Avago Technologies LSI53C896 - Manual (Page 23)

Benefits of LVDlink Technology 1-5
Version 3.3 Copyright © 1998–2003 by LSI Logic Corporation. All rights reserved.
1.3 Benefits of LVDlink Technology
The LSI53C896 supports LVD for SCSI, a signaling technology that
increases the reliability of SCSI data transfers over longer distances than
are supported by SE SCSI. The low current output of LVD allows the I/O
transceivers to be integrated directly onto the chip. LVD provides the
reliability of HVD SCSI without the added cost of external differential
transceivers. Ultra2 SCSI with LVD allows a longer SCSI cable and more
devices on the bus, with the same cables defined in the SCSI-3 Parallel
Interface standard for Fast-20 (Ultra SCSI). LVD provides a long-term
migration path to even faster SCSI transfer rates without compromising
signal integrity, cable length, or connectivity.
For backward compatibility to existing SE devices, the LSI53C896
features universal LVDlink transceivers that can support LVD SCSI, SE,
and HVD modes. The LVDlink technology also supports HVD signaling
in legacy systems, when external transceivers are connected to the
LSI53C896. This allows the LSI53C896 to be used in both legacy and
Ultra2 SCSI applications.
1.4 TolerANT
®
Technology
The LSI53C896 features TolerANT technology, which includes active
negation on the SCSI drivers and input signal filtering on the SCSI
receivers. Active negation causes the SCSI Request, Acknowledge,
Data, and Parity signals to be actively driven HIGH rather than passively
pulled up by terminators. Active negation is enabled by setting bit 7 in
the
SCSI Test Three (STEST3) register.
TolerANT receiver technology improves data integrity in unreliable cabling
environments, where other devices would be subject to data corruption.
TolerANT receivers filter the SCSI bus signals to eliminate unwanted
transitions, without the long signal delay associated with RC-type input
filters. This improved driver and receiver technology helps eliminate double
clocking of data, the single biggest reliability issue with SCSI operations.
TolerANT input signal filtering is a built-in feature of the LSI53C896 and all
LSI Logic fast SCSI, Ultra SCSI, and Ultra2 SCSI devices.