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| HIGH-SPEED 3.3V 32K x 16 DUAL-PORT STATIC RAM Features: x x x IDT70V27S/L x x x True Dual-Ported memory cells which allow simultaneous access of the same memory location High-speed access - Industrial: 35ns (max.) - Commercial: 15/20/25/35/55ns (max.) Low-power operation - IDT70V27S Active: 500mW (typ.) Standby: 3.3mW (typ.) - IDT70V27L Active: 500mW (typ.) Standby: 660W (typ.) Separate upper-byte and lower-byte control for bus matching capability Dual chip enables allow for depth expansion without external logic x x x x x x x x IDT70V27 easily expands data bus width to 32 bits or more using the Master/Slave select when cascading more than one device M/S = VIH for BUSY output flag on Master, M/S = VIL for BUSY input on Slave Busy and Interrupt Flags On-chip port arbitration logic Full on-chip hardware support of semaphore signaling between ports Fully asynchronous operation from either port LVTTL-compatible, single 3.3V (0.3V) power supply Available in 100-pin Thin Quad Flatpack (TQFP), 108-pin Ceramic Pin Grid Array (PGA), and 144-pin Fine Pitch BGA (fpBGA) Industrial temperature range (-40C to +85C) is available for selected speeds Functional Block Diagram R/WL UBL CE0L R/WR UBR CE0R CE1L OEL LBL CE1R OER LBR I/O8-15L I/O0-7L BUSYL (1,2) I/O Control I/O Control I/O8-15R I/O0-7R BUSYR (1,2) A14L A0L Address Decoder A14L A0L CE0L 32Kx16 MEMORY ARRAY 70V27 Address Decoder A14R A0R CE1L OEL ARBITRATION INTERRUPT SEMAPHORE LOGIC A14R A0R CE0R CE1R OER R/WL SEM L INT L (2) R/WR SEMR NOTES: 1) BUSY is an input as a Slave (M/S=VIL) and an output as a Master (M/S=VIH). 2) BUSY and INT are non-tri-state totem-pole outputs (push-pull). M/S (2) INTR 3603 drw 01 (2) JANUARY 2001 6.01 1 (c)2000 Integrated Device Technology, Inc. DSC 3603/7 IDT 70V27S/L High-Speed 3.3V 32K x 16 Dual-Port Static RAM Commercial and Industrial Temperature Range Description: The IDT70V27 is a high-speed 32K x 16 Dual-Port Static RAM, designed to be used as a stand-alone 512K-bit Dual-Port RAM or as a combination MASTER/SLAVE Dual-Port RAM for 32-bit and wider word systems. Using the IDT MASTER/SLAVE Dual-Port RAM approach in 32bit or wider memory system applications results in full-speed, error-free operation without the need for additional discrete logic. The device provides two independent ports with separate control, address, and I/O pins that permit independent, asynchronous access for reads or writes to any location in memory. An automatic power down feature controlled by the chip enables (CE0 and CE1) permits the on-chip circuitry of each port to enter a very low standby power mode. Fabricated using IDT's CMOS high-performance technology, these devices typically operate on only 500mW of power. The IDT70V27 is packaged in a 100-pin Thin Quad Flatpack (TQFP), a 108-pin ceramic Pin Grid Array (PGA), and a 144-pin Fine Pitch BGA (fp BGA). Pin Configurations(1,2,3) INDEX A9L A10L A11L A12L A13L A14L NC NC NC LBL UBL CE0L CE1L SEML Vcc R/WL OEL GND GND I/O15L I/O14L I/O13L I/O12L I/O11L I/O10L 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 1 75 2 74 3 73 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 72 71 70 69 68 67 66 65 64 63 62 61 60 59 58 57 56 55 54 53 52 A8L A7L A6L A5L A4L A3L A2L A1L A0L NC INTL BUSYL GND M/S BUSYR INTR A0R A1R A2R A3R A4R A5R A6R A7R A8R IDT70V27PF PN100-1(4) 100-PIN TQFP TOP VIEW(5) 51 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 A9R A10R A11R A12R A13R A14R NC NC NC LBR UBR CE0R CE1R SEMR GND R/WR OER GND GND I/O15R I/O14R I/O13R I/O12R I/O11R I/O10R 3603 drw 02 NOTES: 1. All VCC pins must be connected to power supply. 2. All GND pins must be connected to ground supply. 3. Package body is approximately 14mm x 14mm x 1.4mm. 4. This package code is used to reference the package diagram. 5. This text does not indicate orientation of the actual part-marking. I/O9L I/O8L Vcc I/O7L I/O6L I/O5L I/O4L I/O3L I/O2L GND I/O1L I/O0L GND I/O0R I/O1R I/O2R I/O3R I/O4R I/O5R I/O6R Vcc I/O7R I/O8R I/O9R NC 2 IDT 70V27S/L High-Speed 3.3V 32K x 16 Dual-Port Static RAM Commercial and Industrial Temperature Range Pin Configurations(1,2,3) (con't.) A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A13 NC B1 NC B2 A8L B3 A5L B4 A1L B5 INTL B6 GND BUSYR A1R B7 B8 B9 A5R B10 NC B11 NC B12 NC B13 NC C1 NC C2 NC C3 A6L C4 A2L C5 NC C6 M/S C7 INTR C8 A2R C9 A6R C10 NC C11 NC C12 NC C13 A10L D1 A9L D2 NC D3 A7L D4 A3L D5 NC D6 NC D7 D8 NC A3R D9 A7R D10 A9R D11 A10R D12 A11R D13 A14L E1 A13L E2 A12L E3 A11L E4 A4L A0L BUSYL A0R A4R A8R E10 A12R E11 A13R E12 A14R E13 LBL F1 NC F2 F3 NC F4 NC UBL G4 NC F10 NC F11 NC F12 LBR F13 SEML CE1L G1 G2 CE0L G3 IDT70V27BF BF144-1(4) UBR G10 CE0R G11 CE1R SEMR G12 G13 VCC H1 VCC H2 VCC H3 H4 NC 144-Pin fpBGA Top View(5) NC H10 NC H11 GND H12 GND H13 NC J1 R/WL J2 J3 OEL J4 NC NC J10 OER J11 R/WR J12 GND J13 GND K1 I/O15L K2 I/O14L I/013L K3 K4 K5 K6 K7 K8 K9 I/O13R I/O14R I/O15R GND K10 K11 K12 K13 I/O12L L1 NC L2 L3 NC L4 NC I/O6L L5 I/O3L L6 I/O0R L7 I/O3R L8 I/O6R I/O11R L9 L10 NC L11 NC L12 I/O12R L13 , I/O11L I/O10L M1 M2 NC M3 NC M4 I/O5L M5 I/O2L M6 GND M7 VCC M8 I/O5R M9 NC M10 NC M11 NC M12 I/O10R M13 I/O9L N1 NC N2 NC N3 VCC N4 I/O4L N5 GND N6 I/O0L N7 I/O2R N8 I/O4R N9 I/O7R N10 I/O8R N11 NC N12 I/O9R N13 NC NC I/O8L I/O7L NC I/O1L VCC I/O1R NC VCC NC NC NC 3603 drw 02a NOTES: 1. All VCC pins must be connected to power supply. 2. All GND pins must be connected to ground supply. 3. Package body is approximately 12mm x 12mm x 1.4mm. 4. This package code is used to reference the package diagram. 5. This text does not indicate orientation of the actual part-marking. 