Texas Instruments SN74AHCT240PWRG4

Overview

SN74AHCT240PWRG4 from Texas Instruments is an octal inverting buffer/driver with tri-state outputs, designed for bus-oriented receivers and transmitters in 5-V systems. It features TTL-compatible inputs (VIH = 2 V, VIL = 0.8 V), ±8 mA output drive, 9.5 ns max propagation delay at 5 V/50 pF, and operates from –40°C to +125°C. It enables level translation from 3.3-V logic to 5-V buses in network switches and industrial control interfaces.

For engineers reviewing the SN74AHCT240PWRG4 datasheet, SN74AHCT240PWRG4 pinout, SN74AHCT240PWRG4 application, or SN74AHCT240PWRG4 equivalent, key selection criteria include its dual 4-bit inverting tri-state architecture, TSSOP-20 package compatibility, guaranteed 5-V operation with 3.3-V input tolerance, and low-noise slow-edge output drivers suitable for noise-sensitive bus environments.

Technical Context

The SN74AHCT240PWRG4 implements two independent 4-bit inverting buffer sections, each with dedicated output-enable (OE) control. Each section passes inverted data from A inputs to Y outputs when OE is low; outputs enter high-impedance state when OE is high. The device uses CMOS circuitry optimized for 5-V supply but accepts 3.3-V TTL-level inputs without level shifters.

Its electrical behavior is defined by strict VIH/VIL thresholds (2 V / 0.8 V), rail-to-rail output swing (VOH ≥ 3.8 V at –8 mA, VOL ≤ 0.44 V at 8 mA), and controlled edge rates that suppress ringing on lightly loaded buses. Thermal performance is characterized by RθJA = 116.8°C/W in its PW (TSSOP-20) package, supporting industrial temperature operation up to +125°C.

Key Specifications

Pinout & Package

TSSOP-20 (PW) package: 6.50 mm × 6.40 mm body size, 0.65 mm lead pitch, thin-profile surface-mount construction suitable for high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AHCT240PW (obsolete) and 74LVC240APW (3.3-V-only), SN74AHCT240PWRG4 uniquely delivers verified 3.3-V-to-5-V translation, industrial temperature support, and active manufacturing status - making it the sole fit for new 5-V bus interface designs requiring mixed-voltage interoperability.

Availability

SN74AHCT240PWRG4 is available at Aetrix Electronics and suitable for network switches, industrial PLC backplanes, medical imaging control buses, and smart energy meter interfaces requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for SN74AHCT240PWRG4 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 delivering analog and embedded processing solutions, with over 90 years of innovation in logic, power management, and signal chain technologies.

SN74AHCT240PWRG4 belongs to the SNx4AHCT advanced high-speed CMOS logic family, engineered specifically for robust 5-V bus interfacing, level translation, and noise-immune tri-state control in industrial, automotive, and communications infrastructure.

FAQ

What is the maximum output current per pin for SN74AHCT240PWRG4?

The SN74AHCT240PWRG4 supports ±8 mA DC output current per pin under recommended operating conditions (VCC = 4.5 V to 5.5 V). This value is specified in the Electrical Characteristics table for both IOH and IOL test conditions. Exceeding this limit risks violating absolute maximum ratings and may degrade long-term reliability or cause bus contention in multi-driver configurations. The total device supply current must remain within ±75 mA.

Does SN74AHCT240PWRG4 support 3.3-V input signals when powered at 5 V?

Yes, SN74AHCT240PWRG4 explicitly supports 3.3-V TTL-level inputs at 5-V VCC. Its VIH threshold is guaranteed at 2.0 V minimum and VIL at 0.8 V maximum across –40°C to +125°C, allowing direct connection to 3.3-V logic families without external biasing or level-shifting circuitry. This capability is confirmed in Section 5.3 (Recommended Operating Conditions) and Feature Description.

What is the function of the OE pins on SN74AHCT240PWRG4?

SN74AHCT240PWRG4 has two active-low output-enable pins: 1OE (Pin 1) controls outputs 1Y1–1Y4, and 2OE (Pin 19) controls outputs 2Y1–2Y4. When an OE pin is low, its corresponding 4-bit group passes inverted input data to outputs; when high, those outputs enter high-impedance state. To prevent undefined states at power-up, TI recommends tying OE pins to VCC via a pull-up resistor.

Is SN74AHCT240PWRG4 pin-compatible with other packages of the same part number?

Yes, SN74AHCT240PWRG4 shares identical pinout and functionality with all other SN74AHCT240 variants (e.g., DB, DW, NS, N packages), as confirmed in the Pin Configuration and Functions section of the datasheet. All 20-pin versions use the same signal assignment and electrical behavior - only mechanical dimensions and thermal characteristics differ. Layout migration between PW and DW packages requires trace routing adjustment but no netlist change.

What is the thermal resistance (RθJA) of SN74AHCT240PWRG4 in its TSSOP package?

The junction-to-ambient thermal resistance (RθJA) for SN74AHCT240PWRG4 in the PW (TSSOP-20) package is 116.8°C/W, as specified in Section 5.4 (Thermal Information). This value assumes standard JEDEC high-K board conditions and is critical for calculating maximum allowable power dissipation at elevated ambient temperatures - for example, limiting ICC to ~6.4 mA at +125°C ambient to stay below 150°C junction temperature.