HIGH-SPEED 3.3V 64K x 18 DUAL-PORT STATIC RAM Features ◆ ◆ ◆ ◆ ◆ True Dual-Ported memory cells which allow simultaneous access of the same memory location High-speed access – Commercial: 15/20ns (max.) – Industrial: 20ns (max.) Low-power operation – IDT70V38L Active: 440mW (typ.) Standby: 660µW (typ.) Dual chip enables allow for depth expansion without external logic IDT70V38 easily expands data bus width to 36 bits or more using the Master/Slave select when cascading more than one device ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆ ◆ IDT70V38L 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 Separate upper-byte and lower-byte controls for multiplexed bus and bus matching compatibility LVTTL-compatible, single 3.3V (±0.3V) power supply Available in a 100-pin TQFP Industrial temperature range (–40°C to +85°C) is available for selected speeds Functional Block Diagram R/WL UBL R/WR UBR CE0L CE1L CE0R CE1R OEL OER LBL LBR I/O9-17R I/O 9-17L I/O Control I/O 0-8L I/O Control I/O0-8R BUSYL (1,2) A15L BUSYR 64Kx18 MEMORY ARRAY 70V38 Address Decoder A0L 16 CE0L CE1L OEL R/WL . A15R A0R 16 ARBITRATION INTERRUPT SEMAPHORE LOGIC SEML (2) INT L Address Decoder (1,2) M/S NOTES: 1. BUSY is an input as a Slave (M/S=VIL) and an output when it is a Master (M/S=VIH). 2. BUSY and INT are non-tri-state totem-pole outputs (push-pull). (1) CE0R CE1R OER R/WR SEMR (2) INTR 4850 drw 01 SEPTEMBER 2003 1 ©2003 Integrated Device Technology, Inc. DSC-4850/3 IDT70V38L High-Speed 3.3V 64K x 18 Dual-Port Static RAM Industrial and Commercial Temperature Ranges Description The IDT70V38 is a high-speed 64K x 18 Dual-Port Static RAM. The IDT70V38 is designed to be used as a stand-alone 1152K-bit Dual-Port RAM or as a combination MASTER/SLAVE Dual-Port RAM for 36-bit-or-more word system. Using the IDT MASTER/SLAVE Dual-Port RAM approach in 36-bit or wider memory system applications results in full-speed, error-free operation without the need for additional discrete logic. This 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 (either CE0 or CE1) permit 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 440mW of power. The IDT70V38 is packaged in a 100-pin Thin Quad Flatpack (TQFP). A8L A7L A6L A5L A4L A3L A2L A1L A0L INTL BUSYL GND GND Vcc M/S BUSYR INTR A0R A1R A2R A3R A4R A5R A6R A7R Pin Configurations(1,2,3) INDEX 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 72 5 71 6 70 7 69 8 68 9 IDT70V38PF PN100-1(4) 10 11 12 100-Pin TQFP Top View(5) 13 14 67 66 65 64 63 62 15 61 16 60 17 59 18 58 19 57 56 20 22 55 54 23 53 21 52 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 24 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 I/O10R A9L A10L A11L A12L A13L A14L A15L LBL UBL CE0L CE1L SEML R/WL OEL Vcc GND I/O17L I/O16L GND I/O15L I/O14L I/O13L I/O12L I/O11L I/O10L NOTES: 1. All Vcc pins must be connected to power supply. 2. All GND pins must be connected to ground. 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. 