3 IDT 70V27S/L High-Speed 3.3V 32K x 16 Dual-Port Static RAM Commercial and Industrial Temperature Range Pin Configurations(1,2,3) (con't.) 81 80 77 74 72 69 68 65 63 60 57 54 12 A10R 84 A11R 83 A14R 78 76 NC NC 79 UBR 73 SEMR 70 GND 67 GND 64 NC 61 I/O13R I/O10R 59 56 NC 53 11 A7R 87 A8R 86 A13R 82 LBR 75 CE1R R/WR 71 66 GND I/O14R I/O12R I/O9R 62 58 55 51 NC 50 10 09 08 A4R 90 A5R 88 A9R 85 A12R NC CE0R OER I/O15R I/O11R NC 52 I/O8R 49 I/O7R 47 A1R 92 A3R 91 A6R 89 NC 48 Vcc 46 I/O5R 45 INTR 95 A0R 94 A2R 93 I/O6R 44 I/O4R 43 I/O3R 42 07 06 GND 96 M/S BUSYR 97 98 IDT70V27G G108-1(4) 108-PIN PGA TOP VIEW (5) I/O2R 39 I/O1R 40 I/O0R 41 BUSYL INTL 99 100 NC 102 I/O1L 35 I/O0L 37 GND 38 05 04 A0L 101 A1L 103 A3L 106 I/O4L 31 I/O2L 34 GND 36 A2L 104 A4L 105 1 A7L 4 8 12 17 21 25 Vcc 28 I/O5L 32 I/O3L 33 03 A5L 107 2 A6L 5 A10L 7 A13L NC 10 CE1L 13 GND 16 I/O14L I/O10L 19 22 NC 24 I/O7L 29 I/O6L 30 02 A8L 108 3 A11L 6 A14L 9 NC LBL D UBL 11 SEML 14 OEL 15 GND I/O13L 18 20 I/O11L 23 26 NC I/O8L 27 01 A9L A A12L B NC C CE0L E Vcc F R/WL G NC H I/O15L J I/O12L K I/O9L L NC M 3603 drw 03 INDEX NOTES: 1. All VCC pins must be connected to power supply. 2. All GND pins must be connected to ground supply. 3. Package body is approximately 1.21in x 1.21in x .16in. 4. This package code is used to reference the package diagram. 5. This text does not indicate orientation of the actual part-marking. Pin Names Left Port CE0L, CE1L R/WL OEL A0L - A14L I/O0L - I/O15L SEML UBL LBL INTL BUSYL Right Port CE0R, CE1R R/WR OER A0R - A14R I/O0R - I/O15R SEMR UBR LBR INTR BUSYR M/S VCC GND Chip Enable Read/Write Enable Output Enable Address Data Input/Output Semaphore Enable Upper Byte Select Lower Byte Select Interrupt Flag Busy Flag Master or Slave Select Power Ground 3603 tbl 01 Names 4 IDT 70V27S/L High-Speed 3.3V 32K x 16 Dual-Port Static RAM Commercial and Industrial Temperature Range Truth Table I Chip Enable(1,2,3) CE CE0 VIL L < 0.2V VIH X H >VCC -0.2V X NOTES: CE1 VIH >VCC -0.2V X VIL X <0.2V Port Selected (TTL Active) Port Selected (CMOS Active) Port Deselected (TTL Inactive) Port Deselected (TTL Inactive) Mode Port Deselected (CMOS Inactive) Port Deselected (CMOS Inactive) 3603 tbl 02 1. Chip Enable references are shown above with the actual CE0 and CE1 levels, CE is a reference only. 2. Port "A" and "B" references are located where CE is used. 3. "H" = VIH and "L" = VIL Truth Table II Non-Contention Read/Write Control Inputs(1) CE (2) Outputs UB X H L H L L H L X LB X H H L L H L L X SEM H H H H H H H H X I/O8-15 High-Z High-Z DATAIN High-Z DATAIN DATAOUT High-Z DATAOUT High-Z I/O0-7 High-Z High-Z High-Z DATAIN DATAIN High-Z DATAOUT DATAOUT High-Z Mode Deselected: Power-Down Both Bytes Deselected Write to Upper Byte Only Write to Lower Byte Only Write to Both Bytes Read Upper Byte Only Read Lower Byte Only Read Both Bytes Outputs Disabled 3603 tbl 03 R/W X X L L L H H H X OE X X X X X L L L H H X L L L L L L X NOTES: 1. A0L -- A14L A0R -- A14R. 2. Refer to Chip Enable Truth Table. Truth Table III Semaphore Read/Write Control Inputs(1) CE (2) Outputs UB X H X H L X LB X H X H X L SEM L L L L L L I/O8-15 DATAOUT DATAOUT DATAIN DATAIN ______ ______ R/W H H OE L L X X X X I/O0-7 DATAOUT DATAOUT DATAIN DATAIN ______ ______ Mode Read Data in Semaphore Flag Read Data in Semaphore Flag Write I/O0 into Semaphore Flag Write I/O0 into Semaphore Flag Not Allowed Not Allowed 3603 tbl 04 H X H X L L X X NOTES: 1. There are eight semaphore flags written to I/O0 and read from all the I/Os (I/O0-I/O15). These eight semaphore flags are addressed by A0-A2. 2. Refer to Chip Enable Truth Table. 5 IDT 70V27S/L High-Speed 3.3V 32K x 16 Dual-Port Static RAM Commercial and Industrial Temperature Range Absolute Maximum Ratings(1) Symbol VTERM(2) Rating Terminal Voltage with Respect to GND Temperature Under Bias Storage Temperature DC Output Current Commercial & Industrial -0.5 to +4.6 Unit V Maximum Operating Temperature and Supply Voltage(1,2) Grade Commercial Ambient Temperature 0 C to +70 C -40 C to +85 C O O O O GND 0V 0V Vcc 3.3V + 0.3V 3.3V + 0.3V 3603 tbl 06 TBIAS TSTG IOUT -55 to +125 -65 to +150 50 o C C Industrial o NOTES: 1. This is the parameter TA. This is the "instant on" case temperature. 2. Industrial temperature: for specific speeds, packages and powers contact your sales office. mA 3603 tbl 05 NOTES: 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 this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability. 2. VTERM must not exceed Vcc + 0.3V for more than 25% of the cycle time or 10ns maximum, and is limited to < 20mA for the period of VTERM > Vcc + 0.3V. Recommended DC Operating Conditions(1) Symbol VCC GND VIH VIL Parameter Supply Voltage Ground Input High Voltage Input Low Voltage Min. 3.0 0 2.0 -0.3 (1) Typ. 3.3 0 ____ Max. 3.6 0 VCC+0.3V 0.8 (2) Unit V V V V 3603 tbl 07 ____ Capacitance(1) Symbol CIN COUT (TA = +25C, f = 1.0mhz)TQFP ONLY Parameter Input Capacitance Output Capacitance Conditions(2) VIN = 3dV VOUT = 3dV Max. 9 10 Unit pF pF 3603 tbl 08 NOTES: 1. VIL > -1.5V for pulse width less than 10ns. 2. VTERM must not exceed Vcc + 0.3V. NOTES: 1. This parameter is determined by device characterization but is not production tested. 2. 3dV represents the interpolated capacitance when the input and output signals switch from 0V to 3V or from 3V to 0V. DC Electrical Characteristics Over the Operating Temperature and Supply Voltage Range (VCC = 3.3V 0.3V) 70V27S Symbol |ILI| |ILO| VOL VOH NOTE: 1. At Vcc 70V27L Min. ___ Parameter Input Leakage Current(1) Output Leakage Current Output Low Voltage Output High Voltage Test Conditions VCC = 3.6V, VIN = 0V to VCC CE = VIH, VOUT = 0V to VCC IOL = 4mA IOH = -4mA Min. ___ Max. 10 10 0.4 ___ Max. 5 5 0.4 ___ Unit A A V V 3603 tbl 09 ___ ___ ___ ___ 2.4 2.4 < 2.0V, input leakages are undefined. 6 IDT 70V27S/L High-Speed 3.3V 32K x 16 Dual-Port Static RAM Commercial and Industrial Temperature Range DC Electrical Characteristics Over the Operating Temperature and Supply Voltage Range(1,6,7) (VCC = 3.3V 0.3V) 70V27X15 Com'l Only Symbol ICC Parameter Dynamic Operating Current (Both Ports Active) Test Condition CE = VIL, Outputs Disabled SEM = VIH f = fMAX(3) Version COM'L IND'L COM'L IND'L S L S L S L S L S L S L S L S L S L S L Typ. (2) 170 170 ____ ____ 70V27X20 Com'l Only Typ.