Seagate ST318438LW manual Low voltage differential I/O circuits, General cable characteristics

Page 81

Barracuda 36ES2 Product Manual, Rev. B

 

 

71

Table 16: Cable characteristics for single-ended circuits

 

 

 

 

 

 

 

 

 

 

Maximum number of

Maximum cable

Transmission line impedance

 

 

 

 

 

I/O transfer rate

devices on the bus

length allowed

REQ/ACK

Other signals

 

 

 

 

 

 

 

 

 

 

 

 

 

<10M transfers/s

16 (wide SCSI bus)

6 meters (19.7 ft)

90 + 6 Ohms

90 + 10 Ohms

 

 

 

 

 

 

 

<20M transfers/s

4 (wide SCSI bus)

3 meters (9.8 ft)

90 + 6 Ohms

90 + 10 Ohms

 

 

 

 

 

 

 

<20M transfers/s

8 (wide SCSI bus)

1.5 meters (4.9 ft)

90 + 6 Ohms

90 + 10 Ohms

 

 

 

 

 

 

 

A stub length of no more than 0.1 meter (0.33 ft) is allowed off the mainline interconnection with any connected equipment. The stub length is measured from the transceiver to the connection to the mainline SCSI bus.

Single-ended I/O cable pin assignments for LW drives are shown in Table 15.

9.7.1.3Low voltage differential I/O circuits

The maximum total cable length for use with drives using LVD I/O drivers and receiver circuits is 12 meters (39.37 ft.). A stub length of no more than 0.1 meter is allowed off the mainline interconnection with any con- nected equipment. LVD I/O pin assignments for LW model drives are shown in tables 14 and 15.

9.7.1.4General cable characteristics

A characteristic impedance of 100 ohm + 10% is recommended for unshielded flat or twisted pair ribbon cable. However, most available cables have a somewhat lower characteristic impedance. To Minimize discontinuities and signal reflections, cables of different impedances should not be used in the same bus. Implementations may require trade-offs in shielding effectiveness, cable length, the number of loads, transfer rates, and cost to achieve satisfactory system operation. If shielded and unshielded cables are mixed within the same SCSI bus, the effect of impedance mismatch must be carefully considered. Proper impedance matching is especially important in order to maintain adequate margin at fast SCSI transfer rates.

Image 81 Seagate ST318438LW, ST318418N, ST336938LW, ST336918N Low voltage differential I/O circuits, General cable characteristics
Contents Product Manual, Volume Page Product Manual, Volume Page Revision Date Writer/Engineer Sheets Affected Revision status summary sheetPage Contents Installation Defect and error managementSeagate Technology support services Interface requirementsBarracuda 36ES2 Product Manual, Rev. B Vii List of FiguresPage Barracuda 36ES2 family drive ST336938LW shown ScopeBarracuda 36ES2 Product Manual, Rev. B Applicable standards and reference documentation Australian C-Tick Korean MICTaiwanese Bsmi General description Media characteristics Standard featuresPerformance ReliabilityFactory installed accessories Options factory installedProgrammable drive capacity Performance characteristics Ultra2 Scsi Ultra160 Scsi Start/stop timePrefetch/multi-segmented cache control Caching write data Cache operationPrefetch operation Barracuda 36ES2 Product Manual, Rev. B Reliability specifications Preventive maintenance Reliability and serviceService life Service philosophyControlling S.M.A.R.T 7 S.M.A.R.TReporting control Performance impactDetermining rate Predictive failuresDST Failure Definition State of the drive prior to testingImplementation Invoking DSTShort test Function Code 001b Product warrantyExtended test Function Code 010b Log page entriesProduct repair and return information Barracuda 36ES2 Product Manual, Rev. B Physical/electrical specifications AC power requirementsDC power requirements Power sequencing Conducted noise immunity3 12 V Current profile +5 Volt Current during spindle start Typical Amper es Amps Power dissipation ST336938/ST318438 Barracuda 36ES2 Product Manual, Rev. B ST336918/ST318418 Environmental limits TemperatureEffective altitude sea level Barracuda 36ES2 Product Manual, Rev. B Relative humidityShock and vibration ShockRecommended mounting Air cleanliness Barracuda 36ES2 Product Manual, Rev. B VibrationAcoustics Dimension Table Mechanical specificationsMounting configuration dimensions Barracuda 36ES2 Product Manual, Rev. B Defect and error management Drive error recovery proceduresDrive internal defects Scsi systems errors Configure drive options InstallationFormatting Drive ID/option select headerDo not install jumpers retain cover J6 jumper header for N model J5 jumper header on LW models only J2 option select header for LW models Barracuda 36ES2 Product Manual, Rev. B Barracuda 36ES2 Product Manual, Rev. B Function description Drive orientation CoolingAir flow Grounding Barracuda 36ES2 Product Manual, Rev. B Drive mountingBarracuda 36ES2 Product Manual, Rev. B Scsi interface messages supported Interface requirementsScsi interface commands supported Commands supported by Barracuda 36ES2 family drives Barracuda 36ES2 Product Manual, Rev. B Vendor ID Unit serial number page 80h Inquiry Vital Product dataImplemented operating definition page 81h Firmware numbers page C0hJumper settings page C2h Mode Sense data DEF CHG Barracuda 36ES2 Product Manual, Rev. B Condition/features supported Supported Status supported DC cable and connector 2 REQ/ACK offsetPhysical interface Model drive physical interface 50-pin Scsi I/O connector Pin Power Scsi interface cable requirements Scsi interface physical descriptionMating connectors for N model drives Barracuda 36ES2 Product Manual, Rev. B Mating connectorsScsi daisy chain interface cabling for N drives Nonshielded 68 pin Scsi device connector used on LW drives Scsi daisy chain interface cabling for LW drives GND GND DBP1 +DBP1 Multimode signals Electrical descriptionMultimode-SE and LVD alternatives LVD output signals Input characteristicsReceiver characteristics Transmitter characteristicsSingle-ended drivers/receivers for N models Single-ended drivers/receivers for LW modelsLow voltage differential I/O circuits General cable characteristicsTerminator power Drives Terminator requirementsLW drives Page Following table provides drive activity LED status Drive activity LEDAutomated Services Seagate Technology support services Online ServicesPresales Support Technical SupportCustomer Service CSO USA/Canada/Latin America Support ServicesEuropean Support Services Africa/Middle East Support Services Asia/Pacific Support ServicesCall Center Toll-free Direct dial Barracuda 36ES2 Product Manual, Rev. B Index Diffsens LED PCB System chassis Barracuda 36ES2 Product Manual, Rev. B