Texas Instruments SN74LVC240ADWR

Overview

SN74LVC240ADWR from Texas Instruments is an octal noninverting buffer/driver with dual 3-state output banks, operating from 1.65V to 3.6V supply, supporting 5.5V-tolerant inputs, delivering ≤6.5ns propagation delay at 3.3V, and enabling mixed-mode signal interfacing (e.g., 5V logic driving 3.3V bus). It is used in digital signal redriving, transmission line termination, and controller reset hold applications.

For engineers reviewing the SN74LVC240ADWR datasheet, SN74LVC240ADWR pinout, SN74LVC240ADWR application, or SN74LVC240ADWR equivalent, key selection criteria include VCC range compatibility, 3-state bank control timing, Ioff-enabled live insertion support, overvoltage-tolerant input handling, and thermal performance in TSSOP-20 packaging.

Technical Context

The SN74LVC240ADWR implements two independent 4-channel banks (Bank 1: pins 1A1–1A4 / 1Y1–1Y4; Bank 2: pins 2A1–2A4 / 2Y1–2Y4), each controlled by its own active-low output enable (1OE on pin 1, 2OE on pin 19). Its CMOS architecture enables balanced sourcing/sinking (±24mA at 3V) and supports partial power-down via Ioff, which limits leakage to ±10μA when VCC = 0V.

It features Schmitt-trigger–free standard CMOS inputs with 4pF typical input capacitance and 5.5V absolute maximum input voltage - allowing direct interface with 5V systems while powered from 3.3V or lower. Output ground bounce (VOLP < 0.8V) and undershoot (VOHV > 2V) are characterized at 3.3V/25°C for signal integrity assurance.

Key Specifications

Pinout & Package

SN74LVC240ADWR is supplied in a 20-pin TSSOP package (PW suffix), measuring 6.5mm × 6.4mm overall with a 6.5mm × 4.4mm body size. The package includes a thermal pad (pin 20 is VCC; no dedicated thermal pad pin - pad is internal and typically connected to GND).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal buffer applications.

Compared with SN74LVC240APW and 74LVC240ADB, the SN74LVC240ADWR offers identical functionality in a standard TSSOP-20 tape-and-reel configuration optimized for high-volume SMT placement, with marginally better thermal resistance than SSOP and guaranteed packaging compliance for automated pick-and-place.

Availability

SN74LVC240ADWR is available at Aetrix Electronics and suitable for industrial bus redriving, controller reset hold circuits, LED indicator driving, and transmission line termination requiring stable component supply and long-term manufacturability.

Supply support for SN74LVC240ADWR 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 logic solutions, with over 50 years of innovation in high-reliability digital interface ICs.

The SN74LVC240ADWR belongs to TI's LVC (Low-Voltage CMOS) logic family, designed specifically for low-voltage, high-speed, mixed-signal interfacing in space-constrained industrial and automotive control systems.

FAQ

What is the function of the two output enable pins on the SN74LVC240ADWR?

The SN74LVC240ADWR has two independent active-low output enable pins: 1OE (pin 1) controls Bank 1 outputs (1Y1–1Y4), and 2OE (pin 19) controls Bank 2 outputs (2Y1–2Y4). When either OE is low, its associated four outputs drive their respective inputs; when high, those outputs enter high-impedance state. This allows selective bus isolation - for example, holding one peripheral subsystem in reset while communicating with another. Both OEs must be pulled high (e.g., via 10kΩ resistor to VCC) to ensure defined state at power-up.

Can the SN74LVC240ADWR safely interface a 5V microcontroller with a 3.3V FPGA?

Yes. The SN74LVC240ADWR accepts input voltages up to 5.5V while operating from a 3.3V VCC supply, enabling direct connection from 5V logic outputs to its A-inputs. Its outputs swing rail-to-rail (0V to 3.3V), making them compatible with 3.3V FPGA I/O. No external level shifters are needed - this mixed-mode capability is explicitly supported per datasheet Section 1 and Recommended Operating Conditions.

What is the maximum capacitive load the SN74LVC240ADWR can drive while maintaining specified timing?

The SN74LVC240ADWR is characterized to meet all timing specifications (e.g., 6.5ns tpd) with a 50pF load, as stated in Section 8.2.1.1. Larger capacitive loads may be driven, but propagation delay increases and signal integrity degrades - especially beyond 100pF. For reliable operation within datasheet limits, keep total load capacitance ≤50pF. Layout best practices (short traces, ground plane) help maintain performance near this limit.

Does the SN74LVC240ADWR support hot-plug or live-insertion applications?

Yes. The SN74LVC240ADWR includes Ioff circuitry that disables all outputs and limits leakage to ±10μA when VCC = 0V, preventing back-drive current flow from powered downstream circuits into the unpowered device. This feature, confirmed in Section 1 and Electrical Characteristics, makes it suitable for hot-plug applications such as modular backplanes or field-replaceable I/O cards where connectors mate while system power remains active.

How should unused inputs be terminated on the SN74LVC240ADWR?

All unused inputs on the SN74LVC240ADWR must be terminated to a valid logic level - either VCC or GND - to prevent floating nodes, oscillation, and excess power consumption. TI recommends a 10kΩ pull-up or pull-down resistor (Section 7.3.3 and 8.2.1.2). Direct connection is acceptable if the signal source is permanently removed; resistor termination is preferred when inputs may be driven intermittently, ensuring stable VIH/VIL margins across temperature and process variation.