(2) 165 165 ____ ____ 70V27X25 Com'l Only Typ. (2) 145 145 145 145 27 27 27 27 90 90 90 90 1.0 0.2 1.0 0.2 90 90 90 90 Max. 245 210 280 245 50 40 60 50 150 135 170 150 6 3 10 6 145 130 170 145 3603 tbl 10a Max. 260 225 ____ ____ Max. 255 220 ____ ____ Unit mA ISB1 Standby Current CEL = CER = VIH (Bo th Ports - TTL Level SEMR = SEML = VIH Inputs) f = fMAX(3) 44 44 ____ ____ 70 60 ____ ____ 39 39 ____ ____ 60 50 ____ ____ mA ISB2 Standby Current (One Port - TTL Level Inputs) CE"A" = VIL and CE"B" = VIH(5) Active Port Outputs Disabled, f=fMAX(3) SEMR = SEML = VIH Both Ports CEL and CER > VCC - 0.2V VIN > VCC - 0.2V or VIN < 0.2V, f = 0(4) SEMR = SEML > VCC - 0.2V CE"A" < 0.2V and CE"B" > VCC - 0.2V(5) SEMR = SEML > VCC - 0.2V VIN > VCC - 0.2V or VIN < 0.2V Active Port Outputs Disabled f = fMAX(3) COM'L 115 115 ____ ____ 160 145 ____ ____ 105 105 ____ ____ 155 140 ____ ____ mA IND'L ISB3 Full Standby Current (Both Ports - All CMOS Level Inputs) COM'L IND'L 1.0 0.2 ____ ____ 6 3 ____ ____ 1.0 0.2 ____ ____ 6 3 ____ ____ mA ISB4 Full Standby Current (One Port - All CMOS Level Inputs) COM'L IND'L 115 115 ____ ____ 155 140 ____ ____ 105 105 ____ ____ 150 135 ____ ____ mA NOTES: 1. 'X' in part numbers indicates power rating (S or L). 2. VCC = 3.3V, TA = +25C, and are not production tested. ICCDC = 90mA (Typ.) 3. At f = fMAX, address and control lines (except Output Enable) are cycling at the maximum frequency read cycle of 1/tRC, and using "AC Test Conditions" of input levels of GND to 3V. 4. f = 0 means no address or control lines change. 5. Port "A" may be either left or right port. Port "B" is the opposite from port "A". 6. Refer to Chip Enable Truth Table. 7. Industrial temperature: for other speeds, packages and powers contact your sales office. 7 IDT 70V27S/L High-Speed 3.3V 32K x 16 Dual-Port Static RAM Commercial and Industrial Temperature Range DC Electrical Characteristics Over the Operating Temperature and Supply Voltage Range(1,6,7) (VCC = 3.3V 0.3V) 70V27X35 Com'l & Ind Symbol ICC Parameter Dynamic Operating Current (Both Ports Active) Test Condition CE = VIL, Outputs Disabled SEM = VIH f = fMAX(3) Version COM'L IND'L COM'L IND'L S L S L S L S L S L S L S L S L S L S L Typ.(2) 135 135 135 135 22 22 22 22 85 85 85 85 1.0 0.2 1.0 0.2 85 85 85 85 Max. 235 190 270 235 45 35 55 45 140 125 160 140 6 3 10 6 135 120 160 135 70V27X55 Com'l Only Typ. (2) 125 125 125 125 15 15 15 15 75 75 75 75 1.0 0.2 1.0 0.2 75 75 75 75 Max. 225 180 260 225 40 30 50 40 140 125 160 140 6 3 10 6 135 120 160 135 3603 tbl 10b Unit mA ISB1 Standby Current (Bo th Ports - TTL Level Inputs) CEL = CER = VIH SEMR = SEML = VIH f = fMAX(3) mA ISB2 Standby Current (One Port - TTL Level Inputs) CE"A" = VIL and CE"B" = VIH(5) Active Port Outputs Disabled, f=fMAX(3) SEMR = SEML = VIH Both Ports CEL and CER > VCC - 0.2V VIN > VCC - 0.2V or VIN < 0.2V, f = 0(4) SEMR = SEML > VCC - 0.2V CE"A" < 0.2V and CE"B" > VCC - 0.2V(5) SEMR = SEML > VCC - 0.2V VIN > VCC - 0.2V or VIN < 0.2V Active Port Outputs Disabled f = fMAX(3) COM'L mA IND'L ISB3 Full Standby Current (Both Ports - All CMOS Level Inputs) COM'L IND'L mA ISB4 Full Standby Current (One Port - All CMOS Level Inputs) COM'L IND'L mA NOTES: 1. 'X' in part numbers indicates power rating (S or L). 2. VCC = 3.3V, TA = +25C, and are not production tested. ICCDC = 90mA (Typ.) 3. At f = fMAX, address and control lines (except Output Enable) are cycling at the maximum frequency read cycle of 1/tRC, and using "AC Test Conditions" of input levels of GND to 3V. 4. f = 0 means no address or control lines change. 5. Port "A" may be either left or right port. Port "B" is the opposite from port "A". 6. Refer to Chip Enable Truth Table. 7. Industrial temperature: for other speeds, packages and powers contact your sales office. AC Test Conditions Input Pulse Levels Input Rise/Fall Times Input Timing Reference Levels Output Reference Levels Output Load GND to 3.0V 5ns Max. 1.5V 1.5V Figures 1 and 2 3603 tbl 11 3.3V 3.3V 590 DATAOUT 590 DATAOUT BUSY INT 435 30pF 435 5pF* 3603 drw 04 Figure 1. AC Output Test Load Figure 2. Output Test Load (for tLZ, tHZ, tWZ, tOW) *Including scope and jig. 8 IDT 70V27S/L High-Speed 3.3V 32K x 16 Dual-Port Static RAM Commercial and Industrial Temperature Range AC Electrical Characteristics Over the Operating Temperature and Supply Voltage Range(4, 6) 70V27X15 Com'l Only Symbol READ CYCLE tRC tAA tACE tABE tAOE tOH tLZ tHZ tPU tPD tSOP tSAA Read Cycle Time Address Access Time Chip Enable Access Time (3) Byte Enable Access Time (3) Output Enable Access Time Output Hold from Address Change Output Low-Z Time (1,2) 70V27X20 Com'l Only Min. Max. 70V27X25 Com'l Only Min. Max. Unit Parameter Min. Max. 15 ____ ____ 20 ____ ____ 25 ____ ____ ns ns ns ns ns ns ns ns ns ns ns ns 3603 tbl 12a 15 15 15 10 ____ 20 20 20 12 ____ 25 25 25 15 ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ 3 3 ____ 3 3 ____ 3 3 ____ ____ ____ ____ Output High-Z Time (1,2) Chip Enable to Power Up Time (2,5) Chip Disable to Power Down Time (2,5) Semaphore Flag Update Pulse (OE or SEM) Semaphore Address Access Time 12 ____ 12 ____ 15 ____ 0 ____ 0 ____ 0 ____ 15 ____ 20 ____ 25 ____ 10 ____ 10 ____ 15 ____ 15 20 35 70V27X35 Com'l & Ind Symbol READ CYCLE tRC tAA tACE tABE tAOE tOH tLZ tHZ tPU tPD tSOP tSAA Read Cycle Time Address Access Time Chip Enable Access Time (3) Byte Enable Access Time (3) Output Enable Access Time Output Hold from Address Change Output Low-Z Time (1,2) 70V27X55 Com'l Only Min. Max. Unit Parameter Min. Max. 35 ____ ____ 55 ____ ____ ns ns ns ns ns ns ns ns ns ns ns ns 3603 tbl 12b 35 35 35 20 ____ 55 55 55 30 ____ ____ ____ ____ ____ ____ ____ 3 3 ____ 3 3 ____ ____ ____ Output High-Z Time (1,2) Chip Enable to Power Up Time (2,5) 20 ____ 25 ____ 0 ____ 0 ____ Chip Disable to Power Down Time (2,5) Semaphore Flag Update Pulse (OE or SEM) Semaphore Address Access Time 45 ____ 50 ____ 15 ____ 15 ____ 45 65 NOTES: 1. Transition is measured 0mV from Low or High-impedance voltage with Output Test Load (Figure 2). 2. This parameter is guaranteed by device characterization, but is not production tested. 3. To access RAM, CE = VIL and SEM = VIH. To access semaphore, CE= VIH and SEM = VIL. 4. 'X' in part numbers indicates power rating (S or L). 5. Refer to Chip Enable Truth Table. 6. Industrial temperature: for other speeds, packages and powers contact your sales office. 