DS2120B

Overview

The DS2120B is an Ultra3 LVD SCSI terminator manufactured by Analog Devices Inc./Maxim Integrated. It provides low-voltage differential termination for nine signal line pairs in a 36-pin SSOP package. The device operates within a voltage range of 2.7V to 5.5V and supports a temperature range of 0°C to +70°C. Key electrical parameters include a typical differential mode termination resistance of 110 Ω, common mode termination resistance of 190 Ω, and output capacitance of 3pF. The part integrates precision laser-trimmed resistors and current sources to ensure accurate impedance matching.

Feature Summary

• Fully compliant with Ultra3, Ultra160, Ultra320, and Ultra2 (LVD only) SCSI standards
• Integrates zero temperature coefficient termination resistors with 5% tolerance on LVD termination resistance
• Features built-in mode change filter/delay and on-board thermal shutdown circuitry
• Supports SCSI bus hot plug compatibility with low power-down capacitance

Applications

• RAID Systems
• SCSI Host Bus Adapter Cards (HBA)
• Servers
• Network Attached Storage (NAS)
• Storage Area Networks (SANs)

Procurement Notes

Verify the specific ordering suffix when sourcing this component, as variations such as tape and reel packaging exist. Confirm that the lead time and availability status align with project requirements, noting that older interface components may have limited supply chains or end-of-life statuses from the manufacturer.

Selection Notes

Select the DS2120B for designs requiring Ultra3 LVD SCSI termination in standard industrial temperature ranges. Ensure the system utilizes a 36-pin SSOP footprint. Verify that the application does not require single-ended or high-voltage differential support, as the device isolates automatically in those modes. Check if the tape and reel variant is needed for automated assembly processes.

Part Context

The DS2120B belongs to the DS2120 family of Ultra3 LVD SCSI terminators. It serves as a critical interface component for maintaining signal integrity in parallel SCSI architectures. The device distinguishes itself through automatic mode detection, ensuring safe operation when mixed signaling technologies are present on the same bus segment.

Replacement Considerations

The DS2120E is a pin-compatible alternative available in a 28-pin TSSOP package. Verify that the target PCB layout accommodates the different package dimensions before substitution.