DS2118M Ultra2 LVD/SE Multimode SCSI Terminator

Product Features

The DS2118M Ultra2 LVD/SE Multimode SCSI Terminator provides termination for the emerging Low Voltage Differential (LVD) Ultra2 SCSI specifications. In addition, the multimode operation provides single-ended (SE) termination for legacy SCSI-1, Fast SCSI, and Ultra SCSI devices. The nine-line terminator contains circuitry to determine if the bus requires SE or LVD termination and automatically selects the proper operating mode. The DS2118M was designed for a low input capacitance of 3 pF that is necessary to support Ultra2 SCSI transfer rates of 40MHz. The DS2118M comes in a 36-pin SSOP package (DS2118MB).

Key Features

•Fully compliant with emerging Ultra2 SCSI specifications in LVD mode
•Fully compliant with SCSI-1, Fast SCSI and Ultra SCSI standards in the SE mode
•Provides multimode LVD/SE termination for 9 signal-line pairs
•5% tolerance on both SE and LVD termination resistance
•Mode-sensing circuitry automatically configures DS2118M for proper termination operation
•Low power-down capacitance of 3 pF
•>Onboard thermal shutdown circuitry
•SCSI bus hot plug-compatible
•Fully supports active negation in SE mode

Applications

High end PCs, workstations, SCSI host bus adapters, terminated cable assemblies, terminated connectors, RAID systems, SCSI peripherals.

What might seem to be a prosaic little part should make a lot of money for Dallas Semi if they market it right: it is a major volume part as the need for LVD termination has been growing apace while the grandfathered SCSI standards are not going away at any kind of velocity. The ability to individually choose either single-ended or differential termination on each of the nine signal-line pairs is an additional parts savings; this is particularly so on a lot of OEM designs I have seen being pushed out in volume in the Bay area. The auto-sensing is probably not that necessary for the majority of users who would probably as happily move a pin connection for each signal line, but it probably doesn't add any measurable cost either.

Termination tolerance is well within accepted standards, as is the input capacitance for the speed performance in Ultra 2, while the SCSI bus hot-plug capability and thermal shutdowns are essential, and not to be omitted, features for the applications.

The part is in a 36-pin SSOP with samples available now and production volumes in December.