9 IDT 70V27S/L High-Speed 3.3V 32K x 16 Dual-Port Static RAM Commercial and Industrial Temperature Range Waveform of Read Cycles(5) tRC ADDR tAA tACE(4) tAOE(4) OE tABE (4) UB, LB (4) CE (6) R/W tLZ (1) DATAOUT VALID DATA (4) tOH tHZ(2) BUSYOUT tBDD (3,4) 3603 drw 05 Timing of Power-Up Power-Down CE ICC 50% 50% 3603 drw 06 (6) tPU ISB tPD , NOTES: 1. Timing depends on which signal is asserted last: CE, OE, LB, or UB. 2. Timing depends on which signal is de-asserted first: CE, OE, LB, or UB. 3. tBDD delay is required only in cases where the opposite port is completing a write operation to the same address location. For simultaneous read operations BUSY has no relation to valid output data. 4. Start of valid data depends on which timing becomes effective last tAOE, tACE, tAA or tBDD. 5. SEM = VIH. 6. Refer to Chip Enable Truth Table. 10 IDT 70V27S/L High-Speed 3.3V 32K x 16 Dual-Port Static RAM Commercial and Industrial Temperature Range AC Electrical Characteristics Over the Operating Temperature and Supply Voltage(5,6) 70V27X15 Com'l Only Symbol WRITE CYCLE tWC tEW tAW tAS tWP tWR tDW tHZ tDH tWZ tOW tSWRD tSPS Write Cycle Time Chip Enable to End-of-Write (3) 70V27X20 Com'l Only Min. Max. 70V27X25 Com'l Only Min. Max. Unit Parameter Min. Max. 15 12 12 0 12 0 10 ____ ____ 20 15 15 0 15 0 15 ____ ____ 25 20 20 0 20 0 15 ____ ____ ns ns ns ns ns ns ns ns ns ns ns ns ns 3603 tbl 13a ____ ____ ____ Address Valid to End-of-Write Address Set-up Time (3) Write Pulse Width Write Recovery Time Data Valid to End-of-Write Output High-Z Time Data Hold Time (4) (1,2) ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ 10 ____ 10 ____ 15 ____ 0 ____ 0 ____ 0 ____ Write Enable to Output in High-Z (1,2) Output Active from End-of-Write SEM Flag Write to Read Time SEM Flag Contention Window (1,2,4) 10 ____ 10 ____ 15 ____ 0 5 5 0 5 5 0 5 5 ____ ____ ____ ____ ____ ____ 70V27X35 Com'l & Ind Symbol WRITE CYCLE tWC tEW tAW tAS tWP tWR tDW tHZ tDH tWZ tOW tSWRD tSPS Write Cycle Time Chip Enable to End-of-Write (3) 70V27X55 Com'l Only Min. Max. Unit Parameter Min. Max. 35 30 30 0 25 0 20 ____ ____ 55 45 45 0 40 0 30 ____ ____ ns ns ns ns ns ns ns ns ns ns ns ns ns 3603 tbl 13b ____ ____ Address Valid to End-of-Write Address Set-up Time (3) Write Pulse Width Write Recovery Time Data Valid to End-of-Write Output High-Z Time Data Hold Time (4) (1,2) ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ 20 ____ 25 ____ 0 ____ 0 ____ Write Enable to Output in High-Z (1,2) Output Active from End-of-Write SEM Flag Write to Read Time SEM Flag Contention Window (1,2,4) 20 ____ 25 ____ 0 5 5 0 5 5 ____ ____ ____ ____ NOTES: 1. Transition is measured 0mV from Low or High-impedance voltage with Output Test Load (Figure 2). 2. This parameter is guaranteed by device characterization, but is not production tested. 3. To access RAM CE= VIL and SEM = VIH. To access semaphore, CE = VIH and SEM = VIL. Either condition must be valid for the entire tEW time. Refer to Chip Enable Truth Table. 4. The specification for tDH must be met by the device supplying write data to the RAM under all operating conditions. Although tDH and tOW values will vary over voltage and temperature, the actual tDH will always be smaller than the actual tOW. 5. 'X' in part numbers indicates power rating (S or L). 6. Industrial temperature: for other speeds, packages and powers contact your sales office. 11 IDT 70V27S/L High-Speed 3.3V 32K x 16 Dual-Port Static RAM Timing Waveform of Write Cycle No. 1, R/W Controlled Timing tWC ADDRESS tHZ OE tAW CE or SEM (9,10) (7) Commercial and Industrial Temperature Range (1,5,8) UB or LB (9) (3) tAS(6) R/W tWZ (7) DATAOUT (4) tWP (2) tWR tOW (4) tDW DATAIN tDH 3603 drw 07 Timing Waveform of Write Cycle No. 2, CE, UB, LB Controlled Timing(1,5) tWC ADDRESS tAW CE or SEM (9,10) tAS(6) UB or LB (9) tEW(2) tWR(3) R/W tDW DATAIN 3603 drw 08 tDH NOTES: 1. R/W or CE or UB and LB must be HIGH during all address transitions. 2. A write occurs during the overlap (tEW or tWP) of a LOW CE and a LOW R/W for memory array writing cycle. 3. tWR is measured from the earlier of CE or R/W (or SEM or R/W) going HIGH to the end of write cycle. 4. During this period, the I/O pins are in the output state and input signals must not be applied. 5. If the CE or SEM LOW transition occurs simultaneously with or after the R/W LOW transition, the outputs remain in the High-impedance state. 6. Timing depends on which enable signal is asserted last, CE or R/W. 7. This parameter is guaranteed by device characterization, but is not production tested. Transition is measured 0mV from steady state with the Output Test Load (Figure 2). 8. If OE is LOW during R/W controlled write cycle, the write pulse width must be the larger of tWP or (tWZ + tDW) to allow the I/O drivers to turn off and data to be placed on the bus for the required tDW. If OE is HIGH during an R/W controlled write cycle, this requirement does not apply and the write pulse can be as short as the specified tWP. 9. To access RAM, CE = VIL and SEM = VIH. To access semaphore, CE = VIH and SEM = VIL. tEW must be met for either condition. 10. Refer to Chip Enable Truth Table. 12 IDT 70V27S/L High-Speed 3.3V 32K x 16 Dual-Port Static RAM Timing Waveform of Semaphore Read after Write Timing, Either Side tSAA A0-A2 VALID ADDRESS tAW SEM tEW tDW I/O tAS R/W tSWRD OE Write Cycle Read Cycle 3603 drw 09 Commercial and Industrial Temperature Range (1) VALID ADDRESS tACE tSOP tOH DATAOUT(2) VALID tWR DATA IN VALID tWP tDH tAOE NOTES: 1. CE = VIH or UB and LB = VIH for the duration of the above timing (both write and read cycle), refer to Chip Enable Truth Table. 2. "DATAOUT VALID" represents all I/O's (I/O0-I/O15) equal to the semaphore value. Timing Waveform of Semaphore Write Contention(1,3,4) A0"A"-A2"A" MATCH SIDE (2) "A" R/W"A" SEM"A" tSPS A0"B"-A2"B" MATCH SIDE (2) "B" R/W"B" SEM"B" 3603 drw 10 NOTES: 1. DOR = DOL = VIL, CER = CEL = VIH, or both UB & LB = VIH (refer to Chip Enable Truth Table). 2. All timing is the same for left and right ports. Port "A" may be either left or right port. Port "B" is the opposite from port "A". 