Texas Instruments DS26C31TM/NOPB

Overview

DS26C31TM/NOPB from Texas Instruments (formerly National Semiconductor) is a CMOS quad differential line driver for RS-422 digital data transmission over balanced lines. It operates from a single 5V supply, delivers 2.5–3.4V high-level output voltage at −20 mA load, achieves 6 ns typical propagation delay, and features TRI-STATE® outputs with common enable/disable control. It is used in industrial serial interfaces requiring low-power, high-speed, bus-compatible differential signaling.

For engineers reviewing the DS26C31TM/NOPB datasheet, DS26C31TM/NOPB pinout, DS26C31TM/NOPB application, or DS26C31TM/NOPB equivalent, key selection criteria include RS-422 compliance level (T vs M variant), −55°C to +125°C extended temperature operation, 0.5 ns typical output skew, and SOIC-16 surface-mount package compatibility with legacy AM26LS31/DS26LS31 layouts.

Technical Context

The DS26C31TM/NOPB implements four independent CMOS-based differential drivers with TTL/CMOS-compatible inputs and RS-422-compliant differential outputs. Its output stage uses special circuitry enabling true bus-isolation during power-down (VCC = 0V), preventing line loading. All four drivers share a common active-low ENABLE and active-high ENABLE input pair for synchronized TRI-STATE control.

It meets EIA RS-422 requirements for differential output voltage (≥2.0 V into 100 Ω), common-mode output range (1.8–3.0 V), and skew (≤2.0 ns max), with DS26C31T fully compliant and DS26C31M meeting RS-422 except for test methodology on output voltage limits (Note 8). Input protection includes diodes to VCC and ground.

Key Specifications

Pinout & Package

DS26C31TM/NOPB is supplied in a 16-pin SOIC (Small Outline Integrated Circuit) package, NS Package Number M16A, surface-mount compatible with standard reflow profiles and IPC-7351 land patterns.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar differential line driver applications.

Compared with AM26LS31CDR and SN65LBC179DR, DS26C31TM/NOPB uniquely combines quad integration, 0.5 ns skew, VCC = 0V bus isolation, and −55°C to +125°C operation - making it optimal for space-constrained, high-reliability, multi-channel RS-422 links where timing coherence and power-down safety are mandatory.

Availability

DS26C31TM/NOPB is available at Aetrix Electronics and suitable for industrial serial interfaces, motor control feedback links, avionics data bus nodes, and ruggedized test equipment interfaces requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for DS26C31TM/NOPB 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

Texas Instruments acquired National Semiconductor in 2011 and maintains its precision analog and interface product portfolio, including legacy RS-422/RS-485 drivers engineered for reliability and interoperability.

The DS26C31TM/NOPB belongs to National's legacy CMOS line driver family, designed specifically for high-speed, low-power, multi-channel differential signaling in industrial, aerospace, and instrumentation systems demanding strict timing and bus-safety behavior.

FAQ

What is the RS-422 compliance status of DS26C31TM/NOPB?

The DS26C31TM/NOPB is the DS26C31M variant, which is RS-422 compatible but tested with a modified output voltage condition (0V to +6V instead of −0.25V to +6V per RS-422A). This deviation does not affect functional interoperability in real-world balanced-line applications and is documented in Note 8 of the datasheet. DS26C31TM/NOPB retains full electrical compatibility with RS-422 receivers.

Does DS26C31TM/NOPB support true bus-isolation when powered down?

Yes. DS26C31TM/NOPB features bus-isolating outputs: when VCC = 0V, all outputs enter high-impedance state without loading the differential bus. This is confirmed by IOFF leakage current ≤±100 µA at VOUT = 0V and VCC = 0V (DC Electrical Characteristics table), enabling safe hot-swap and fail-safe operation in multi-node RS-422 networks.

What is the maximum data rate supported by DS26C31TM/NOPB?

DS26C31TM/NOPB supports data rates up to approximately 70 Mbps, derived from its 6 ns typical propagation delay and 14 ns maximum delay (tPLH/tPHL), combined with 0.5 ns typical output skew ensuring inter-pair timing integrity. Actual achievable rate depends on cable length, termination, and noise; for 10-meter twisted-pair, 10–20 Mbps is reliably attainable per channel.

Is DS26C31TM/NOPB pin-compatible with older bipolar line drivers?

Yes. DS26C31TM/NOPB is explicitly pin-compatible with AM26LS31 and DS26LS31, sharing identical SOIC-16 pinout and signal mapping (inputs on pins 1–2, 4–5, 7–8, 10–11; outputs on pins 3, 6, 9, 12, 13–16; enables on pins 17–18). This allows drop-in replacement in existing designs to upgrade from bipolar to CMOS performance without PCB changes.

What package type and RoHS status does DS26C31TM/NOPB use?

DS26C31TM/NOPB is supplied in a 16-pin SOIC package (NS Package Number M16A) with gull-wing leads, and is RoHS-compliant (Pb-free, halogen-free). The /NOPB suffix confirms lead-free finish per JEDEC J-STD-020, qualified for standard SnPb and Pb-free reflow profiles, with peak temperature rating of 260°C for 4 seconds.