Avago Technologies LSI53C1000R - Manual (Page 24)

1-6 Introduction
Version 2.2 Copyright © 2000–2003 by LSI Logic Corporation. All rights reserved.
allows a longer SCSI cable and more devices on the bus, with the same
cables defined in the SCSI-3 Parallel Interface standard for 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 LSI53C1000R
features universal LVDlink transceivers that support LVD SCSI and SE
SCSI. This allows use of the LSI53C1000R in both legacy and Ultra160
SCSI applications.
1.5 Benefits of TolerANT
®
Technology
The LSI53C1000R 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.
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, which is the single biggest reliability
issue with SCSI operations. TolerANT input signal filtering is a built-in
feature of the LSI53C1000R and all LSI Logic Fast, Ultra, Ultra2, and
Ultra160 SCSI devices.
The benefits of TolerANT technology include increased noise immunity
when the signal transitions to HIGH, better performance due to balanced
duty cycles, and improved fast SCSI transfer rates. In addition,
TolerANT SCSI devices do not cause glitches on the SCSI bus at
power-up or power-down. This protects other devices on the bus from
data corruption. When used with the LVDlink transceivers, TolerANT
technology provides excellent signal quality and data reliability in real
world cabling environments. TolerANT technology is compatible with both
the Alternative One and Alternative Two termination schemes proposed
by the American National Standards Institute.