2 A8R A9R A10R A11R A12R A13R A14R A15R LBR UBR CE0R CE1R SEMR R/WR GND OER GND I/O17R GND I/O16R I/O15R I/O14R I/O13R I/O12R I/O11R 4850 drw 02 . IDT70V38L High-Speed 3.3V 64K x 18 Dual-Port Static RAM Industrial and Commercial Temperature Ranges Pin Names Left Port Right Port Names CE0L, CE1L CE0R, CE1R Chip Enables R/WL R/WR Read/Write Enable OEL OER Output Enable A0L - A15L A0R - A15R Address I/O0L - I/O17L I/O0R - I/O17R Data Input/Output SEML SEMR Semaphore Enable UBL UBR Upper Byte Select LBL LBR Lower Byte Select INTL INTR Interrupt Flag BUSYL BUSYR Busy Flag M/S Master or Slave Select VCC Power GND Ground 4850 tbl 01 Absolute Maximum Ratings(1) Symbol Rating Commercial & Industrial Unit VTERM(2) Terminal Voltage with Respect to GND -0.5 to +4.6 V TBIAS Temperature Under Bias -55 to +125 o TSTG Storage Temperature IOUT DC Output Current Recommended DC Operating Conditions Symbol -65 to +150 o 50 C V CC Supply Voltage GND Ground VIH Input High Voltage VIL C Parameter Input Low Voltage Min. Typ. Max. Unit 3.0 3.3 3.6 V 0 0 0 2.0 ____ (1) -0.3 V VCC+0.3 ____ (2) 0.8 V 4850 tbl 04 NOTES: 1. VIL > -1.5V for pulse width less than 10ns. 2. VTERM must not exceed Vcc + 0.3V. mA V 4850 tbl 02 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. Capacitance(1) Symbol CIN COUT Maximum Operating Temperature and Supply Voltage Grade Commercial Industrial Ambient Temperature(1) GND Vcc 0OC to +70OC 0V 3.3V + 0.3V -40OC to +85OC 0V 3.3V + 0.3V Parameter Input Capacitance Output Capacitance (TA = +25°C, f = 1.0MHz) Conditions(2) Max. Unit V IN = 3dV 9 pF VOUT = 3dV 10 pF 4850 tbl 05 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. 4850 tbl 03 NOTE: 1. This is the parameter TA. This is the "instant on" case temperature. 3 IDT70V38L High-Speed 3.3V 64K x 18 Dual-Port Static RAM Industrial and Commercial Temperature Ranges Truth Table I – Chip Enable(1,2) CE L Mode CE0 CE 1 VIL VIH < 0.2V >VCC -0.2V Port Selected (CMOS Active) VIH X Port Deselected (TTL Inactive) X VIL Port Deselected (TTL Inactive) >VCC -0.2V X(3) Port Deselected (CMOS Inactive) <0.2V Port Deselected (CMOS Inactive) H (3) X Port Selected (TTL Active) 4850 tbl 06 NOTES: 1. Chip Enable references are shown above with the actual CE0 and CE1 levels; CE is a reference only. 2. 'H' = VIH and 'L' = VIL. 3. CMOS standby requires 'X' to be either < 0.2V or >VCC-0.2V. Truth Table II – Non-Contention Read/Write Control Inputs(1) Outputs CE(2) R/W OE UB LB SEM I/O9-17 I/O0-8 Mode H X X X X H High-Z High-Z Deselected: Power-Down X X X H H H High-Z High-Z Both Bytes Deselected L L X L H H DATAIN High-Z Write to Upper Byte Only L L X H L H High-Z DATA IN Write to Lower Byte Only L L X L L H DATAIN DATA IN Write to Both Bytes L H L L H H DATA OUT High-Z Read Upper Byte Only L H L H L H High-Z DATA OUT Read Lower Byte Only L H L L L H DATA OUT DATA OUT Read Both Bytes X X H X X X High-Z High-Z Outputs Disabled 4850 tbl 07 NOTES: 1. A0L — A15L ≠ A0R — A15R 2. Refer to Truth Table I - Chip Enable. Truth Table III – Semaphore Read/Write Control(1) Inputs(1) Outputs CE(2) R/W OE UB LB SEM I/O9-17 I/O0-8 H H L X X L DATA OUT DATA OUT Read Data in Semaphore Flag X H L H H L DATA OUT DATA OUT Read Data in Semaphore Flag H ↑ X X X L DATAIN DATA IN Write I/O0 into Semaphore Flag X ↑ X H H L DATAIN DATA IN Write I/O0 into Semaphore Flag L X X L X L ______ ______ Not Allowed L X X X L L ______ ______ Not Allowed Mode NOTES: 1. There are eight semaphore flags written to I/O0 and read from all the I/Os (I/O0-I/O17). These eight semaphore flags are addressed by A0-A2. 2. Refer to Truth Table I - Chip Enable. 