This document is about UCC5686, a twenty-seven line active terminator for low-voltage-differential (LVD) SCSI networks. This LVD SCSI-only design allows the user to reach peak bus performance, while reducing system cost. The device is designed as an active Y-terminator to improve the frequency response of the LVD SCSI Bus.
The UCC5686 and UCC5687 are active low‑voltage‑differential (LVD) terminators for Ultra2, Ultra3, Ultra160 and Ultra320 SCSI buses. They provide a 27‑line termination solution with a typical 2‑pF channel capacitance and optional disconnect control for selective line termination.
The devices are supplied in a 64‑pin low‑profile QFP package, operate from 2.7 V to 5.25 V, and include built‑in SPI‑3 delay circuitry. Detailed electrical characteristics, pin functions, and packaging options are provided for designers.
| Number of lines | 27 |
|---|---|
| Supply voltage (STRMPWR / PTRMPWR) | 2.7 V to 5.25 V |
| Typical channel capacitance | 2 pF |
| Differential bias voltage | 100 mV (typ) to 125 mV (max) |
| Output leakage current (DISCNCT) | 10 nA to 400 nA |
| Thermal shutdown threshold | 140 °C to 170 °C |
| Package type | 64‑pin low‑profile QFP |
Both devices operate from 2.7 V to 5.25 V.
The terminator supports 27 differential lines.
The typical channel capacitance is 2 pF.
For the UCC5687, pins DISCNCT1 and DISCNCT2 are left open to disable termination.