The UCC5611 provides 18 lines of active termination for a SCSI (Small Computer Systems Interface) parallel bus. The SCSI standard recommends active termination at both ends of the cable segment. The UCC5611 is ideal for high performance 3.3-V SCSI systems. The key features contributing to such low-operating voltage are the 0.1-V drop-out regulator and the 2.75-V reference. During disconnect the supply current is typically only 1 A, which makes the IC attractive for battery powered systems. The UCC5611 is designed with an ultra-low channel capacitance of 1.8 pF, which eliminates effects on signal integrity from disconnected terminators at interim points on the bus. The UCC5611 can be programmed for either a 110- or 2.5-k termination. The 110- termination is used for standard SCSI bus lengths and the 2.5-k termination is typically used in short bus applications. When driving the TTL compatible DISCNCT pin directly, the 110- termination is connected when the DISCNCT pin is driven high, and disconnected when low. When the DISCNCT pin is driven through an impedance between 80 k and 150 k, the 2.5-k termination is connected when the DISCNCT pin is driven high, and disconnected when driven low.