DS21T05S/T&R

Overview

The DS21T05S/T&R is a SCSI terminator IC compliant with SCSI-1, Fast SCSI, and Ultra SCSI standards. It provides active termination for nine signal lines using laser-trimmed 110-ohm resistors with 5% tolerance. The device operates within a supply voltage range of 4.00V to 5.50V and supports an operating temperature range of 0°C to 70°C. It features a power-down mode that isolates termination resistors from the bus via the PD pin. The component is housed in a 16-pin plastic narrow SOIC package.

Feature Summary

• Fully compliant with SCSI-1, Fast SCSI, and Ultra SCSI standards
• Integrates nine precise-switched 110-ohm termination resistors
• Includes onboard thermal shutdown circuitry for protection
• Supports SCSI bus hot-plug operations

Applications

• Active termination at both ends of cable segments in SCSI systems
• Disk drive implementations requiring active termination
• RAID system components utilizing SCSI interfaces

Procurement Notes

Verify the specific suffix 'S' indicates the 300-mil wide SOIC package variant rather than the standard 150-mil version. Confirm RoHS compliance status through official manufacturer documentation as datasheet details may vary by production batch. Ensure the T&R designation matches required reel specifications for automated assembly processes.

Selection Notes

Select this component when high-volume applications require active termination without the higher performance specifications of the DS21T07. Verify compatibility with single-ended drivers and receivers. Ensure the design accommodates the requirement for external decoupling capacitors on TERMPWR and VREF pins to maintain stable operation under varying load conditions.

Part Context

The DS21T05 serves as a functionally compatible alternative to the DS21T07, targeting high-volume manufacturing environments. It integrates a regulator and nine termination resistors into a monolithic IC to simplify board design. The S variant specifically denotes the wider 300-mil SOIC package option available for this series.

Replacement Considerations

The DS21T07 is the primary functional equivalent offering higher performance specifications. Designers should verify if the relaxed output current and termination tolerances of the DS21T05 meet specific system requirements before substituting.