DS21T05Z/T&R

Overview

The DS21T05Z/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 on a TERMPWR voltage range of 4.0V to 5.5V, drawing typical quiescent current of 8mA and peak current up to 250mA. 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 narrow SOIC package (DS21T05Z) and supports hot-plug operations.

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 actively negated SCSI signals with low dropout voltage

Applications

• Active termination at both ends of SCSI cable segments
• Disk drive and RAID system components requiring SCSI bus termination
• High-volume applications needing functional compatibility with DS21T07

Procurement Notes

Verify the specific suffix 'Z' indicates the 150-mil narrow SOIC package variant as documented in the datasheet. Confirm the '/T&R' designation corresponds to reel or cut tape packaging formats. Ensure the source material explicitly links these suffixes to the physical dimensions and shipping method before procurement.

Selection Notes

Select this component when designing systems requiring compliance with SCSI-1, Fast SCSI, or Ultra SCSI standards. It serves as a functionally compatible alternative to the DS21T07 for high-volume applications where relaxed output current and termination tolerances are acceptable. Ensure the design accommodates the 16-pin narrow SOIC footprint.

Part Context

The DS21T05 is part of the Dallas Semiconductor/Maxim Integrated family of SCSI interface devices. It is designed as a cost-effective solution for active termination, offering lower performance specifications than the DS21T07 but maintaining functional compatibility. The Z suffix specifically denotes the 150-mil narrow SOIC package option within this product line.

Replacement Considerations

The DS21T07 is the higher-performance functional equivalent. Verify if the relaxed termination tolerances and output current limits of the DS21T05 meet the specific SCSI bus requirements of the target application.