4 4850 tbl 08 IDT70V38L High-Speed 3.3V 64K x 18 Dual-Port Static RAM Industrial and Commercial Temperature Ranges DC Electrical Characteristics Over the Operating Temperature and Supply Voltage Range (VCC = 3.3V ± 0.3V) 70V38L Symbol Parameter Test Conditions (1) Min. Max. Unit |ILI| Input Leakage Current VCC = 3.6V, VIN = 0V to V CC ___ 5 µA |ILO| Output Leakage Current CE(2) = VIH, VOUT = 0V to V CC ___ 5 µA VOL Output Low Voltage IOL = +4mA ___ 0.4 V VOH Output High Voltage IOH = -4mA 2.4 ___ V 4850 tbl 09 NOTES: 1. At Vcc < 2.0V, input leakages are undefined. 2. Refer to Truth Table I - Chip Enable. DC Electrical Characteristics Over the Operating Temperature and Supply Voltage Range(5) (VCC = 3.3V ± 0.3V) 70V38L15 Com'l Only Symbol ICC ISB1 ISB2 ISB3 ISB4 Parameter Test Condition Version 70V38L20 Com'l & Ind Typ.(1) Max. Typ.(1) Max. Unit mA Dynamic Operating Current (Both Ports Active) CE = VIL, Outputs Disabled SEM = VIH f = fMAX(2) COM'L L 145 235 135 205 IND L ___ ___ 135 220 Standby Current (Both Ports - TTL Level Inputs) CEL = CER = VIH SEMR = SEML = VIH f = fMAX(2) COM'L L 40 70 35 55 IND L ___ ___ 35 65 (4) Standby Current (One Port - TTL Level Inputs) CE"A" = VIL and CE"B" = VIH Active Port Outputs Disabled, f=fMAX(2), SEMR = SEML = VIH COM'L L 100 155 90 140 IND L ___ ___ 90 150 Full Standby Current (Both Ports - All CMOS Level Inputs) Both Ports CEL and CER > VCC - 0.2V, VIN > VCC - 0.2V or V IN < 0.2V, f = 0(3) SEMR = SEML > VCC - 0.2V COM'L L 0.2 3.0 0.2 3.0 IND L ___ ___ 0.2 3.0 Full Standby Current (One Port - All CMOS Level Inputs) CE"A" < 0.2V and CE"B" > VCC - 0.2V(4), SEMR = SEML > VCC - 0.2V, VIN > VCC - 0.2V or V IN < 0.2V, Active Port Outputs Disabled , f = fMAX(2) COM'L L 95 150 90 135 IND L ___ ___ 90 145 mA mA mA mA 4850 tbl 10 NOTES: 1. VCC = 3.3V, TA = +25°C, and are not production tested. ICCDC = 90mA (Typ.) 2. At f = f MAX, 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. 3. f = 0 means no address or control lines change. 4. Port "A" may be either left or right port. Port "B" is the opposite from port "A". 5. Refer to Truth Table I - Chip Enable. 5 IDT70V38L High-Speed 3.3V 64K x 18 Dual-Port Static RAM Industrial and Commercial Temperature Ranges AC Test Conditions 3.3V Input Pulse Levels 3.3V GND to 3.0V Input Rise/Fall Times 590Ω 3ns Max. Input Timing Reference Levels 1.5V Output Reference Levels 1.5V Output Load DATAOUT BUSY INT DATAOUT 30pF 435Ω Figures 1 and 2 590Ω 435Ω 5pF* 4850 tbl 11 4850 drw 03 4850 drw 04 Figure 2. Output Test Load (for tLZ , tHZ, t WZ, tOW) * Including scope and jig. Figure 1. AC Output Load Waveform of Read Cycles(5) tRC ADDR (4) tAA (4) tACE (6) CE tAOE (4) OE tABE (4) UB, LB R/W tLZ tOH (1) DATAOUT VALID DATA (4) tHZ (2) BUSYOUT tBDD (3,4) 4850 drw 05 Timing of Power-Up Power-Down CE(6) tPU tPD ICC 50% ISB 50% 4850 drw 06 . NOTES: 1. Timing depends on which signal is asserted last, OE, CE, 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, t AA or tBDD . 5. SEM = VIH. 6. Refer to Truth Table I - Chip Enable. 