We are currently prototyping and manufacturing Low Voltage Differential (LVD) SCSI cables,
Auto-sensing Low-Voltage / High-Voltage Terminators and Transceivers. Please E-mail or call our Technical Support group with any questions or specific LVD requirements.
Low Voltage Differential SCSI Fundamentals
Low Voltage Differential (LVD) SCSI is defined under the Ultra subset of the SCSI-3 standard. Industry wide, the terms LVD and Ultra SCSI are used interchangeably. LVD is ushering in greater I/O
bandwidth, improved device connectivity, data reliability, and greater cable lengths.
The LVD Advantages
LVD provides SCSI bus data rates of 80 Mbytes/sec. That's double the fastest SCSI-2 standard (40 Mbytes/sec), and immensely ahead of the SCSI-1 standard used prior to 1992 in which SCSI bus
rates were as slow as 3 Mbytes/sec.
Besides increasing the maximum burst transfer rates to 80 Mbytes/sec, LVD SCSI provides
differential data integrity, extends the SCSI bus cable lengths to 25 meters (12 meters with 16 devices) and provides easy system configuration for up to 16 devices. This is a dramatic increase from
Ultra SCSI single-ended cable restrictions of 3 meters and maximum burst transfer rates of 40 Mbytes/sec.
LVD is a subset of the SCSI-3 standard. LVD devices will work on SCSI-1 and SCSI-2 bus segments. Conversely, older SCSI-1 and SCSI-2 single-ended devices will work on an LVD bus.
What's important to remember is that the Low-Voltage Differential, LVD transceiver technology offers full compatibility with older SCSI devices in the existing installed base.
LVD Cables
LVD spec shielded external cable is required for low voltage differential applications. External
LVD cable meet the maximum rated impedance of 135 Ohms as well as conform to the Time Delay, Time Delay Skew, and Attenuation specs. External LVD cables can be built with 28AWG and 30AWG
cable, enabling the use of any 68-pin cable connector.
LVD spec internal ribbon cable
is required for low voltage differential applications. Internal LVD cables meet the maximum rated impedance of 135 Ohms as well as conform to the Time Delay, Time Delay Skew, and Attenuation specs.
Companies already heavily involved with LVD include: Adapted, AT, Diamond, Inuit, Logic, Symbols Logic, and Tekram. |
