Analog Devices Inc./Maxim Integrated DS2119M/T&R

Overview

DS2119M/T&R 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, and integrated thermal shutdown. It is used in wide SCSI backplanes requiring hot-plug-compatible active termination.

For engineers reviewing the DS2119M/T&R datasheet, DS2119M/T&R pinout, DS2119M/T&R application, or DS2119M/T&R equivalent, key selection criteria include LVD/SE mode auto-detection via DIFFSENSE logic, 28-pin TSSOP package compatibility, 105Ω differential / 150Ω common-mode impedance in LVD mode, and support for Ultra160/Ultra320 timing compliance.

Technical Context

The DS2119M/T&R implements trinary DIFFSENS decoding using two comparators and a NAND gate to distinguish SE (<0.6V), HVD (2.4V–VTPWR+0.3V), and LVD (0.7V–1.9V) bus conditions. Its internal bandgap reference generates 1.25V for LVD mode and 2.85V for SE mode, switching precision resistor strings and current sources accordingly.

In LVD mode, it delivers 105Ω differential and 150Ω common-mode termination with 112mV fail-safe bias; in SE mode, it maintains 110Ω termination while sourcing 25.4mA per line and regulating at 2.85V ±0.15V. Thermal shutdown activates at 150°C, isolating RxP/RxN pins and disabling VREF and DIFFSENSE driver.

Key Specifications

Pinout & Package

DS2119M/T&R 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+T&R, DS2119M/T&R offers identical performance but without lead-free finish; compared with MAX3221EESA+, DS2119M/T&R provides dedicated SCSI multimode termination with auto-sensing, whereas MAX3221EESA+ serves entirely different interface standards and cannot substitute.

Availability

DS2119M/T&R is available at Aetrix Electronics and suitable for SCSI wide backplane termination, Ultra320 RAID controller interfaces, and legacy server storage expansion requiring stable component supply and long-term industrial availability.

Supply support for DS2119M/T&R 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 analog, mixed-signal, and power management ICs for industrial, communications, and computing applications.

The DS2119M/T&R belongs to Maxim's SCSI interface product line, engineered specifically for robust, self-adapting parallel SCSI termination in mission-critical storage systems with mixed-generation device fleets.

FAQ

What termination modes does the DS2119M/T&R support?

The DS2119M/T&R supports three operational modes: low-voltage differential (LVD), single-ended (SE), and HVD isolation. It automatically selects LVD or SE based on the voltage detected on the DIFFSENS line - below 0.6V triggers SE mode, 0.7V–1.9V selects LVD mode, and above 2.4V initiates HVD isolation. This behavior is confirmed in the functional description and DIFFSENS operating range specifications of the DS2119M datasheet Rev 010406.

How does the DS2119M/T&R handle thermal overload?

When junction temperature reaches 150°C, the DS2119M/T&R activates thermal shutdown: it isolates all RxP/RxN termination pins from the SCSI bus, places VREF in high-impedance state, and disables the DIFFSENSE driver. This prevents bus corruption and protects downstream devices. The shutdown threshold is guaranteed by design and documented in the DC characteristics table on page 7 of the DS2119M datasheet.

Is the DS2119M/T&R pin-compatible with the DS2119ME+T&R?

Yes, the DS2119M/T&R is pin-compatible with the DS2119ME+T&R. Both share identical 28-pin TSSOP packaging, pinout, electrical specifications, and functional behavior. The sole difference is that DS2119ME+T&R uses a lead-free/RoHS-compliant finish, indicated by a "+" top mark. This compatibility is explicitly stated in the ordering information table on page 1 of the DS2119M datasheet.

What external components are required for stable DS2119M/T&R operation?

The DS2119M/T&R requires three mandatory external components: a 4.7µF capacitor between VREF and GND for reference regulation; a 2.2µF capacitor plus 0.01µF ceramic capacitor between each TPWR pin and GND for power rail decoupling; and a 0.1µF capacitor on DIFF_CAP for digital noise filtering. These values are specified in the "Recommended Operating Conditions" and "Capacitor Requirements" sections of the DS2119M datasheet Rev 010406.

Can the DS2119M/T&R be used as the sole terminator on a wide SCSI bus?

No, three DS2119M/T&R units are required for full termination of a wide (16-bit) SCSI bus. Each DS2119M/T&R terminates nine signal line pairs, and a wide SCSI bus has 18 signal lines (nine differential pairs). This requirement is explicitly stated in the Detailed Description section on page 1 of the DS2119M datasheet: "Three DS2119M terminators are needed for a wide SCSI bus."