DS21T07E

Overview

The DS21T07E is a SCSI terminator integrated circuit manufactured by Analog Devices Inc./Maxim Integrated, housed in a 20-pin TSSOP 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 ohms termination resistors with 2% tolerance, a low dropout voltage regulator, and power-down functionality. 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 regulator output voltage typically measures 2.85V, with a maximum drop-out voltage of 0.75V.

Feature Summary

• Fully compliant with SCSI-1, Fast SCSI, and Ultra SCSI standards while maintaining backward compatibility with earlier DS2107 series devices.
• Integrates nine precise switched 110 ohms termination resistors and a bandgap reference circuit to ensure enhanced noise immunity and intrinsic TERMPWR decoupling.
• Features onboard thermal shutdown circuitry and a power-down mode that electrically isolates the termination resistors from the bus without physical removal.

Applications

• Active termination at both ends of cable segments in SCSI systems utilizing single-ended drivers and receivers.
• Integration into disk drives requiring hot-plug compatible SCSI bus connections.
• Termination implementation within RAID system components to maintain bus integrity during peripheral insertion or removal.

Procurement Notes

Verify component authenticity through authorized distributors or direct manufacturer channels due to discontinued status. Confirm package integrity and pin alignment against the 20-pin TSSOP specification before installation. Review datasheet revision history for any manufacturing changes. Ensure supply chain documentation matches the specific DS21T07E suffix requirements for the thin shrink small outline package variant.

Selection Notes

Select the DS21T07E when a 20-pin surface-mount solution is required for terminating up to nine SCSI signal lines. This model replaces the 16-pin SOIC variant (DS21T07S) where board space constraints favor the thinner TSSOP footprint. Ensure design accommodates the necessary external decoupling capacitors for VREF and TERMPWR pins as specified in the functional description section of the datasheet.

Part Context

The DS21T07E belongs to the DS21T07 family of SCSI terminators designed for high-speed data transmission environments. It serves as a successor to legacy passive termination methods, offering superior signal quality through active regulation. The E suffix specifically denotes the 20-pin Thin Shrink Small Outline Package, distinguishing it from the standard 16-pin SOIC configuration available in the same product line.

Replacement Considerations

The DS21T07S is the pin-compatible alternative using a 16-pin SOIC package. Verify mechanical clearance and solder mask definitions when substituting between TSSOP and SOIC footprints. No other direct electrical substitutes are documented in the provided source material.