DS2108S/T&R

Overview

The DS2108S/T&R is a differential SCSI switchable terminator designed for High Voltage Differential (HVD) SCSI systems. It integrates eighteen 330-ohm and nine 150-ohm precise switched termination resistors into a monolithic IC housed in a 24-pin plastic SOIC package. The device operates with SCSI signal voltages ranging from -7 to +12 Volts and conforms to EIA RS-485 standards. Termination resistance values are laser-trimmed with ±5% tolerance over the full temperature range. In active mode, the typical current consumption is 56 mA at 5V, while power-down mode reduces this to approximately 1 mA. The component supports switching between powered-on and powered-off states via software or hardware control.

Feature Summary

• Integrates eighteen 330-ohm and nine 150-ohm precise switched termination resistors within a single monolithic IC
• Provides differential termination for nine pairs of signal lines compliant with SCSI, SCSI-2, and SCSI-3 standards
• Features switchable power-down mode that isolates terminator blocks from the bus with low capacitance
• Operates across a wide voltage range supporting SCSI signal levels from -7 to +12 Volts

Applications

• High Voltage Differential (HVD) SCSI system terminators
• Mid-bus termination for 8-bit SCSI devices
• Termination solutions for 16-bit SCSI devices

Procurement Notes

Verify the specific suffix T&R indicates tape and reel packaging when sourcing components. Confirm RoHS compliance status as the base part may have non-compliant variants. Check for obsolescence notices since the product line has been discontinued by Analog Devices/Maxim Integrated. Ensure the supplier provides valid datasheets matching the DS2108 specification for design validation.

Selection Notes

Select this component for HVD SCSI applications requiring switchable termination capabilities. It is suitable for designs needing to reduce bus capacitance during inactive states. Verify compatibility with SCSI-3 Parallel Interface (SPI) requirements for TERMPWR bypassing. Consider board space savings compared to conventional resistor SIPs due to the surface mount SOIC package format.

Part Context

The DS2108 belongs to the family of SCSI interface integrated circuits manufactured by Maxim Integrated, now part of Analog Devices. It serves as a specialized terminator for high-voltage differential signaling environments. The device replaces discrete resistor networks, simplifying PCB layout for SCSI controllers and peripherals requiring precise impedance matching.

Replacement Considerations

Public confirmed substitute part numbers are not available in the provided documentation. The DS2108 series is listed as obsolete. Designers should consult manufacturer recommendations for end-of-life alternatives or evaluate modern SCSI interface solutions compatible with current standards.