3. This parameter is measured from R/W"A" or SEM"A" going HIGH to R/W"B" or SEM"B" going HIGH. 4. If tSPS is not satisfied, there is no guarantee which side will be granted the semaphore flag. 13 IDT 70V27S/L High-Speed 3.3V 32K x 16 Dual-Port Static RAM Commercial and Industrial Temperature Range AC Electrical Characteristics Over the Operating Temperature and Supply Voltage Range(6,7) 70V27X15 Com'l Only Symbol BUSY TIMING (M/S=VIH) tBAA tBDA tBAC tBDC tAPS tBDD tWH BUSY Access Time from Address Match BUSY Disable Time from Address Not Matched BUSY Access Time from Chip Enable Low BUSY Disable Time from Chip Enable High Arbitration Priority Set-up Time BUSY Disable to Valid Data Write Hold After BUSY(5) (3) (2) ____ 70V27X20 Com'l Only Min. Max. 70V27X25 Com'l Only Min. Max. Unit Parameter Min. Max. 15 15 15 15 ____ ____ 20 20 20 20 ____ ____ 25 25 25 25 ____ ns ns ns ns ns ns ns ____ ____ ____ ____ ____ ____ ____ ____ ____ 5 ____ 5 ____ 5 ____ 17 ____ 35 ____ 35 ____ 12 15 20 BUSY TIMING (M/S=VIL) tWB tWH BUSY Input to Write (4) Write Hold After BUSY (5) 0 12 ____ 0 15 ____ 0 20 ____ ns ns ____ ____ ____ PORT-TO-PORT DELAY TIMING tWDD tDDD Write Pulse to Data Delay(1) Write Data Valid to Read Data Delay (1) ____ 30 25 ____ 45 30 ____ 55 50 ns ns 3603 tbl 14a ____ ____ ____ 70V27X35 Com'l & Ind Symbol BUSY TIMING (M/S=VIH) tBAA tBDA tBAC tBDC tAPS tBDD tWH BUSY Access Time from Address Match BUSY Disable Time from Address Not Matched BUSY Access Time from Chip Enable Low BUSY Disable Time from Chip Enable High Arbitration Priority Set-up Time (2) BUSY Disable to Valid Data(3) Write Hold After BUSY(5) ____ 70V27X55 Com'l Only Min. Max. Unit Parameter Min. Max. 35 35 35 35 ____ ____ 45 45 45 45 ____ ns ns ns ns ns ns ns ____ ____ ____ ____ ____ ____ 5 ____ 5 ____ 40 ____ 50 ____ 25 25 BUSY TIMING (M/S=VIL) tWB tWH BUSY Input to Write (4) Write Hold After BUSY(5) 0 25 ____ 0 25 ____ ns ns ____ ____ PORT-TO-PORT DELAY TIMING tWDD tDDD Write Pulse to Data Delay(1) Write Data Valid to Read Data Delay (1) ____ 65 60 ____ 85 80 ns ns 3603 tbl 14b ____ ____ NOTES: 1. Port-to-port delay through RAM cells from writing port to reading port, refer to "Timing Waveform of Write with Port-to-Port Read and BUSY (M/S = VIH)". 2. To ensure that the earlier of the two ports wins. 3. tBDD is a calculated parameter and is the greater of 0, tWDD - tWP (actual), or tDDD - tDW (actual). 4. To ensure that the write cycle is inhibited on port "B" during contention on port "A". 5. To ensure that a write cycle is completed on port "B" after contention on port "A". 6. 'X' in part numbers indicates power rating (S or L). 7. Industrial temperature: for other speeds, packages and powers contact your sales office. 14 IDT 70V27S/L High-Speed 3.3V 32K x 16 Dual-Port Static RAM Timing Waveform of Write with Port-to-Port Read and BUSY tWC ADDR"A" MATCH tWP R/W"A" tDW DATAIN "A" tAPS ADDR"B" tBAA BUSY"B" tWDD DATAOUT "B" tDDD (3) (1) Commercial and Industrial Temperature Range (2,5) (4) (M/S = VIH) tDH VALID MATCH tBDA tBDD VALID NOTES: 1. To ensure that the earlier of the two ports wins. tAPS is ignored for M/S = VIL (SLAVE). 2. CEL = CER = VIL (refer to Chip Enable Truth Table). 3. OE = VIL for the reading port. 4. If M/S = VIL (SLAVE), then BUSY is an input. Then for this example BUSY "A"= VIH and BUSY "B"= input is shown above. 5. All timing is the same for left and right ports. Port "A" may be either the left or right port. Port "B" is the port opposite from port "A". 3603 drw 11 Timing Waveform Write with BUSY (M/S = VIL) tWP R/W"A" tWB BUSY"B" tWH (3) (1) R/W"B" NOTES: 1. tWH must be met for both BUSY input (SLAVE) and output (MASTER). 2. BUSY is asserted on port "B" blocking R/W"B", until BUSY"B" goes HIGH. 3. tWB is only for the "Slave" version. (2) , 3603 drw 12 , 15 IDT 70V27S/L High-Speed 3.3V 32K x 16 Dual-Port Static RAM Waveform of BUSY Arbitration Controlled by CE Timing (M/S = VIH) ADDR"A" and "B" CE"A" tAPS (2) CE"B" tBAC BUSY"B" tBDC ADDRESSES MATCH Commercial and Industrial Temperature Range (1,3) 3603 drw 13 Waveform of BUSY Arbitration Cycle Controlled by Address Match Timing (M/S = VIH)(1) ADDR"A" tAPS(2) ADDR"B" tBAA BUSY"B" 3603 drw 14 ADDRESS "N" MATCHING ADDRESS "N" tBDA NOTES: 1. All timing is the same for left and right ports. Port "A" may be either the left or right port. Port "B" is the port opposite from port "A". 2. If tAPS is not satisfied, the busy signal will be asserted on one side or another but there is no guarantee on which side busy will be asserted. 3. Refer to Chip Enable Truth Table. AC Electrical Characteristics Over the Operating Temperature and Supply Voltage Range(1,2) 70V27X15 Com'l Only Symbol INTERRUPT TIMING tAS tWR tINS tINR Address Set-up Time Write Recovery Time Interrupt Set Time Interrupt Reset Time 0 0 ____ ____ ____ ____ 70V27X20 Com'l Only Min. Max. 70V27X25 Com'l Only Min. Max. Unit Parameter Min. Max. 0 0 ____ ____ ____ ____ 0 0 ____ ____ ____ ____ ns ns ns ns 3603 tbl 15a 15 25 20 20 25 35 70V27X35 Com'l &Ind Symbol INTERRUPT TIMING tAS tWR tINS tINR Address Set-up Time Write Recovery Time Interrupt Set Time Interrupt Reset Time 0 0 ____ ____ ____ ____ 70V27X55 Com'l Only Min. Max. Unit Parameter Min. Max. 0 0 ____ ____ ____ ____ ns ns ns ns 3603 tbl 15b 30 35 40 45 NOTES: 1. 'X' in part numbers indicates power rating (S or L). 2. Industrial temperature: for other speeds, packages and powers contact your sales office. 16 IDT 70V27S/L High-Speed 3.3V 32K x 16 Dual-Port Static RAM Commercial and Industrial Temperature Range Waveform of Interrupt Timing ADDR"A" tAS CE"A" (3) (1,5) tWC INTERRUPT SET ADDRESS (2) (4) tWR R/W"A" tINS (3) INT"B" 3603 drw 15 tRC ADDR"B" tAS CE"B" (3) INTERRUPT CLEAR ADDRESS (2) OE"B" tINR INT"B" 3603 drw 16 (3) NOTES: 1. All timing is the same for left and right ports. Port "A" may be either the left or right port. Port "B" is the port opposite from port "A". 2. See Interrupt Truth Table. 3. Timing depends on which enable signal (CE or R/W) is asserted last. 4. Timing depends on which enable signal (CE or R/W) is de-asserted first. 