X3T9.2/90-154 TO: X3T9.2 Committee Members, Liason and Observers FROM: Chuck Micalizzi Emulex (714) 662-5600 ext 3166 c_micalizzi@emulex.com DATE: Oct. 2 1990 SUBJECT: Low Power Differential SCSI Working Group On Sept. 26 1990 a special working group met at the Newport Beach, Ca. Sheraton to discuss creating a Low Power Differential Interface for SCSI-3. I would like to thank everyone who attended. The level of participation was excellent. Included in this mailing is a list of attendees (mailing addresses), preliminary specification, and a list of action items M E E T I N G N O T I C E There will be a second Low Power Differential SCSI working group meeting to be held from 2:30pm to 5:00pm Oct. 29 1990 in conjunction with the November SCSI Working Group in Austin Texas. The meeting will be held at the Stoufer Austin Hotel 9721 Arboretum Blvd. Austin Texas, reservation can be made by calling 512-343-2626. (see the November Working Group Meeting Notice from the October Mailing X3T9.2/90-135). See you in Austin, Chuck ----------(page)------------ Meeting Attendees and Mailing Addresses Marc Friedmann Carrie Claflin AMCC Hewlett-Packard 6195 Lusk Blvd. P.O. Box 39 San Diego, Ca. 92121 MS 216 (619) 535-6516 Boise, ID 83704 FAX (619) 450-9885 (208) 323-4182 FAX (208) 323-2251 Tim Thompson Roger Dimmick AMCC IBM 6195 Lusk Blvd. Hwy 52 & 37st San Diego, Ca. 92121 Rochester, Mn (619) 535-6516 (507) 253-2027 FAX (619) 450-9885 FAX (507) 253-5319 Doug Makishima David Steele Adaptec NCR 691 S. Milpitas Blvd. 1635 Aeroplaza Milpitas, Ca. 95035 Colorado Springs, Co. 80916 (408) 945-8600 ext. 2162 (719) 596-5795 FAX (408) ???-???? FAX (719) 570-8225 Boyd Pett Ted Mlynar Cirrus Logic, Inc. NCR 1463 Centre Pointe Dr. 1635 Aeroplaza Milpitas, Ca. 95035 Colorado Springs, Co. 80916 (408) 945-8300 (719) 596-5795 FAX (408) 263-5682 FAX (719) 570-8225 Jim Shaffner Luke A. Perkins Emulex Micro Devices NCR 3545 Harbor Blvd. 1635 Aeroplaza Costa Mesa, Ca. 92626 Colorado Springs, Co. 80916 (714) 668-5365 (719) 596-5795 FAX (714) 754-0731 FAX (719) 570-8225 Chuck Micalizzi Ed Shurig Emulex Micro Devices Texas Instruments 3545 Harbor Blvd. M/S 8206 Costa Mesa, Ca. 92626 8360 LBJ Freeway (714) 668-5600 ext. 3166 Dallas, Tx 75265 FAX (714) 754-0731 (214) 997-3384 FAX (214) ???-???? Ken Post Mike Bartlett Future Domain Texas Instruments 2801 Mcgaw Ave. M/S 8206 Irvine, Ca. 92714 8360 LBJ Freeway (714) 253-0495 Dallas, Tx 75265 FAX (714) 253-0913 (214) 997-3308 FAX (214) ???-???? ----------(page)------------ Meeting Attendees and Mailing Addresses Kevin Gingerich Ken Erickson Texas Instruments Micropolis M/S 8206 21211 Nordhoff 8360 LBJ Freeway Chatsworth, Ca. 91311 Dallas, Tx 75265 (818) 718-5113 (214) 997-3165 FAX (818) 709-3497 FAX (214) ???-???? Andrew Jue Eric Jessen National Semiconductor Western Digital 2900 Semiconductor Dr. 8105 Irvine Center Drive P.O. Box 58090 Irvine, Ca. 92718 Santa Clara, Ca. 95052-8090 (714)932-6612 M/S D-3969 (408) 721-7795 FAX (408) 739-6204 Don Chin National Semiconductor 2900 Semiconductor Dr. P.O. Box 58090 Santa Clara, Ca. 95052-8090 M/S E200 (408) 721-7916 FAX (408) 739-6204 Gary Murdock National Semiconductor 2900 Semiconductor Dr. P.O. Box 58090 Santa Clara, Ca. 95052-8090 M/S D-3969 (408) 721-7269 FAX (408) 739-6204 ----------(page)------------ Alternative-Differential Specification : PRELIMINARY -------------------------------------- Author: E. Jessen Date: 9-26-90 1. REQUIREMENTS a. At least 8 devices per system. b. 16-bit data bus. c. Each SCSI device must be capable of being implemented in a single device using a digital CMOS process. This implies a max. power dissipation of 1.0 to 1.5W per SCSI device. d. Data error rates lower than single-ended. e. At least 10MT/s (mega-transfers per second). f. Minimum cable length of 6m. g. lower power consumption than present differential. 2. GOALS a. Develop an overal specification suitable for a workstation or in-cabinet environment. c. Higher data rates. 