Texas Instruments SN74ACT240PWRG4

Overview

SN74ACT240PWRG4 from Texas Instruments is an octal 3-state inverting buffer/driver IC designed for bus-oriented data transmission, clock distribution, and memory address driving in high-density digital systems. It operates from 4.5 V to 5.5 V, supports TTL-compatible inputs up to 5.5 V, delivers ≤8.5 ns propagation delay at 5 V, and features balanced CMOS push-pull outputs capable of ±24 mA drive per channel - used in smartphone handset interfaces and network switch backplanes.

For engineers reviewing the SN74ACT240PWRG4 datasheet, SN74ACT240PWRG4 pinout, SN74ACT240PWRG4 application, or SN74ACT240PWRG4 equivalent, key selection criteria include its dual 4-bit inverting architecture with independent output-enable controls, TSSOP-20 package compatibility with space-constrained PCB layouts, thermal performance under sustained 24 mA loads, and interoperability with 5-V TTL and CMOS logic families.

Technical Context

The SN74ACT240PWRG4 implements two independent 4-bit inverting buffer sections (1A→1Y and 2A→2Y), each controlled by a dedicated active-low output-enable input (1OE, 2OE). When OE is low, data passes inverted from A inputs to Y outputs; when high, outputs enter high-impedance state - enabling bidirectional bus control without external direction logic.

Its balanced CMOS push-pull outputs provide symmetrical sourcing/sinking capability (±24 mA), ensuring clean signal edges into light capacitive loads. Input voltage tolerance extends to 5.5 V regardless of VCC, allowing mixed-voltage interfacing with legacy 5-V systems while operating on regulated 5-V rails.

Key Specifications

Pinout & Package

TSSOP-20 (PW) package: 6.5 mm × 6.4 mm body size, 1.2 mm max height, 0.65 mm lead pitch, exposed thermal pad (not electrically connected by default).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal 3-state inverting buffer applications.

Compared with SN74ACT240PW and SN74LVC240APWR, SN74ACT240PWRG4 uniquely combines 5-V TTL compatibility, industrial temperature range, RoHS compliance, and active production status - making it the sole viable option for new 5-V bus-buffering designs requiring supply-chain continuity.

Availability

SN74ACT240PWRG4 is available at Aetrix Electronics and suitable for smartphone handset interfaces, network switch backplanes, and wearable health sensor hubs requiring stable component supply across multi-year production cycles.

Supply support for SN74ACT240PWRG4 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 SNx4ACT240 family was engineered for high-speed, low-skew bus driving in memory subsystems and clock distribution networks - prioritizing timing precision, noise immunity, and mixed-voltage interoperability in dense PCB layouts.

FAQ

What is the function of the two OE pins on SN74ACT240PWRG4?

The SN74ACT240PWRG4 has two independent active-low output-enable inputs: 1OE controls Y1–Y4 (first 4-bit group), and 2OE controls Y1–Y4 (second 4-bit group). When an OE pin is low, its corresponding outputs invert and pass A-input data; when high, those outputs enter high-impedance state. This enables selective bus arbitration without external logic, and tying OE to V_CC via pullup ensures safe high-Z during power-up.

Does SN74ACT240PWRG4 support 3.3-V input logic levels?

SN74ACT240PWRG4 does not guarantee reliable operation with 3.3-V inputs. Its specified V_IL is 0.8 V and V_IH is 2.0 V at V_CC = 5 V, meaning it requires TTL-compatible thresholds. A 3.3-V logic high may fall below the 2.0-V minimum V_IH, risking misinterpretation. For 3.3-V systems, use SN74LVC240APWR instead - but note it lacks 5-V tolerance.

Can SN74ACT240PWRG4 drive a 50-Ω transmission line directly?

Yes, SN74ACT240PWRG4 can drive a 50-Ω transmission line directly due to its ±24 mA output drive strength and fast edge rates. At 5 V, sourcing 24 mA into 50 Ω yields ~1.2 V drop, leaving ~3.8 V swing - sufficient for TTL-compatible receivers. However, series termination (e.g., 33 Ω) is recommended to dampen reflections, especially for trace lengths >5 cm.

What is the purpose of the exposed thermal pad on the SN74ACT240PWRG4 TSSOP package?

The exposed thermal pad on SN74ACT240PWRG4's TSSOP-20 package improves heat dissipation from the silicon die to the PCB. Though electrically isolated by default, TI recommends connecting it to the system GND plane using multiple vias to reduce junction-to-ambient thermal resistance by >10%. This enhances reliability under sustained 24 mA per-output loading and prevents thermal throttling in compact layouts.

Is SN74ACT240PWRG4 pin-compatible with other packages in the SN74ACT240 family?

Yes, SN74ACT240PWRG4 shares identical pinout and functionality with all SN74ACT240 variants in SOIC (DW), SSOP (DB), VSSOP (DGS), PDIP (N), SOP (NS), and VQFN (RKS) packages. The TSSOP-20 (PW) footprint matches JEDEC MO-153, and logic functions, pin numbering, and signal roles (e.g., Pin 1 = 1OE, Pin 2 = 1A1) are fully consistent across all package types - enabling drop-in replacement based on board space and thermal needs.