DS21T07S/T&R

Overview

The DS21T07S is a SCSI terminator integrated circuit in a 16-pin SOIC package. It provides active termination for nine signal lines compliant with SCSI-1, Fast SCSI, and Ultra SCSI standards. The device integrates laser-trimmed 110 ohm termination resistors with 2% tolerance and a low dropout voltage regulator. Operating conditions include a TERMPWR voltage range of 4.00V to 5.50V and an operating temperature range of 0°C to 70°C. The quiescent current consumption is approximately 5 mA when all lines are in the quiescent state.

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
• Supports power-down mode to isolate termination resistors from the bus

Applications

• Active termination at both ends of cable segments in SCSI systems
• Integration into disk drives requiring SCSI bus termination
• Termination for RAID system components

Procurement Notes

Verify component authenticity through authorized distributors or direct manufacturer channels. Confirm RoHS compliance status and specific ordering suffixes against official documentation. Ensure supply chain integrity by checking for recent manufacturing date codes and valid traceability records prior to acquisition.

Selection Notes

Select the DS21T07S variant specifically for 16-pin surface mount applications requiring narrow body packaging. Verify that the design accommodates the required 4.7 µF capacitor between VREF pins and ground. Ensure the system architecture utilizes single-ended drivers and receivers compatible with the specified active termination requirements.

Part Context

This component belongs to the DS21T07 family of SCSI terminators manufactured by Analog Devices Inc./Maxim Integrated. It serves as a successor to earlier models like the DS2107 and DS21S07, offering backward compatibility while supporting higher speed SCSI standards. The S suffix denotes the 16-pin plastic SOIC package configuration.

Replacement Considerations

The DS21T07E is the electrically equivalent alternative utilizing a 20-pin TSSOP package. Designers must verify pinout compatibility and physical footprint differences before substituting the SOIC version with the TSSOP version in existing layouts.