20 mega-transfers very much desired. d. 25m cable length. e. 16 devices per system. f. clearly specify system considerations previously ignored: - "hot-plugging" effects and design requirements. - cable specification - common-mode ranges ----------(page)------------ 3. TRANSCIEVER REQUIREMENTS abs. abs. min max min max units notes --- --- --- --- ----- ----- Iil -50 +50 uA (1) Iih -50 +50 uA (1) Vinput 0.0 +5.0 -0.5 5.5 V (2) | Vid | 200 mV (3) input hysteresis 35 mV input impedance 12 k-ohm (4) input capacitance 25 pF | Vod | 0.5 V (5) Ioh (Voh = 2.7V) -55 mA (6) Iol (Vol = 2.2V) +55 mA (6) Ios1 ?? mA (7) Ios2 ?? mA (8) (1) Iil and Iih include leakage current of tristated outputs and of input receivers. (2) Voltage at connection to SCSI bus, when outputs are tristate, measured relative to local ground. (3) Vid = Va - Va-, where A and A- are the differential inputs to the device. Va and Va- must be separated by at least 200mV for a valid signal level to be recognized. (4) This needs further specification: - some max and min | Z | over some frequency range (5) Vod = Va - Va-, where A and A- are the differential outputs of the device. (6) As Voh nears VDD, or Vol nears GND, Ioh and Iol values may drop below this minimum. (7) Shorted to 5V. (8) Shorted to 0V. Values exceeding min and max levels may cause the device not to function properly. Values exceeding absolute min and max levels may cause permanent damage to the device. ----------(page)------------ 4. Termination There are two termination schemes under consideration: The first is the traditional three-resistor termination. The new, preferred method is a single series resistor between A and A-, with bias circuitry contained within each SCSI device. 4A. Original Method. R1 is the resistor connected between the two differential signals. R2 is the resistor connected from the power lines to the differential signals. Resistor values are subject to change. min nom max. units notes --- --- ---- ----- ----- Vterm 4.0 4.5 5.25 V R1 123 125 127 ohms (1) R2 544 550 556 ohms (1) eff. impedance 100 ohms current from Vterm 4 mA current to ground 5 mA (1) Five percent tolerance. Termination should be designed so that, when no devices are driving a signal, at least 500mV of bias voltage exists between A and A-. There are two sub-methods: one using symmetric differential, and the other using asymmetric differential. 4B. New Method. A series resistor, in the 120 ohm range, is connected at each end of the cable between each pair of differential lines. There is no TERMPOWER line in the design, and TERMPOWER lines in the cable will be marked as RESERVED, and left open, to prevent device damage should a new SCSI device be plugged into an old SCSI system. Each input receiver on each SCSI device will have internal bias circuitry. A schematic of this circuitry is under development. Termination resistor tolerance of 5% should be sufficient. 5. Notes A. It may be necessary to specify varying values of termination, as a function of number of devices on the cable. B. This system is not compatible with present differential. ----------(page)------------ AGENDA FOR NEXT MEETING ----------------------- a. Review TI's SPICE results for max. power dissipation. b. Determine appropriate termination scheme. c. Determine packaging feasibility. d. Review TI's SPICE results for max. transfer rate. e. Review IBM's hot-plugging considerations. f. Collect a list of internet addresses of attendees ACTION ITEMS ------------ a. Hot-plugging IBM-Rochester - definition of terms - effects of hot-plugging and active-plugging - design requirements to minimize adverse effects. b. Power-supply effects on common-mode noise - all attendees are generally urged to research the issue. c. Define specific packages for 8-bit and 16-bit versions. This will be used in analyzing feasibility of integrating into a single device. d. Define max. power dissipation e. SPICE power dissipation for new termination TI f. SPICE to see if new termination will run up to 20MT/s. TI g. Generate new SCSI signal pin assignment.