6 IDT70V38L High-Speed 3.3V 64K x 18 Dual-Port Static RAM Industrial and Commercial Temperature Ranges AC Electrical Characteristics Over the Operating Temperature and Supply Voltage Range 70V38L15 Com'l Only Symbol Parameter 70V38L20 Com'l & Ind Min. Max. Min. Max. Unit READ CYCLE tRC Read Cycle Time 15 ____ 20 ____ ns tAA Address Access Time ____ 15 ____ 20 ns Chip Enable Access Time (3) ____ 15 ____ 20 ns tABE Byte Enable Access Time (3) ____ 15 ____ 20 ns tAOE Output Enable Access Time ____ 10 ____ 12 ns tOH Output Hold from Address Change 3 ____ 3 ____ ns 3 ____ 3 ____ ns ____ 10 ____ 10 ns 0 ____ 0 ____ ns ____ 15 ____ 20 ns 10 ____ ns ____ 20 tACE Output Low-Z Time tLZ (1,2) Output High-Z Time tHZ (1,2) Chip Enab le to Power Up Time tPU (2) (2) tPD Chip Disable to Power Down Time tSOP Semaphore Flag Update Pulse (OE or SEM) 10 ____ tSAA Semaphore Address Access Time ____ 15 ns 4850 tbl 12 AC Electrical Characteristics Over the Operating Temperature and Supply Voltage 70V38L15 Com'l Only Symbol Parameter 70V38L20 Com'l & Ind Min. Max. Min. Max. Unit 15 ____ 20 ____ ns tEW Chip Enable to End-of-Write (3) 12 ____ 15 ____ ns tAW Address Valid to End-of-Write 12 ____ 15 ____ ns 0 ____ 0 ____ ns ns WRITE CYCLE tWC Write Cycle Time (3) tAS Address Set-up Time tWP Write Pulse Width 12 ____ 15 ____ tWR Write Recovery Time 0 ____ 0 ____ ns tDW Data Valid to End-of-Write 10 ____ 15 ____ ns ____ 10 ____ 10 ns 0 ____ ns 10 ns ns tHZ tDH tWZ Output High-Z Time Data Hold Time (1,2) (4) 0 ____ (1,2) ____ 10 ____ (1,2,4) 0 ____ 0 ____ 5 ____ ns 5 ____ ns Write Enable to Output in High-Z tOW Output Active from End-of-Write tSWRD SEM Flag Write to Read Time 5 ____ tSPS SEM Flag Contention Window 5 ____ 4850 tbl 13 NOTES: 1. Transition is measured 0mV from Low or High-impedance voltage with Output Test Load (Figure 2). 2. This parameter is guaranted 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. 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. 7 IDT70V38L High-Speed 3.3V 64K x 18 Dual-Port Static RAM Industrial and Commercial Temperature Ranges Timing Waveform of Write Cycle No. 1, R/W Controlled Timing(1,5,8) tWC ADDRESS tHZ (7) OE tAW (9,10) CE or SEM (9) UB or LB tAS (6) tWP tWR (3) (2) R/W tWZ (7) tOW (4) DATAOUT (4) tDW tDH DATAIN 4850 drw 07 Timing Waveform of Write Cycle No. 2, CE Controlled Timing(1,5) tWC ADDRESS tAW CE or SEM (9,10) (6) tAS tWR (3) tEW (2) UB or LB(9) R/W tDW tDH DATAIN 4850 drw 08 NOTES: 1. R/W or CE or UB and LB = VIH during all address transitions. 2. A write occurs during the overlap (tEW or t WP) of a CE = VIL and a R/W = VIL 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 = VIL transition occurs simultaneously with or after the R/W = VIL 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 = VIL 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 = VIH 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 Truth Table I - Chip Enable. 8 IDT70V38L High-Speed 3.3V 64K x 18 Dual-Port Static RAM Industrial and Commercial Temperature Ranges Timing Waveform of Semaphore Read after Write Timing, Either Side(1) tSAA A0-A2 VALID ADDRESS VALID ADDRESS tAW tWR tACE tEW SEM tOH tSOP tDW I/O DATA OUT(2) VALID DATAIN VALID tAS tWP tDH R/W tSWRD OE tAOE tSOP Write Cycle Read Cycle 4850 drw 09 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/O 0 - I/O17 ) equal to the semaphore value. Timing Waveform of Semaphore Write Contention(1,3,4) A0"A"-A2"A" (2) SIDE "A" MATCH R/W"A" SEM"A" tSPS A0"B"-A2"B" (2) SIDE "B" MATCH R/W"B" SEM"B" 4850 drw 10 NOTES: 1. DOR = D OL = VIL, CEL = CER = VIH or both UB and 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. "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, the semaphore will fall positively to one side or the other, but there is no guarantee