5. Refer to Chip Enable Truth Table. Truth Table IV Interrupt Flag(1,4) Left Port R/WL L X X X CEL L X X L OEL X X X L A14L-A0L 7FFF X X 7FFE INTL X X L (3) Right Port R/WR X X L X CER X L L X OER X L X X A14R-A0R X 7FFF 7FFE X INTR L(2) H(3) X X Function Set Right INTR Flag Reset Right INTR Flag Set Left INTL Flag Reset Left INTL Flag 3603 tbl 16 H(2) NOTES: 1. Assumes BUSYL = BUSYR =VIH. 2. If BUSYL = VIL, then no change. 3. If BUSYR = VIL, then no change. 4. Refer to Chip Enable Truth Table. 17 IDT 70V27S/L High-Speed 3.3V 32K x 16 Dual-Port Static RAM Truth Table V Address BUSY Arbritration Inputs CEL X H X L CER X X H L A0L-A14L A0R-A14R NO MATCH MATCH MATCH MATCH Outputs BUSYL(1) H H H (2) BUSYR(1) H H H (2) Function Normal Normal Normal Write Inhibit(3) 3603 tbl 17 Commercial and Industrial Temperature Range (4) NOTES: 1. Pins BUSYL and BUSYR are both outputs when the part is configured as a master. Both are inputs when configured as a slave. BUSY outputs on the IDT70V27 are push-pull, not open drain outputs. On slaves the BUSY input internally inhibits writes. 2. "L" if the inputs to the opposite port were stable prior to the address and enable inputs of this port. "H" if the inputs to the opposite port became stable after the address and enable inputs of this port. If tAPS is not met, either BUSYL or BUSYR = LOW will result. BUSYL and BUSYR outputs can not be LOW simultaneously. 3. Writes to the left port are internally ignored when BUSYL outputs are driving LOW regardless of actual logic level on the pin. Writes to the right port are internally ignored when BUSYR outputs are driving LOW regardless of actual logic level on the pin. 4. Refer to Chip Enable Truth Table. Truth Table VI Example of Semaphore Procurement Sequence(1,2) Functions No Action Left Port Writes "0" to Semaphore Right Port Writes "0" to Semaphore Left Port Writes "1" to Semaphore Left Port Writes "0" to Semaphore Right Port Writes "1" to Semaphore Left Port Writes "1" to Semaphore Right Port Writes "0" to Semaphore Right Port Writes "1" to Semaphore Left Port Writes "0" to Semaphore Left Port Writes "1" to Semaphore D0 - D15 Left 1 0 0 1 1 0 1 1 1 0 1 D0 - D15 Right 1 1 1 0 0 1 1 0 1 1 1 Semaphore free Left port has semaphore token No change. Right side has no write access to semaphore Right port obtains semaphore token No change. Left port has no write access to semaphore Left port obtains semaphore token Semaphore free Right port has semaphore token Semaphore free Left port has semaphore token Semaphore free 3603 tbl 18 Status NOTES: 1. This table denotes a sequence of events for only one of the eight semaphores on the IDT70V27. 2. There are eight semaphore flags written to via I/O0 and read from all the I/O's (I/O0-I/O15). These eight semaphores are addressed by A0 - A2. Functional Description The IDT70V27 provides two ports with separate control, address and I/O pins that permit independent access for reads or writes to any location in memory. The IDT70V27 has an automatic power down feature controlled by CE0 and CE1. The CE0 and CE1 control the on-chip power down circuitry that permits the respective port to go into a standby mode when not selected (CE HIGH). When a port is enabled, access to the entire memory array is permitted. 7FFE when CEL = OEL = VIL, R/W is a "don't care". Likewise, the right port interrupt flag (INTR) is asserted when the left port writes to memory location 7FFF (HEX) and to clear the interrupt flag (INTR), the right port must read the memory location 7FFF. The message (16 bits) at 7FFE or 7FFF is user-defined since it is an addressable SRAM location. If the interrupt func-tion is not used, address locations 7FFE and 7FFF are not used as mail boxes, but as part of the random access memory. Refer to Truth Table IV for the interrupt operation. Interrupts If the user chooses the interrupt function, a memory location (mail box or message center) is assigned to each port. The left port interrupt flag (INTL) is asserted when the right port writes to memory location 7FFE (HEX), where a write is defined as CER = R/WR = VIL per the Truth Table IV. The left port clears the interrupt through access of address location 18 Busy Logic Busy Logic provides a hardware indication that both ports of the RAM have accessed the same location at the same time. It also allows one of the two accesses to proceed and signals the other side that the RAM is "Busy". The BUSY pin can then be used to stall the access until the operation on IDT 70V27S/L High-Speed 3.3V 32K x 16 Dual-Port Static RAM Commercial and Industrial Temperature Range the other side is completed. If a write operation has been attempted from the side that receives a BUSY indication, the write signal is gated internally to prevent the write from proceeding. The use of BUSY logic is not required or desirable for all applications. In some cases it may be useful to logically OR the BUSY outputs together and use any BUSY indication as an interrupt source to flag the event of an illegal or illogical operation. If the write inhibit function of BUSY logic is not desirable, the BUSY logic can be disabled by placing the part in slave mode with the M/S pin. Once in slave mode the BUSY pin operates solely as a write inhibit input pin. Normal operation can be programmed by tying the BUSY pins HIGH. If desired, unintended write operations can be prevented to a port by tying the BUSY pin for that port LOW. The BUSY outputs on the IDT 70V27 RAM in master mode, are pushpull type outputs and do not require pull up resistors to operate. If these RAMs are being expanded in depth, then the BUSY indication for the resulting array requires the use of an external AND gate. Width Expansion with BUSY Logic Master/Slave Arrays A15 CE0 MASTER Dual Port RAM BUSYL BUSYR CE0 SLAVE Dual Port RAM BUSYL BUSYR When expanding an IDT70V27 RAM array in width while using BUSY CE1 MASTER Dual Port RAM BUSYL BUSYL BUSYR CE1 SLAVE Dual Port RAM BUSYL BUSYR BUSYR 3603 drw 17 Figure 3. Busy and chip enable routing for both width and depth expansion with IDT70V27 RAMs. logic, one master part is used to decide which side of the RAM array will receive a BUSY indication, and to output that indication. Any number of slaves to be addressed in the same address range as the