Texas Instruments SN74AHCT240PWE4

Overview

SN74AHCT240PWE4 from Texas Instruments is an octal inverting buffer/driver with tri-state outputs, designed for memory-address, clock, and bus-oriented applications. It features TTL-compatible inputs (VIH = 2 V, VIL = 0.8 V), 5-V supply operation (4.5–5.5 V), ±8 mA output drive, 9.5 ns max propagation delay (CL = 50 pF), and operates across –40°C to +125°C. It enables bidirectional bus isolation in industrial control backplanes.

For engineers reviewing the SN74AHCT240PWE4 datasheet, SN74AHCT240PWE4 pinout, SN74AHCT240PWE4 application, or SN74AHCT240PWE4 equivalent, key selection criteria include its 20-pin TSSOP package, dual 4-bit inverting tri-state architecture, 5-V logic compatibility, latch-up immunity (>250 mA), and ESD robustness (±2000 V HBM).

Technical Context

The SN74AHCT240PWE4 integrates two independent 4-bit inverting buffers, each controlled by a dedicated output-enable input (1OE, 2OE). When OE is low, inverted data passes from A inputs to Y outputs; when high, outputs enter high-impedance state - enabling bus sharing without contention.

Its CMOS design with TTL-voltage-compatible inputs allows seamless interfacing between 3.3-V controllers and 5-V legacy buses. Slow edge rates minimize output ringing, and input overvoltage tolerance (up to 5.5 V) supports mixed-voltage system integration without level shifters.

Key Specifications

Pinout & Package

TSSOP-20 (PW) package: 6.50 mm × 6.40 mm body size, 0.65 mm lead pitch, surface-mount, RoHS-compliant, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal inverting tri-state buffer applications.

Compared with SN74AHCT240DWR and 74LVC240APW, SN74AHCT240PWE4 uniquely combines 5-V operation, TTL input compatibility, and compact TSSOP packaging - making it the sole choice for space-constrained industrial upgrades requiring direct 3.3-V-to-5-V interface without redesign.

Availability

SN74AHCT240PWE4 is available at Aetrix Electronics and suitable for industrial backplane bus isolation, automotive body control modules, telecom line card interfaces, and power infrastructure monitoring requiring stable component supply across extended temperature and long-lifecycle programs.

Supply support for SN74AHCT240PWE4 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 industrial, automotive, and communications markets.

The SN74AHCT240PWE4 belongs to TI's AHCT logic family - engineered for 5-V systems requiring TTL compatibility, robust ESD/latch-up performance, and reliable tri-state bus interfacing in harsh environments.

FAQ

What is the maximum operating temperature for SN74AHCT240PWE4?

The SN74AHCT240PWE4 is rated for continuous operation from –40°C to +125°C ambient temperature. This specification is validated per JEDEC JESD22-A108 and applies to the TSSOP-20 (PW) package variant. Thermal derating is not required within this range when used within recommended electrical conditions, including VCC = 4.5–5.5 V and output load ≤8 mA per pin. The device maintains full functionality and timing compliance across the entire range.

Does SN74AHCT240PWE4 support 3.3-V input logic levels?

Yes, SN74AHCT240PWE4 accepts 3.3-V logic inputs reliably due to its TTL-compatible input thresholds: VIH = 2.0 V (min) and VIL = 0.8 V (max). Since 3.3-V CMOS high-level outputs typically exceed 2.7 V, they fully satisfy the VIH requirement. Its inputs are also overvoltage tolerant up to 5.5 V, allowing safe interfacing with mixed-voltage nodes without external protection.

Can SN74AHCT240PWE4 be used as a non-inverting buffer?

No - the SN74AHCT240PWE4 is strictly an inverting octal buffer. Each A input drives a complementary Y output (e.g., 1A1 → 1Y1 with inversion). To achieve non-inverting behavior, two stages must be cascaded, but this adds propagation delay and increases power consumption. For true non-inverting tri-state operation, TI recommends SN74AHCT244PWE4 instead.

What is the recommended bypass capacitor for SN74AHCT240PWE4?

A 0.1 µF X7R ceramic capacitor is recommended directly between VCC (Pin 20) and GND (Pin 10) on the SN74AHCT240PWE4 PCB footprint. Place it within 2 mm of the pins with minimal trace length and width ≥0.3 mm. For systems with multiple logic devices sharing the same 5-V rail, add a bulk 1–10 µF tantalum or aluminum electrolytic capacitor at the power entry point to suppress low-frequency ripple.

Is SN74AHCT240PWE4 pin-compatible with SN74AHCT240PW?

Yes - SN74AHCT240PWE4 is the enhanced-reliability, RoHS-compliant version of SN74AHCT240PW, sharing identical pinout, package dimensions (TSSOP-20), electrical specifications, and functional behavior. The "E4" suffix denotes TI's green packaging standard (lead-free, halogen-free), with no changes to timing, drive strength, or thermal characteristics. Migration requires no PCB or firmware modifications.