Texas Instruments SN74HCT240PWR

Overview

SN74HCT240PWR from Texas Instruments is an octal inverting buffer/line driver with 3-state outputs, designed for memory address and bus driving in industrial control and embedded systems. It operates at 4.5–5.5 V, delivers ±6 mA output drive, exhibits 12 ns typical propagation delay, and draws ≤80 μA supply current. Its dual 4-bit structure with independent OE inputs enables selective bus isolation in high-density PCB layouts.

For engineers reviewing the SN74HCT240PWR datasheet, SN74HCT240PWR pinout, SN74HCT240PWR application, or SN74HCT240PWR equivalent, key selection criteria include 3-state bus-driving capability, TTL-compatible inputs, 20-pin TSSOP packaging, and guaranteed operation across –40°C to +85°C industrial temperature range.

Technical Context

The SN74HCT240PWR implements two independent 4-bit inverting buffers, each controlled by a dedicated output-enable (OE) input. When OE is low, inverted data passes from A inputs to Y outputs; when OE is high, all eight outputs enter high-impedance state-enabling bidirectional bus sharing without contention.

Its HCT logic family ensures TTL-voltage compatibility (VIH = 2 V, VIL = 0.8 V) while maintaining CMOS power efficiency. Input leakage remains ≤1 μA, and output drive meets LSTTL load requirements (up to 15 loads), making it suitable for legacy system interfacing and mixed-voltage board designs.

Key Specifications

Pinout & Package

TSSOP-20 (PW) package: 6.50 mm × 6.40 mm body, 1.2 mm max height, 0.65 mm lead pitch, exposed thermal pad optional per SLMA002/SLMA004 guidelines.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCT240DWR and 74HCT240PW,118, the SN74HCT240PWR offers optimal balance of compact TSSOP footprint, best-in-class 12 ns propagation delay, and TI's long-term industrial supply commitment-making it preferred for new high-density embedded designs requiring timing precision and lifecycle stability.

Availability

SN74HCT240PWR is available at Aetrix Electronics and suitable for industrial control systems, programmable logic controllers, and embedded memory subsystems requiring stable component supply across multi-year production cycles.

Supply support for SN74HCT240PWR 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 for industrial, automotive, and communications markets.

The SN74HCT240PWR belongs to TI's 74HCT logic family, engineered for TTL-compatible interfacing in industrial control, memory expansion, and bus management applications where reliability and long-term availability are critical.

FAQ

What is the maximum operating temperature for SN74HCT240PWR?

The SN74HCT240PWR is rated for continuous operation from –40°C to +85°C ambient temperature. This industrial-grade specification ensures reliable performance in factory automation panels, outdoor kiosks, and other environments lacking active thermal management. The TSSOP package's thermal resistance (RθJA = 131.8°C/W) requires attention to PCB copper area and airflow in high-power-density layouts.

Does SN74HCT240PWR require external pull-up resistors on its outputs?

No, SN74HCT240PWR does not require external pull-up resistors on its outputs when used in 3-state mode. Its outputs are actively driven high or low during enabled states and present high impedance (IOZ ≤ ±5 μA) when disabled. Pull-ups are only needed if open-drain emulation is required-a function not supported by this device's push-pull 3-state architecture.

Can SN74HCT240PWR interface directly with 3.3 V microcontrollers?

Yes, SN74HCT240PWR inputs are TTL-voltage compatible (VIH ≥ 2.0 V, VIL ≤ 0.8 V), so 3.3 V logic high from most microcontrollers exceeds the 2.0 V VIH threshold. However, its outputs swing rail-to-rail (0 V to 5 V), so connecting to 3.3 V-only inputs requires series resistors or level translators to avoid overvoltage damage-SN74HCT240PWR itself does not provide level shifting.

What is the purpose of the two separate OE pins on SN74HCT240PWR?

The two independent output-enable pins (1OE on pin 1, 2OE on pin 19) allow selective control of the two internal 4-bit buffer groups. This enables partial bus isolation-for example, holding memory address lines active while tri-stating peripheral control signals during interrupt servicing. It eliminates the need for additional logic gates or software overhead to manage grouped enable functions.

Is SN74HCT240PWR pin-compatible with SN74LS240?

SN74HCT240PWR is functionally identical to SN74LS240 but not pin-compatible due to differing package types: SN74LS240 is typically offered in PDIP or SOIC, while SN74HCT240PWR uses TSSOP-20. Electrical pin functions match (e.g., 1OE, A1–A4, Y1–Y4), but physical layout, thermal pad presence, and lead pitch differ. Migration requires PCB redesign unless using adapter boards or SOIC-to-TSSOP carriers.