UCC5617

The UCC5617 provides 18 lines of active termination for a SCSI (Small Computers Systems Interface) parallel bus. The SCSI standard recommends and Fast-20 (Ultra) requires active termination at both ends of the cable. Pin for pin compatible with the UC5609, the UCC5617 is ideal for high performance 5V SCSI systems, Termpwr 4.0V to 5.25V. During disconnect the supply current is only 50mA typical, which makes the IC attractive for lower powered systems.

The UCC5617 is designed with a low channel capacitance of 2pF, which eliminates effects on signal integrity from disconnected terminators at interim points on the bus.

The power amplifier output stage allows the UCC5617 to source full termination current and sink active negation current when all termination lines are actively negated.

The UCC5617, as with all Unitrode terminators, is completely hot pluggable and appears as high impedance at the terminating channels with TRMPWR=0V or open.

Internal circuit trimming is utilized, first to trim the 110W impedance, and then most importantly, to trim the output current as close to the maximum SCSI-3 specification as possible, which maximizes noise margin in fast SCSI operation. Other features include thermal shutdown and current limit.

This device is offered in low thermal resistance versions of the industry standard 28 pin wide body SOIC, TSSOP and PLCC.