Texas Instruments SN74ACT240DWR

Overview

SN74ACT240DWR 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 industrial and consumer systems. It operates from 4.5 V to 5.5 V, delivers ≤8.5 ns propagation delay at 5 V, supports TTL-compatible inputs up to 5.5 V, and features dual independent output-enable controls for flexible bus management in smartphone baseband, network switch backplanes, and wearable sensor hubs.

For engineers reviewing the SN74ACT240DWR datasheet, SN74ACT240DWR pinout, SN74ACT240DWR application, or SN74ACT240DWR equivalent, this page provides verified functional architecture, SOIC-20 package–specific pin mapping, real-world timing and drive specifications, and validated alternative options for high-density 3-state logic interface design.

Technical Context

The SN74ACT240DWR implements two independent 4-bit inverting buffer sections, each with dedicated active-low output-enable (1OE, 2OE) inputs. Its CMOS push-pull outputs provide balanced sourcing/sinking capability (±24 mA), enabling robust signal integrity on shared buses without external pull-ups.

Each section operates with true 3-state control: when OE is low, inverted input-to-output transfer occurs; when OE is high, outputs enter high-impedance mode. Input voltage tolerance extends to 5.5 V regardless of VCC, supporting mixed-voltage interfacing with legacy TTL or 5 V logic families.

Key Specifications

Pinout & Package

SN74ACT240DWR is housed in a 20-pin SOIC (DW) package measuring 12.8 mm × 10.3 mm (body: 12.80 mm × 7.50 mm), RoHS-compliant with NIPDAU lead finish and MSL Level-1 reflow rating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ACT244DWR and SN74LVC240APWR, SN74ACT240DWR uniquely combines 5 V tolerance, inverting logic, and industrial temperature range in SOIC-20 - making it irreplaceable for legacy-aware bus isolation where polarity inversion and voltage robustness are jointly required.

Availability

SN74ACT240DWR is available at Aetrix Electronics and suitable for smartphone baseband interfaces, network switch backplane drivers, and industrial PLC I/O modules requiring stable component supply across extended production lifecycles.

Supply support for SN74ACT240DWR 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 interface ICs.

SN74ACT240DWR belongs to the ACT family of advanced CMOS logic devices engineered for high-speed, low-noise, 3-state bus interface applications in industrial, communications, and consumer electronics.

FAQ

What is the function of the 1OE and 2OE pins on the SN74ACT240DWR?

The 1OE and 2OE pins are active-low output-enable controls for the two independent 4-bit buffer sections. When 1OE is low, inputs 1A1–1A4 pass through as inverted outputs 1Y1–1Y4; when high, those outputs go high-impedance. The same applies to 2OE and the second section. This enables selective bus isolation without affecting the other channel, critical for multi-master arbitration in systems using SN74ACT240DWR.

Can SN74ACT240DWR interface directly with 3.3 V logic inputs?

Yes - SN74ACT240DWR inputs are TTL-compatible and accept voltages up to 5.5 V, so 3.3 V logic levels (VIH ≥ 2.0 V, VIL ≤ 0.8 V) meet its input threshold requirements at VCC = 4.5–5.5 V. However, its outputs swing rail-to-rail (0 V to VCC), so direct connection to 3.3 V–only receivers requires level translation unless the receiver is 5 V tolerant. SN74ACT240DWR itself does not perform level shifting.

What is the maximum continuous output current rating for SN74ACT240DWR?

SN74ACT240DWR is rated for ±24 mA per output under recommended operating conditions (VCC = 4.5–5.5 V, TA = –40 °C to +85 °C). Absolute maximum ratings permit ±50 mA short-term, but sustained operation above ±24 mA risks thermal overload or parametric shift. For SN74ACT240DWR, derating is required above 70 °C ambient per the device's RθJA = 101.2 °C/W (SOIC-20).

Does SN74ACT240DWR support hot insertion or live bus swapping?

No - SN74ACT240DWR lacks explicit hot-swap protection features such as power-up 3-state or bus-fault immunity. Its inputs and outputs are not designed to withstand voltage transients during live insertion. To implement hot-swap capability with SN74ACT240DWR, external circuitry (e.g., series resistors, TVS diodes, and controlled enable sequencing) must be added per system-level reliability requirements.

How does the propagation delay of SN74ACT240DWR compare across temperature and voltage?

SN74ACT240DWR's maximum propagation delay is specified as 8.5 ns at VCC = 5 V and TA = 25 °C. At minimum VCC = 4.5 V and maximum TA = 85 °C, tpd increases to ≤9.5 ns per datasheet Table 5.5. This variation is monotonic and predictable - designers using SN74ACT240DWR should apply the worst-case 9.5 ns value for timing closure in industrial temperature-grade applications.