Analog Devices Inc./Maxim Integrated DS2114Z

Overview

DS2114Z from Dallas Semiconductor is a monolithic SCSI active terminator IC integrating nine laser-trimmed 110 Ω termination resistors, a low-dropout voltage regulator, and thermal shutdown protection in a narrow 16-pin SOIC package. It delivers 2.85 V reference output with ±2% resistor tolerance and supports single-ended SCSI-2/SCSI-3 bus termination at cable ends.

For engineers reviewing the DS2114Z datasheet, DS2114Z pinout, DS2114Z application, or DS2114Z equivalent, key selection considerations include TERMPWR decoupling requirements, VREF1/VREF2 external tie constraints, quiescent current (2.5 mA), and compatibility with 8-bit ("A") and 16-bit ("P") SCSI bus topologies requiring multiple DS2114Z units per end.

Technical Context

The DS2114Z implements a bandgap reference generating 2.55 V, buffered to a stable 2.85 V output capable of sourcing ≥24 mA per termination line and sinking ≥200 mA for actively negated SCSI signals. Its internal architecture ensures <60 mV VREF shift under sink load and integrates thermal shutdown activation at 150°C.

It operates from 4.0–5.5 V TERMPWR input, maintains 110–116 Ω termination resistance across temperature, and requires external 4.7 µF decoupling on VREF pins plus 2.2–4.7 µF on TERMPWR pins-critical for noise immunity and bus stability in high-speed SCSI environments.

Key Specifications

Pinout & Package

Narrow 16-pin plastic SOIC (150 mil), 9.80 mm × 3.81 mm body, 1.27 mm pitch, RoHS-compliant lead finish.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar SCSI termination applications.

Compared with DS2114Z, DS2115Z simplifies layout by embedding the VREF capacitor, while MAX4890ESE+ shifts reference architecture to 3.3 V-making DS2114Z the sole choice for legacy 5 V TERMPWR SCSI-2/SCSI-3 termination with guaranteed 2.85 V regulation and thermal safety.

Availability

DS2114Z is available at Aetrix Electronics and suitable for SCSI-2/SCSI-3 storage subsystems, industrial RAID controllers, and legacy workstation bus termination requiring stable component supply and long-lifecycle support.

Supply support for DS2114Z includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Dallas Semiconductor (now part of Maxim Integrated, a subsidiary of Analog Devices) specializes in precision analog, timing, and interface ICs for industrial and computing applications.

The DS2114Z belongs to Dallas' SCSI interface product line, engineered specifically to replace discrete termination networks with monolithic, standards-compliant active termination for SCSI-2 and SCSI-3 single-ended buses.

FAQ

What is the required external capacitor for DS2114Z VREF pins?

The DS2114Z requires a 4.7 µF tantalum capacitor connected between the VREF1 and VREF2 pins and ground. These pins must also be externally shorted. This capacitor stabilizes the 2.85 V reference output and is mandatory for proper regulation and termination accuracy. Failure to install it results in unstable VREF and unreliable SCSI signal biasing in the DS2114Z.

Can DS2114Z operate with TERMPWR below 4.0 V?

No. The DS2114Z has a specified minimum TERMPWR of 4.0 V per its Recommended Operating Conditions. Operation below this voltage risks insufficient headroom for the internal regulator to maintain 2.85 V output, leading to degraded termination performance and potential SCSI bus errors. The DS2114Z dropout voltage is 0.75 V minimum, so 4.0 V input yields only ~3.25 V worst-case margin-underscoring the 4.0 V floor requirement.

How many DS2114Z devices are needed for a 16-bit SCSI bus?

A 16-bit SCSI ("P") bus requires 27 active signal lines terminated at each end. Since each DS2114Z terminates nine lines, three DS2114Z devices are required per end-totaling six DS2114Z units for full bus termination. This configuration is explicitly documented in the DS2114Z functional description and Figure 2 of the datasheet.

Are pins 10 and 16 on DS2114Z truly unused?

Yes. Pins 10 and 16 are designated NC (No Connect) in the official DS2114Z pin description table. They have no internal connection and must remain unconnected in all designs. Routing traces to or placing components on these pins violates the DS2114Z specification and may cause unintended coupling or mechanical interference in the narrow SOIC package.

Does DS2114Z support actively negated SCSI signals?

Yes. The DS2114Z is explicitly designed to support actively negated SCSI signals: its buffer amplifier can sink ≥200 mA while maintaining VREF shift under 60 mV. This capability ensures correct logic-level interpretation during signal assertion and meets SCSI-2/SCSI-3 specifications for active negation handling-confirmed in the Functional Description section of the DS2114Z datasheet.