Analog Devices Inc./Maxim Integrated DS2119ME+

Overview

DS2119ME+ from Maxim Integrated is an Ultra3 multimode SCSI terminator supporting both low-voltage differential (LVD) and single-ended (SE) bus configurations, featuring auto-sensing of DIFFSENS voltage to select termination mode, 110Ω SE resistance with ±5% tolerance, 105Ω differential impedance in LVD mode, and thermal shutdown protection. It enables backward-compatible SCSI-3/4 bus designs in storage subsystems and server backplanes.

For engineers reviewing the DS2119ME+ datasheet, DS2119ME+ pinout, DS2119ME+ application, or DS2119ME+ equivalent, key selection criteria include DIFFSENSE trinary detection logic, dual-reference voltage generation (1.25V/LVD and 2.85V/SE), ISO-controlled bus isolation, TPWR-supplied termination power handling (2.7–5.5V), and compliance with SPI-2 through SPI-4 and Ultra160/Ultra320 standards.

Technical Context

The DS2119ME+ implements trinary DIFFSENS decoding using two comparators and a NAND gate to distinguish SE (<0.6V), HVD (2.4V–VTPWR+0.3V), and LVD (0.7–1.9V) bus modes. Its internal bandgap reference feeds dual amplifiers generating 1.25V for LVD and 2.85V for SE termination regulation.

In LVD mode, it uses laser-trimmed resistor strings with two current sources to achieve 105Ω differential and 150Ω common-mode impedance plus 112mV fail-safe bias; in SE mode, it actively pulls signal lines to 2.85V and sinks up to 22mA per line while maintaining 110Ω termination resistance.

Key Specifications

Pinout & Package

DS2119ME+ is housed in a 28-pin TSSOP (0.173" wide) package with exposed heat sink ground pad (pins 6 and 22). Pin functions are validated per Maxim DS2119M datasheet Rev 010406.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS2119ME+, DS2119M offers identical functionality in a non-RoHS package but lacks environmental compliance, while MAX3219ESE+ reduces feature set to SE-only operation-making DS2119ME+ the sole choice for multimode, hot-plug–ready, and RoHS-mandated SCSI infrastructure.

Availability

DS2119ME+ is available at Aetrix Electronics and suitable for SCSI server backplanes, hot-pluggable storage enclosures, and RAID controller add-in cards requiring stable component supply across extended product lifecycles.

Supply support for DS2119ME+ 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

Maxim Integrated (now part of Analog Devices) is a U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, communications, and computing markets.

The DS2119ME+ belongs to Maxim's SCSI interface and termination product line, engineered specifically for robust multimode bus termination in enterprise storage systems requiring SPI-2 through SPI-4 compliance and seamless LVD/SE interoperability.

FAQ

What is the primary function of the DS2119ME+ in a SCSI system?

The DS2119ME+ serves as an auto-sensing multimode SCSI terminator that dynamically selects between low-voltage differential (LVD) and single-ended (SE) termination based on the DIFFSENS line voltage. It ensures signal integrity across Ultra160/Ultra320 buses while maintaining backward compatibility with legacy SE devices. The DS2119ME+ integrates precision resistors, dual reference voltages, and thermal protection to deliver reliable bus termination without manual configuration.

How does the DS2119ME+ determine whether to use LVD or SE termination mode?

The DS2119ME+ determines termination mode by monitoring the SCSI DIFFSENS line voltage through its DIFF_CAP pin. Using internal comparators, it detects three voltage ranges: <0.6V (SE), 0.7–1.9V (LVD), and >2.4V (HVD). When LVD is detected, the DS2119ME+ activates its 105Ω differential termination network with 1.25V reference; when SE is detected, it switches to 110Ω SE termination with 2.85V reference. This decision occurs automatically on power-up and during bus reconfiguration.

Can the DS2119ME+ be used in hot-plug SCSI applications?

Yes, the DS2119ME+ supports SCSI bus hot-plug operations via its ISO (isolation) pin and integrated thermal shutdown. When ISO is asserted high, the DS2119ME+ electrically isolates its RxP/RxN termination pins from the SCSI bus while keeping VREF active-preventing signal contention during drive insertion/removal. Additionally, thermal shutdown at 150°C forces pin isolation and disables VREF, ensuring bus stability during overtemperature events. These features make the DS2119ME+ compliant with SCSI hot-plug specifications.

What are the required external components for proper DS2119ME+ operation?

Proper DS2119ME+ operation requires three critical external components: a 4.7µF capacitor between VREF and GND for reference regulation; a 2.2µF + 0.01µF capacitor pair between each TPWR pin and GND for termination power filtering; and a 0.1µF capacitor on DIFF_CAP for digital noise filtering. All capacitors must be placed as close as possible to their respective pins. No external resistors or RC networks are needed-the DS2119ME+ integrates all termination elements and eliminates legacy DIFFSENS filtering components.

Is the DS2119ME+ pin-compatible with other Maxim SCSI terminators like the DS2119M?

Yes, the DS2119ME+ is pin-compatible and functionally identical to the DS2119M, differing only in RoHS compliance (lead-free plating) and top-marking ("+" suffix). Both share identical pinout, electrical specifications, thermal characteristics, and functional behavior-including DIFFSENSE detection, ISO control, and auto-mode switching. The DS2119ME+ replaces DS2119M in new designs requiring RoHS compliance, with no PCB layout or firmware changes needed.