UCC5617 is a SCSI (Small Computers Systems Interface) parallel bus 18-line active terminator produced by Unitrode. This terminator is pin-compatible with UC5609, and is ideal for high-performance 5V SCSI systems with an input voltage of 4.0-5.25V. The supply current is only 50mA during disconnection, making the IC attractive for lower powered systems. The UCC5617 is designed with a low channel capacitance of 2pF, which eliminates the effects of disconnected terminators at intermediate points on the bus on signal integrity. When all termination lines are actively negated, the power amplifier output stage of the UCC5617 can source full termination current and sink active negation current. Like all Unitrode terminators, the UCC5617 is completely hot pluggable and appears as high impedance at the terminating channels with TRMPWR = 0V or open. Internal circuit trimming is used to first trim the 110 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. This device is offered in low thermal resistance versions of the industry standard 28-pin wide body SOIC.
The UCC5617 provides 18 lines of active termination for SCSI parallel buses, complying with SCSI‑2, SCSI‑3, SPI and FAST‑20 standards. It features a low 2 pF channel capacitance during disconnect, 50 pA typical supply current in disconnect mode, and hot‑plug compliance, making it suitable for high‑performance 5 V SCSI systems.
Key specifications include a trimmed 110 Ω termination impedance, +400 mA sinking current for active negation, –650 mA sourcing current for termination, thermal shutdown at 170 °C, and an internal 2.8 V regulator. The device is offered in SOIC‑28 packages with various RoHS‑compliant options.
| Channel Capacitance (Disconnect) | 2 pF |
|---|---|
| Supply Current (Disconnect Mode) | 50 pA typical |
| Termination Impedance | 110 Ω |
| Thermal Shutdown Temperature | 170 °C |
The device has a channel capacitance of 2 pF during disconnect.
It draws 50 pA typical supply current in disconnect mode.
The termination impedance is trimmed to 110 Ω.
Thermal shutdown occurs at 170 °C.