which side will be granted the semaphore flag. 9 IDT70V38L High-Speed 3.3V 64K x 18 Dual-Port Static RAM Industrial and Commercial Temperature Ranges AC Electrical Characteristics Over the Operating Temperature and Supply Voltage Range 70V38L15 Com'l Only Symbol Parameter 70V38L20 Com'l & Ind Min. Max. Min. Max. Unit BUSY TIMING (M/S=VIH) tBAA BUSY Access Time from Address Match ____ 15 ____ 20 ns tBDA BUSY Disable Time from Address Not Matched ____ 15 ____ 20 ns tBAC BUSY Access Time from Chip Enable Low ____ 15 ____ 20 ns tBDC BUSY Access Time from Chip Enable High ____ 15 ____ 17 ns tAPS Arbitration Priority Set-up Time (2) 5 ____ 5 ____ ns ____ 15 ____ 17 ns 12 ____ 15 ____ ns tBDD tWH (3) BUSY Disable to Valid Data (5) Write Hold After BUSY BUSY TIMING (M/S=VIL) tWB BUSY Input to Write(4) 0 ____ 0 ____ ns tWH Write Hold After BUSY(5) 12 ____ 15 ____ ns PORT-TO-PORT DELAY TIMING tWDD Write Pulse to Data Delay(1) ____ 30 ____ 45 ns tDDD Write Data Valid to Read Data Delay (1) ____ 25 ____ 30 ns 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". 10 4850 tbl 14 IDT70V38L High-Speed 3.3V 64K x 18 Dual-Port Static RAM Industrial and Commercial Temperature Ranges Timing Waveform of Write with Port-to-Port Read and BUSY (M/S = VIH)(2,4,5) tWC MATCH ADDR"A" tWP R/W"A" tDW tDH VALID DATAIN "A" tAPS (1) MATCH ADDR"B" tBAA tBDA tBDD BUSY"B" tWDD DATAOUT "B" VALID tDDD (3) 4850drw 11 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), 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". Timing Waveform of Write with BUSY (M/S = VIL) tWP R/W"A" tWB(3) BUSY"B" R/W"B" tWH (1) (2) 4850 drw 12 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. 11 . IDT70V38L High-Speed 3.3V 64K x 18 Dual-Port Static RAM Industrial and Commercial Temperature Ranges Waveform of BUSY Arbitration Controlled by CE Timing (M/S = VIH)(1,3) ADDR"A" and "B" ADDRESSES MATCH CE"A" tAPS (2) CE"B" tBAC tBDC BUSY"B" 4850 drw 13 Waveform of BUSY Arbitration Cycle Controlled by Address Match Timing (M/S = VIH)(1) ADDR"A" ADDRESS "N" tAPS (2) ADDR"B" MATCHING ADDRESS "N" tBAA tBDA BUSY"B" 4850 drw 14 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 Truth Table I - Chip Enable. AC Electrical Characteristics Over the Operating Temperature and Supply Voltage Range 70V38L15 Com'l Only Symbol Parameter 70V38L20 Com'l & Ind Min. Max. Min. Max. Unit INTERRUPT TIMING tAS Address Set-up Time 0 ____ 0 ____ ns tWR Write Recovery Time 0 ____ 0 ____ ns tINS Interrupt Set Time ____ 15 ____ 20 ns tINR Interrupt Reset Time ____ 15 ____ 20 ns 4850 tbl 15 12 IDT70V38L High-Speed 3.3V 64K x 18 Dual-Port Static RAM Industrial and Commercial Temperature Ranges Waveform of Interrupt Timing(1,5) tWC INTERRUPT SET ADDRESS ADDR"A" tAS (2) (3) tWR (4) CE"A" R/W"A" (3) tINS INT"B" 4850 drw 15 tRC ADDR"B" INTERRUPT CLEAR ADDRESS tAS (2) (3) CE"B" OE"B" tINR (3) INT"B" 4850 drw 16 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. Refer to 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 Truth Table I - Chip Enable. Truth Table IV — Interrupt Flag(1,4,5) Left Port Right Port R/WL CEL OEL A15L-A0L INTL R/WR CER OER A15R-A0R INTR L L X FFFF X X X X X L(2) X X X X X L X X L X X FFFE X L (3) Function Set Right INTR Flag X L L FFFF H (3) L L X FFFE X Set Left INTL Flag (2) X X X X X Reset Left INTL Flag H Reset Right INTR Flag 4850 tbl 16 NOTES: 1. Assumes BUSYL = BUSYR =VIH. 2. If BUSYL = VIL, then no change. 