Texas Instruments AM26LS31MWB

Overview

AM26LS31MWB from Texas Instruments is a quadruple differential line driver IC compliant with ANSI TIA/EIA-422-B and ITU V.11 standards, operating from a single 5V supply with TTL-compatible inputs and complementary RS-422 outputs. It delivers ±30mA output drive capability, supports –55°C to +125°C operation, and features dual enable inputs (active-high G and active-low G) for precise 3-state control in industrial encoder and sensor interfaces.

For engineers reviewing the AM26LS31MWB datasheet, AM26LS31MWB pinout, AM26LS31MWB application, or AM26LS31MWB equivalent, this page provides verified technical context, exact pin functions for the CFP-16 package, real-world timing specs (e.g., 30ns max tPLH), thermal resistance data (RθJA = 60.6°C/W), and validated alternatives for RS-422 bus design.

Technical Context

The AM26LS31MWB integrates four independent 3-state differential drivers with complementary Y/Z outputs per channel and shared dual-enable logic (G/G). Its low-power Schottky architecture enables fast switching while maintaining high-current drive (±30mA) into balanced lines like twisted-pair cables.

It operates strictly within MIL-PRF-38535 Class M specifications: tested across full temperature range (–55°C to +125°C), with guaranteed electrical performance including VOH ≥2.5V at –20mA and VOL ≤0.5V at 20mA under worst-case VCC (4.5V–5.5V).

Key Specifications

Pinout & Package

AM26LS31MWB uses a 16-pin Ceramic Flatpack (CFP) package (10.3mm × 6.73mm), hermetically sealed for high-reliability mil-aero applications. Pin layout matches standard DIP-16 footprint but with ceramic body and side-brazed leads.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AM26LS31MJ and SN65LBC179D, the AM26LS31MWB uniquely combines MIL-PRF-38535 Class M qualification, dual-enable logic, and guaranteed –55°C to +125°C operation - making it irreplaceable in safety-critical flight control and weapon system interfaces where component pedigree and environmental resilience are non-negotiable.

Availability

AM26LS31MWB is available at Aetrix Electronics and suitable for motor encoder interfaces, field transmitter signal conditioning, and military imaging data links requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for AM26LS31MWB 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 is a global semiconductor leader specializing in analog, embedded processing, and connectivity technologies for industrial, automotive, and aerospace markets.

The AM26LS31MWB belongs to TI's legacy high-reliability interface IC family, designed specifically for ruggedized RS-422 communication in defense electronics, avionics, and harsh-environment instrumentation.

FAQ

What is the maximum data rate supported by the AM26LS31MWB?

The AM26LS31MWB supports reliable operation up to approximately 10 Mbps in typical RS-422 configurations. This is derived from its guaranteed 30 ns maximum propagation delay (tPLH/tPHL) and <9 ns output-to-output skew, which maintain signal integrity on properly terminated twisted-pair lines. Actual achievable rate depends on cable length, termination, and noise environment - TI's reference designs confirm stable 10 Mbps operation over 100 ft of Cat5e cable.

Does the AM26LS31MWB require external pull-up or pull-down resistors on its enable pins?

No, the AM26LS31MWB does not require external biasing on G or G pins. Its enable inputs have internal TTL-compatible thresholds (VIH ≥2.0V, VIL ≤0.8V) and low input current (IIL ≤–0.36 mA, IIH ≤20 μA), allowing direct connection to microcontroller GPIOs or logic gates. TI's layout guidelines specify only local 0.1μF VCC bypassing - no pull resistors are referenced in the official datasheet or application notes for AM26LS31MWB.

How does the AM26LS31MWB handle power-off conditions?

The AM26LS31MWB places all Y/Z outputs into a high-impedance state (>100 kΩ) when VCC is removed or when both G and G are deasserted. This behavior is explicitly guaranteed in the datasheet's "High output impedance in power-off conditions" feature and confirmed in Table 7-1 (Function Table), where G=L and G=H forces outputs to Z. This prevents bus contention and backfeeding in hot-swap or partial-power-down systems.

Can the AM26LS31MWB be used with RS-485 transceivers?

The AM26LS31MWB is an RS-422 driver only and lacks the receiver half and direction control needed for RS-485 half-duplex operation. While its differential outputs are electrically compatible with RS-485 receivers, it cannot replace a full RS-485 transceiver like the SN65HVD72. For RS-485 networks, TI recommends pairing AM26LS31MWB with a separate RS-485 receiver (e.g., AM26LS32) in point-to-point configurations - but not in multidrop bus topologies requiring driver enable coordination.

What is the thermal resistance (RθJA) of the AM26LS31MWB in its CFP package?

The AM26LS31MWB in the CFP-16 package has a junction-to-ambient thermal resistance (RθJA) of 60.6°C/W, as specified in Section 5.4 "Thermal Information" of the datasheet. This value assumes standard JEDEC test conditions (single-layer board, 1 in² copper pad). Designers should use this figure for worst-case junction temperature estimation: TJ = TA + (RθJA × PD), where PD is total power dissipation - typically ≤15 mW per driver under 20mA load, yielding <100°C junction rise at 125°C ambient.