DS2108S

Overview

The DS2108S is a differential SCSI switchable terminator designed for High Voltage Differential (HVD) 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 complies with SCSI, SCSI-2, and SCSI-3 standards as well as the EIA RS-485 standard. Termination power voltage ranges from 4.00V to 5.25V. In active mode, typical current consumption is 56 mA, reducing to 1 mA in power-down mode. Laser-trimmed resistors maintain ±5% tolerance over the full temperature range.

Feature Summary

• Provides differential termination for nine pairs of signal lines using integrated 330-ohm and 150-ohm resistors.
• Supports switchable power-down mode controlled by software or hardware to isolate the device from the SCSI bus.
• Features low power-down capacitance of 6 pF per signal line, remaining below SCSI-3 allotments.

Applications

• High Voltage Differential (HVD) SCSI system termination
• Mid-bus termination control in SCSI architectures
• Compliance with SCSI-3 Parallel Interface (SPI) requirements

Procurement Notes

Verify component authenticity through authorized distributors or direct manufacturer channels due to discontinued status. Confirm RoHS compliance status as the product may not meet current environmental regulations. Validate pin configurations against specific board designs before integration. Check for available replacement components if long-term supply stability is required for production cycles.

Selection Notes

Select this component for HVD SCSI applications requiring precise termination resistance values. Ensure the design accommodates the 24-pin SOIC footprint and thermal requirements. Verify that the control logic can manage the Power Down pin state effectively. Consider the specific voltage levels supported by the SCSI bus environment to ensure compatibility with the -7 to +12 Volt operating range.

Part Context

The DS2108 series serves as a specialized interface solution for legacy SCSI infrastructure. Manufactured by Maxim Integrated, now part of Analog Devices Inc., it addresses the need for compact, surface-mount termination solutions. The device replaces conventional resistor SIPs, offering space savings while maintaining electrical performance standards defined by industry specifications for high-voltage differential signaling.

Replacement Considerations

Public confirmed substitute part numbers are not available in the provided documentation. Due to the discontinued status, alternative components must be evaluated based on functional equivalence, pin compatibility, and electrical specifications rather than direct cross-references.