Avago Technologies LSI53C120 - Manual (Page 16)

1-4 Introduction
Figure 1.1 on page 1-2 illustrates the connectivity of the LSI53C120 Ultra
SCSI Bus Expander device. A SCSI Single-ended (SE) bus connects
directly to the SCSI A-side. The interface signals are SCSI bus
compatible driver and receiver signals with no internal termination. The
SCSI B-side has the SE capable driver and receiver and also provides
the individual driver controls for external High Voltage Differential (HVD)
transceivers.
The LSI53C120 provides additional control capability through the pin
level SCSI bus disable mode. This feature allows logical disconnection of
both the A-side bus and B-side bus without disrupting transfers currently
in progress. For example, this feature allows electrical disconnection of
devices on the B-side to be swapped out while the A-side bus remains
active.
The TolerANT technology feature prevent glitches on the SCSI bus at
power-up or power-down, so other devices on the bus are also protected
from data corruption. For more detailed information about this
technology, refer to
Section 2.1.1.1, “TolerANT Drivers and Receivers,”
page 2-3 .
1.3 Application Examples
The following examples are typical applications for the LSI53C120 Ultra
SCSI Bus Expander. Many other configurations are possible and are only
limited by the imagination of the system architect.
1.3.1 Scalable Device Connectivity
Figure 1.2 illustrates how to use the LSI53C120 to increase the number
of devices to 15 on a 3 meter Ultra SCSI bus cable.