from the Mail1 Register 17 IDT723611 CMOS SyncFIFOTM 64 x 36 COMMERCIAL TEMPERATURE RANGES TYPICAL CHARACTERISTICS SUPPLY CURRENT vs CLOCK FREQUENCY 400 VCC = 5.5 V 350 f data = 1/2 f s T A = 25 C 300 C L = 0 pF VCC = 5.0 V 250 I CC(f) - Supply Current - mA 200 VCC = 4.5 V 150 100 50 0 0 10 20 30 40 50 60 70 80 f clock - Clock Frequency - MHz Figure 14. 3024 drw 17 CALCULATING POWER DISSIPATION The ICC(f) data for the graph was taken while simultaneously reading and writing the FIFO on the IDT723611 with CLKA and CLKB operating at frequency 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 14, the maximum power dissipation (PT) of the IDT723611 may be calculated by: PT = VCC x ICC(f) + (CL x VOH - VOL)2 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 read or writes are occurring on the IDT723611, 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 18 IDT723611 CMOS SyncFIFOTM 64 x 36 COMMERCIAL TEMPERATURE RANGES PARAMETER MEASUREMENT INFORMATION 5V 1.1 k From Output Under Test 680 30 pF (1) PROPAGATION DELAY LOAD CIRCUIT 3V Timing Input tS Data, Enable Input 1.5 V 1.5 V GND th 3V 1.5 V GND Low-Level Input 1.5 V High-Level Input 1.5 V tW 1.5 V 3V GND 3V 1.5 V GND VOLTAGE WAVEFORMS SETUP AND HOLD TIMES VOLTAGE WAVEFORMS PULSE DURATIONS Output Enable tPLZ Low-Level Output 3V 1.5 V 1.5 V tPZL 1.5 V tPZH 1.5 V VOL VOH In-Phase Output GND 3 V Input 3V 1.5 V tPD 1.5 V 1.5 V GND tPD VOH 1.5 V VOL High-Level Output tPHZ OV VOLTAGE WAVEFORMS ENABLE AND DISABLE TIMES VOLTAGE WAVEFORMS PROPAGATION DELAY TIMES 3024 drw 18 Note: 1. Includes probe and jig capacitance. Figure 15. Load Circuit and Voltage Waveforms 19 IDT723611 CMOS SyncFIFOTM 64 x 36 COMMERCIAL TEMPERATURE RANGES ORDERING INFORMATION IDT XXXXXX Device Type X Power XX Speed X Package X Process/ Temperature Range BLANK Commercial (0C to +70C) PF PQF 15 20 30 Thin Quad Flat Pack (TQFP, PN120-1) Plastic Quad Flat Pack (PQFP, PQ132-1) Commercial Only Clock Cycle Time (tCLK) Speed in Nanoseconds L Low Power 723611 64 x 36 Synchronous FIFO 3024 drw 19 20 |
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