The DS2118M is pin compatible and the DS2118M Ultra3 LVD/SE SCSI Terminator is both a low-voltage differential (LVD) and single-ended (SE) terminator. The multimode operation enables the designer to implement LVD in current products while allowing the end-user SE-backward compatibility with legacy devices. If the device is connected in an LVD-only bus, the DS2118M will use LVD termination. If any SE devices are connected to the bus, the DS2118M will use SE termination. This is accomplished automatically inside the part by sensing the voltage on the SCSI bus DIFFSENS line.
The DS2117M LVD/SE SCSI Terminator combines a low-voltage differential (LVD) and single-ended (SE) termination. The multimode operation enables the designer to combine LVD capability for current products with SE backwards-compatibility for legacy SCSI devices.
On an LVD-only bus, the DS2117M will use LVD termination. If any SE devices are connected to the bus, then it will use SE termination. If an HVD (high voltage differential) device is connected to the bus, then it will isolate the termination from the bus. All of this is accomplished automatically inside the part by sensing the voltage on the SCSI bus DIFFSENS line. An integrated digital filter eliminates the need for external passive components on the DIFFSENS line.
The DS2117M was designed for a low input capacitance of 3pF that is necessary to support Ultra SCSI transfer rates. Three DS2117M terminators can be used to terminate a wide SCSI bus. Applications include high-end PCs, workstations, SCSI host bus adapters, terminated cable assemblies, terminated connectors, RAID systems, and SCSI peripherals.
All Dallas terminators feature power-down mode with extremely low quiescent consumption. Different SCSI terminators are available to match every existing SCSI protocol and to address different design concerns, such as price, board space and voltage differential.
Key Features
Complies with SCSI-1, 2, and 3, Fast SCSI, Ultra, Ultra2, Ultra160, and Ultra320
Actively terminates 9 signal line pairs
Provides multimode low voltage differential/single-ended (LVD/SE) termination
Auto-selection of LVD or SE termination
5% tolerance on both LVD and SE termination resistance
* Some packages have variations, listed on the drawing. "PkgCode/Variation" tells which variation the product uses. Note that "+", "#", "-" in the part number suffix describes RoHS status. Package drawings may show a different suffix character.
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