master, use the busy signal as a write inhibit signal. Thus on the IDT70V27 RAM the BUSY pin is an output if the part is used as a master (M/S pin = VIH), and the BUSY pin is an input if the part is used as a slave (M/S pin = VIL) as shown in Figure 3. If two or more master parts were used when expanding in width, a split decision could result with one master indicating BUSY on one side of the array and another master indicating BUSY on one other side of the array. This would inhibit the write operations from one port for part of a word and inhibit the write operations from the other port for the other part of the word. The BUSY arbitration, on a master, is based on the chip enable and address signals only. It ignores whether an access is a read or write. In a master/slave array, both address and chip enable must be valid long enough for a BUSY flag to be output from the master before the actual write pulse can be initiated with either the R/W signal or the byte enables. Failure to observe this timing can result in a glitched internal write inhibit signal and corrupted data in the slave. an additional 8 address locations dedicated to binary semaphore flags. These flags allow either processor on the left or right side of the Dual-Port RAM to claim a privilege over the other processor for functions defined by the system designer's software. As an example, the semaphore can be used by one processor to inhibit the other from accessing a portion of the Dual-Port RAM or any other shared resource. The Dual-Port RAM features a fast access time, and both ports are completely independent of each other. This means that the activity on the left port in no way slows the access time of the right port. Both ports are identical in function to standard CMOS Static RAM and can be read from, or written to, at the same time with the only possible conflict arising from the simultaneous writing of, or a simultaneous READ/WRITE of, a nonsemaphore location. Semaphores are protected against such ambiguous situations and may be used by the system program to avoid any conflicts in the non-semaphore portion of the Dual-Port RAM. These devices have an automatic power-down feature controlled by CE the Dual-Port RAM enable, and SEM, the semaphore enable. The CE and SEM pins control on-chip power down circuitry that permits the respective port to go into standby mode when not selected. This is the condition which is shown in Truth Table II where CE and SEM are both HIGH. Systems which can best use the IDT70V27 contain multiple processors or controllers and are typically very high-speed systems which are software controlled or software intensive. These systems can benefit from a performance increase offered by the IDT70V27's hardware semaphores, which provide a lockout mechanism without requiring complex programming. Software handshaking between processors offers the maximum in system flexibility by permitting shared resources to be allocated in varying configurations. The IDT70V27 does not use its semaphore flags to control any resources through hardware, thus allowing the system designer total flexibility in system architecture. An advantage of using semaphores rather than the more common methods of hardware arbitration is that wait states are never incurred in either processor. This can prove to be a major advantage in very highspeed systems. How the Semaphore Flags Work The semaphore logic is a set of eight latches which are independent of the Dual-Port RAM. These latches can be used to pass a flag, or token, from one port to the other to indicate that a shared resource is in use. The semaphores provide a hardware assist for a use assignment method called "Token Passing Allocation." In this method, the state of a semaphore latch is used as a token indicating that shared resource is in use. If the left processor wants to use this resource, it requests the token by setting the latch. This processor then verifies its success in setting the latch by reading it. If it was successful, it proceeds to assume control over the shared resource. If it was not successful in setting the latch, it determines that the right side processor has set the latch first, has the token and is using the shared resource. The left processor can then either repeatedly request that semaphore's status or remove its request for that semaphore to perform another task and occasionally attempt again to gain control of the token via the set and test sequence. Once the right side has relinquished the token, the left side should succeed in gaining control. The semaphore flags are active low. A token is requested by writing a zero into a semaphore latch and is released when the same side writes 19 Semaphores The IDT70V27 is a fast Dual-Port 32K x 16 CMOS Static RAM with IDT 70V27S/L High-Speed 3.3V 32K x 16 Dual-Port Static RAM Commercial and Industrial Temperature Range a one to that latch. The eight semaphore flags reside within the IDT70V27 in a separate memory space from the Dual-Port RAM. This address space is accessed by placing a low input on the SEM pin (which acts as a chip select for the semaphore flags) and using the other control pins (Address, OE, and R/W) as they would be used in accessing a standard Static RAM. Each of the flags has a unique address which can be accessed by either side through address pins A0 - A2. When accessing the semaphores, none of the other address pins has any effect. When writing to a semaphore, only data pin D0 is used. If a low level is written into an unused semaphore location, that flag will be set to a zero on that side and a one on the other side (see Table VI). That semaphore can now only be modified by the side showing the zero. When a one is written into the same location from the same side, the flag will be set to a one for both sides (unless a semaphore request from the other side is pending) and then can be written to by both sides. The fact that the side which is able to write a zero into a semaphore subsequently locks out writes from the other side is what makes semaphore flags useful in interprocessor communications. (A thorough discussion on the use of