DS21S07AS/T&R

Overview

The DS21S07AS/T&R is a SCSI terminator IC compliant with SCSI-1, Fast SCSI, and Ultra SCSI standards. It integrates a low-dropout regulator and nine laser-trimmed 110Ω termination resistors into a monolithic device. The component operates within a TERMPWR voltage range of 4.00V to 5.50V and supports an operating temperature range of 0°C to +70°C. It provides active termination for nine signal lines, featuring a reference output voltage of 2.85V typical. The device utilizes a 16-pin Plastic SO package and includes thermal shutdown circuitry.

Feature Summary

• Fully compliant with SCSI-1, Fast SCSI, and Ultra SCSI standards
• Integrates a low-dropout voltage regulator and nine precise 110Ω termination resistors
• Power-down mode electrically isolates termination resistors from the SCSI bus
• Includes on-board thermal shutdown circuitry for protection

Applications

• Active termination at both ends of cable segments in SCSI systems
• Termination for single-ended drivers and receivers in SCSI architectures
• Hot-plug compatible installations on disk drives or RAID system components

Procurement Notes

Verify the specific ordering suffix T&R indicates tape and reel packaging when sourcing this component. Confirm that the AS variant corresponds to the 16-pin Plastic SO package rather than the AE TSSOP option. Ensure compatibility with existing board layouts requiring the specific footprint dimensions associated with this package style before procurement.

Selection Notes

Select the DS21S07AS/T&R when designing for 8-bit or 16-bit wide SCSI buses requiring active termination. This part is suitable for applications needing intrinsic TERMPWR decoupling and enhanced noise immunity. Consider the 16-pin SO package constraints and verify that the required current sinking capabilities meet the actively negated SCSI signal requirements.

Part Context

The DS21S07A series serves as a backward-compatible replacement for the DS2107 and DS2107A terminators. It is manufactured by Analog Devices Inc./Maxim Integrated. The AS designation specifically identifies the 16-pin Plastic SO package version, distinct from the 20-pin TSSOP variant designated as AE.

Replacement Considerations

The DS21S07A is backward compatible with the DS2107 and DS2107A. Verify pinout compatibility and package dimensions when substituting these older models.