Texas Instruments SN74LVC240APW

Overview

SN74LVC240A from Texas Instruments is an octal noninverting buffer/driver with 3-state outputs, configured as two independent 4-channel banks each controlled by a dedicated active-low output enable (OE) pin. It operates from 1.65V to 3.6V VCC, supports 5.5V-tolerant inputs, delivers ≤6.5ns propagation delay at 3.3V, and enables mixed-mode signal interfacing (e.g., 5V logic driving into 3.3V system buses). It is used for bus buffering, signal redriving, and transmission-line termination in industrial control and embedded I/O expansion.

For engineers reviewing the SN74LVC240A datasheet, SN74LVC240A pinout, SN74LVC240A application, or SN74LVC240A equivalent, key selection criteria include 3-state timing (ten/tdis), Ioff-enabled live insertion, overvoltage-tolerant inputs, thermal performance in TSSOP-20, and bank-level output control for partial bus isolation.

Technical Context

The SN74LVC240A implements dual-bank CMOS buffer architecture with separate OE1/OE2 controls - each enabling four noninverting outputs (Y1–Y4 per bank) while accepting corresponding A1–A4 inputs. Its balanced push-pull outputs drive high/low states symmetrically and enter high-impedance when OE is high, supporting bidirectional bus arbitration.

It features Ioff circuitry that disables all outputs when VCC = 0V, preventing back-drive current during partial power-down, and includes Schmitt-trigger–free standard CMOS inputs with 4pF input capacitance and ±5μA leakage at 3.6V. Input voltage tolerance up to 5.5V enables safe interfacing with higher-voltage logic families without level shifters.

Key Specifications

Pinout & Package

PW package is a 20-pin Thin Shrink Small Outline Package (TSSOP) with 0.65mm pitch, 6.5mm × 6.4mm overall footprint, and 6.5mm × 4.4mm body size. Thermal pad is absent - no exposed pad grounding required.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC240APW, SN74LVC244APW sacrifices bank-level isolation for simpler control, while 74LVC240ADTR2G offers identical functionality in a mechanically distinct TSSOP variant - both require careful review of OE architecture and package land pattern before substitution.

Availability

SN74LVC240A is available at Aetrix Electronics and suitable for industrial bus buffering, embedded I/O expansion, transmission-line redriving, and controller reset hold applications requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for SN74LVC240A 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 decades of expertise in high-reliability industrial and automotive IC design.

The SN74LVC240A belongs to TI's LVC (Low-Voltage CMOS) logic family, engineered for low-voltage operation (1.65–3.6V), mixed-signal interoperability, and robust noise immunity in space- and power-constrained embedded systems.

FAQ

What is the maximum operating temperature range for the SN74LVC240A?

The SN74LVC240A is specified for operation from –40°C to +125°C ambient temperature. This extended range is validated per JEDEC JESD78 and supports deployment in industrial control cabinets, automotive engine compartments, and outdoor equipment enclosures where thermal cycling and sustained high temperatures occur. The SN74LVC240A maintains full electrical compliance across this range, including tpd ≤6.9ns at 125°C and VCC = 3.3V.

Does the SN74LVC240A support 5V input signals when powered at 3.3V?

Yes, the SN74LVC240A accepts input voltages up to 5.5V regardless of VCC level - a feature explicitly documented in its Recommended Operating Conditions table. When VCC = 3.3V, inputs at 5V are safely clamped and interpreted as valid HIGH logic levels without damage or functional degradation. This eliminates external level-shifting components in mixed-voltage systems, and the SN74LVC240A retains full timing and drive specifications under this condition.

How does the Ioff feature of the SN74LVC240A protect during live insertion?

The Ioff feature in the SN74LVC240A disables all outputs when VCC = 0V, limiting leakage current to ±10μA maximum even if input or output pins are driven externally. During live insertion, this prevents back-driving current from powered backplane traces into unpowered circuitry, avoiding latch-up, data corruption, or thermal overstress. The SN74LVC240A's Ioff behavior is tested per JESD78 and ensures safe hot-swap compliance without requiring external isolation circuitry.

Can the SN74LVC240A drive a 50pF load while meeting datasheet timing specs?

Yes - the SN74LVC240A is characterized and guaranteed to meet all switching specifications (including tpd ≤6.5ns and ten ≤8ns at 3.3V) with a 50pF capacitive load, as defined in TI's Load Circuit (Figure 6-1). Exceeding 50pF increases propagation delay and may degrade edge rates; for heavier loads, derating curves in Figure 5-1 show tpd increases to ~7.5ns at 100pF. The SN74LVC240A's Cpd = 32pF at 3.3V further confirms its suitability for moderate-capacitance bus environments.

What is the recommended bypass capacitor for the SN74LVC240A?

A 0.1μF ceramic capacitor placed as close as possible to the VCC pin (Pin 20) and connected to the nearest GND pin (Pin 10) is the minimum recommended bypass solution for the SN74LVC240A. TI's Layout Guidelines (Section 8.4.1) specify short, wide traces and placement on the same PCB layer to minimize inductance. For enhanced noise suppression across frequency bands, a parallel 1μF capacitor is advised - both values are validated in TI's reference layouts (Figures 8-4 through 8-6) and ensure stable operation under fast-switching conditions.