3. If BUSYR = VIL, then no change. 4. INTL and INTR must be initialized at power-up. 5. Refer to Truth Table I - Chip Enable. 13 IDT70V38L High-Speed 3.3V 64K x 18 Dual-Port Static RAM Industrial and Commercial Temperature Ranges Truth Table V — Address BUSY Arbitration(4) Inputs Outputs CEL CER AOL-A15L AOR-A15R BUSYL(1) BUSYR(1) Function X X NO MATCH H H Normal H X MATCH H H Normal X H MATCH H H Normal L L MATCH (2) (2) Write Inhibit(3) 4850 tbl 17 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 IDT70V38 are pushpull, 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 BUSY L 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 Truth Table I - Chip Enable. Truth Table VI — Example of Semaphore Procurement Sequence(1,2,3) Functions D0 - D17 Left D0 - D17 Right Status No Action 1 1 Semaphore free Left Port Writes "0" to Semaphore 0 1 Left port has semaphore token Right Port Writes "0" to Semaphore 0 1 No change. Right side has no write access to semaphore Left Port Writes "1" to Semaphore 1 0 Right port obtains semaphore token Left Port Writes "0" to Semaphore 1 0 No change. Left port has no write access to semaphore Right Port Writes "1" to Semaphore 0 1 Left port obtains semaphore token Left Port Writes "1" to Semaphore 1 1 Semaphore free Right Port Writes "0" to Semaphore 1 0 Right port has semaphore token Right Port Writes "1" to Semaphore 1 1 Semaphore free Left Port Writes "0" to Semaphore 0 1 Left port has semaphore token Left Port Writes "1" to Semaphore 1 1 Semaphore free NOTES: 1. This table denotes a sequence of events for only one of the eight semaphores on the IDT70V38. 2. There are eight semaphore flags written to via I/O0 and read from all I/O's (I/O0-I/O17 ). These eight semaphores are addressed by A0 - A2. 3. CE = VIH, SEM = VIL to access the semaphores. Refer to Truth Table III - Semaphore Read/Write Control. Functional Description 4850 tbl 18 flag (INTL) is asserted when the right port writes to memory location FFFE (HEX), where a write is defined as CER = R/WR = VIL per the Truth Table. The left port clears the interrupt through access of address location FFFE 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 FFFF (HEX) and to clear the interrupt flag (INTR), the right port must read the memory location FFFF. The message (18 bits) at FFFE or FFFF is user-defined since it is an addressable SRAM location. If the interrupt function is not used, address locations FFFE and FFFF are not used as mail boxes, but as part of the random access memory. Refer to Truth Table IV for the interrupt operation. The IDT70V38 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 IDT70V38 has an automatic power down feature controlled by CE. 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. 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 14 IDT70V38L High-Speed 3.3V 64K x 18 Dual-Port Static RAM Industrial and Commercial Temperature Ranges Busy Logic 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 the R/W signal. Failure to observe this timing can result in a glitched internal write inhibit signal and corrupted data in the slave. 