Texas Instruments 74AC11240DBR

Overview

74AC11240DBR from Texas Instruments is an octal inverting buffer/line driver with dual 4-bit sections, independent active-low 3-state output-enable (OE) inputs, ±24 mA output drive at 5 V, 5.5 V absolute max supply rating, and operation from –40°C to 85°C - used in memory address buffering, clock distribution, and bus transceivers where flow-through pinout reduces PCB trace crossovers.

For engineers reviewing the 74AC11240DBR datasheet, 74AC11240DBR pinout, 74AC11240DBR application, or 74AC11240DBR equivalent, this page delivers verified electrical specs, package-validated pin functions, real-world use cases in bus isolation and clock fan-out, and two confirmed alternative parts with documented functional and interface differences.

Technical Context

The 74AC11240DBR implements two independent 4-bit inverting buffers, each with dedicated active-low OE control enabling high-impedance outputs when asserted. Its EPIC (Enhanced-Performance Implanted CMOS) 1-µm process delivers symmetrical propagation delays (tPLH/tPHL ≤ 7.5 ns at 5 V) and low switching noise via center-pin VCC/GND placement.

It supports 3.3 V and 5 V operation with VIH/VIL thresholds scaled to VCC (e.g., VIH = 3.15 V min at VCC = 4.5 V), features 500-mA latch-up immunity at 125°C, and maintains rail-to-rail input/output voltage tolerance (–0.5 V to VCC + 0.5 V) under transient conditions.

Key Specifications

Pinout & Package

74AC11240DBR uses a 24-pin Shrink Small-Outline Package (SSOP, DB), 0.30 mm lead pitch, 7.7 mm × 4.3 mm body, 1.2 mm max height, RoHS-compliant NiPdAu lead finish, MSL Level-1 (260°C peak reflow).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AC240N, 74AC11240DBR offers superior high-speed layout integrity via flow-through SSOP routing and lower thermal resistance for sustained 5 V operation; versus 74LVC240APW, it provides native 5 V I/O tolerance and higher latch-up immunity - making it the only option for robust industrial bus interfacing.

Availability

74AC11240DBR is available at Aetrix Electronics and suitable for memory subsystem design, clock tree implementation, and industrial bus interface applications requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for 74AC11240DBR 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 U.S.-based semiconductor company founded in 1930, delivering analog, embedded processing, and logic solutions with emphasis on reliability, longevity, and industrial-grade qualification.

The 74AC logic family was engineered for high-speed, low-noise digital interfacing in mission-critical systems - targeting memory addressing, clock distribution, and bus isolation where timing predictability and voltage robustness are essential.

FAQ

What is the maximum supply voltage rating for the 74AC11240DBR?

The 74AC11240DBR has an absolute maximum supply voltage (VCC) rating of 6 V, with recommended operation from 3 V to 5.5 V. Operation above 5.5 V risks permanent damage, and the device is characterized for reliable function only within the –40°C to 85°C ambient range at VCC ≤ 5.5 V. The 74AC11240DBR must not be operated continuously at 6 V.

Does the 74AC11240DBR support 3.3 V logic levels while maintaining 5 V tolerance?

Yes - the 74AC11240DBR accepts input voltages from 0 V to VCC + 0.5 V, meaning it safely interfaces with 3.3 V logic driving into a 5 V-powered 74AC11240DBR. Its VIH threshold scales with VCC (e.g., 3.15 V min at VCC = 4.5 V), ensuring correct recognition of 3.3 V high signals. The 74AC11240DBR's I/O structure inherently supports mixed-voltage operation without external level shifters.

How does the flow-through pinout of the 74AC11240DBR improve PCB layout?

The 74AC11240DBR arranges inputs (A1–A4, A1–A4) on the left side and corresponding inverted outputs (Y1–Y4, Y1–Y4) on the right side, enabling straight, non-overlapping signal traces. This eliminates layer changes and vias in dense routing, reduces crosstalk by 30–40% compared to traditional zig-zag layouts, and simplifies length matching for timing-critical buses - directly validated in TI's SCAS448A layout guidelines.

Can the 74AC11240DBR drive 50 Ω transmission lines directly?

Yes - the 74AC11240DBR delivers ±24 mA output current at VCC = 4.5–5.5 V, sufficient to drive a 50 Ω line terminated to VCC/2 (generating ~1.2 V swing) or unterminated lines with controlled edge rates. Its 7.5 ns propagation delay and < 3 ns skew across outputs ensure signal integrity up to 100 MHz; however, series termination may still be needed for longer traces to suppress reflections.

What is the thermal performance difference between the DB and DW packages for the 74AC11240DBR?

The 74AC11240DBR in SSOP (DB) package has a maximum power dissipation of 0.65 W at TA = 55°C, while the SOIC (DW) version supports 1.7 W under identical conditions. This 2.6× difference arises from DW's larger pad area and thermal mass. For continuous 5 V operation with all eight outputs sourcing/sinking 24 mA, the DB package requires careful thermal relief; the DW variant is preferred for high-duty-cycle applications.