this feature follows shortly.) A zero written into the same location from the other side will be stored in the semaphore request latch for that side until the semaphore is freed by the first side. When a semaphore flag is read, its value is spread into all data bits so that a flag that is a one reads as a one in all data bits and a flag containing a zero reads as all zeros. The read value is latched into one side's output register when that side's semaphore select (SEM) and output enable (OE) signals go active. This serves to disallow the semaphore from changing state in the middle of a read cycle due to a write cycle from the other side. Because of this latch, a repeated read of a semaphore in a test loop must cause either signal (SEM or OE) to go inactive or the output will never change. A sequence WRITE/READ must be used by the semaphore in order to guarantee that no system level contention will occur. A processor requests access to shared resources by attempting to write a zero into a semaphore location. If the semaphore is already in use, the semaphore request latch will contain a zero, yet the semaphore flag will appear as a one, a fact which the processor will verify by the subsequent read (see Table VI). As an example, assume a processor writes a zero to the left port at a free semaphore location. On a subsequent read, the processor will verify that it has written successfully to that location and will assume control over the resource in question. Meanwhile, if a processor on the right side attempts to write a zero to the same semaphore flag it will fail, as will be verified by the fact that a one will be read from that semaphore on the right side during the subsequent read. Had a sequence of READ/WRITE been used instead, system contention problems could have occurred during the gap between the read and write cycles. It is important to note that a failed semaphore request must be followed by either repeated reads or by writing a one into the same location. The reason for this is easily understood by looking at the simple logic diagram of the semaphore flag in Figure 4. Two semaphore request latches feed L PORT SEMAPHORE REQUEST FLIP FLOP D0 WRITE D Q R PORT SEMAPHORE REQUEST FLIP FLOP Q D D0 WRITE SEMAPHORE READ SEMAPHORE READ Figure 4. IDT70V27 Semaphore Logic 3603 drw 18 into a semaphore flag. Whichever latch is first to present a zero to the semaphore flag will force its side of the semaphore flag low and the other side high. This condition will continue until a one is written to the same semaphore request latch. Should the other side's semaphore request latch have been written to a zero in the meantime, the semaphore flag will flip over to the other side as soon as a one is written into the first side's request latch. The second side's flag will now stay low until its semaphore request latch is written to a one. From this it is easy to understand that, if a semaphore is requested and the processor which requested it no longer needs the resource, the entire system can hang up until a one is written into that semaphore request latch. The critical case of semaphore timing is when both sides request a single token by attempting to write a zero into it at the same time. The semaphore logic is specially designed to resolve this problem. If simultaneous requests are made, the logic guarantees that only one side receives the token. If one side is earlier than the other in making the request, the first side to make the request will receive the token. If both requests arrive at the same time, the assignment will be arbitrarily made to one port or the other. One caution that should be noted when using semaphores is that semaphores alone do not guarantee that access to a resource is secure. As with any powerful programming technique, if semaphores are misused or misinterpreted, a software error can easily happen. Initialization of the semaphores is not automatic and must be handled via the initialization program at power-up. Since any semaphore request flag which contains a zero must be reset to a one, all semaphores on both sides should have a one written into them at initialization from both sides to assure that they will be free when needed. 20 IDT 70V27S/L High-Speed 3.3V 32K x 16 Dual-Port Static RAM Commercial and Industrial Temperature Range Ordering Information IDT XXXXX Device Type A Power 999 Speed A Package A Process/ Temperature Range Blank I(1) Commercial (0C to +70C) Industrial (-40C to +85C) BF PF G 15 20 25 35 55 S L 70V27 NOTE: 1. Industrial temperature range is available on selected TQFP packages in low power. For other speeds, packages and powers contact your sales office. 144-pin fpBGA (BF144-1) 100-pin TQFP (PN100-1) 108-pin PGA (G108-1) Commercial Commercial Commercial Commercial & Industrial Commercial Standard Power Low Power 512K (32K x 16) 3.3V Dual-Port RAM 3603 drw 19 Speed in nanoseconds Preliminary Datasheet: "PRELIMINARY' datasheets contain descriptions for products that are in early release. 21 IDT 70V27S/L High-Speed 3.3V 32K x 16 Dual-Port Static RAM Commercial and Industrial Temperature Range Datasheet Document History 12/3/98: Initiated Document History Converted to new format Typographical and cosmetic changes Added fpBGA information Added 15ns and 20ns speed grades Updated DC Electrical Characteristics Added additional notes to pin configurations Page 5 Fixed typo in Table III Page 3 Changed package body height from 1.1mm to 1.4mm Page 1 Changed 660mW to 660W Replaced IDT logo Page 2 Made pin correction Changed 200mV to 0mV in notes Page 1 Fixed page numbering; copywright Page 6 Increated storage temperature parameter Clarified TA Parameter Page 7 and8 DC Electrical parameters-changed wording from "open" to "disabled" Removed Preliminary status 4/2/99: 8/1/99: 8/30/99: 4/25/00: 1/12/01: CORPORATE HEADQUARTERS 2975 Stender Way Santa Clara, CA 95054 for SALES: 800-345-7015 or 408-727-5116 fax: 408-492-8674 www.idt.com for Tech Support: 831-754-4613 DualPortHelp@idt.com The IDT logo is a registered trademark of Integrated Device Technology, Inc. 22 |
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