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 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 70V38 RAM in master mode, are push-pull 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. Semaphores A16 CE0 MASTER Dual Port RAM BUSYL BUSYR CE0 SLAVE Dual Port RAM BUSYL BUSYR CE1 MASTER Dual Port RAM CE1 SLAVE Dual Port RAM BUSYL BUSYL BUSYR BUSYR 4850 drw 17 . Figure 3. Busy and chip enable routing for both width and depth expansion with IDT70V38 RAMs. Width Expansion with Busy Logic Master/Slave Arrays When expanding an IDT70V38 RAM array in width while using BUSY logic, one master part is used to decide which side of the RAMs 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 IDT70V38 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 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. The IDT70V38 is an extremely fast Dual-Port 64K x 18 CMOS Static RAM with 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, with both ports being 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 non-semaphore 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 III where CE and SEM are both HIGH. Systems which can best use the IDT70V38 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 IDT70V38s 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 IDT70V38 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 high-speed 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 a 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, 15 IDT70V38L High-Speed 3.3V 64K x 18 Dual-Port Static RAM Industrial and Commercial Temperature Ranges 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 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 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 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 a one to that latch. The eight semaphore flags reside within the IDT70V38 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, CE, 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 Truth 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 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 L PORT R PORT SEMAPHORE REQUEST FLIP FLOP D0 WRITE D Q SEMAPHORE REQUEST FLIP FLOP Q SEMAPHORE READ D D0 WRITE SEMAPHORE READ Figure 4. IDT70V38 Semaphore Logic 4850 drw 18 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. 16 IDT70V38L High-Speed 3.3V 64K x 18 Dual-Port Static RAM Industrial and Commercial Temperature Ranges Ordering Information IDT XXXXX Device Type A 999 A A Power Speed Package Process/ Temperature Range Blank I(1) Commercial (0°C to +70°C) Industrial (-40°C to +85°C) PF 100-pin TQFP (PN100-1) 15 20 Commercial Only Commercial & Industrial L Low Power 70V38 1152K (64K x 18) Dual-Port RAM Speed in nanoseconds 4850 drw 19 NOTE: 1. Contact your sales office for Industrial Temperature range in other speeds, packages and powers. Datasheet Document History: 08/01/99: 01/02/02: 08/29/03: Initial Public Offering Page 1 & 17 Replaced IDT logo Page 3 Increased storage temperature parameter Clarified TA Parameter Page 5 DC Electrical parameters–changed wording from "open" to "disabled" Page 4-6, 8 & 12 - 14 Added Truth Table I - Chip Enable to note 5 Page 7 Corrected ±200mV to 0mV in notes Page 5, 7, 10 & 12 Added Industrial Temperature range for 20ns to DC & AC Electrical Characteristics Removed Preliminary status 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 The IDT logo is a registered trademark of Integrated Device Technology, Inc. 17 for Tech Support: 831-754-4613 [email protected]