Texas Instruments 74ACT11240DBR

Overview

74ACT11240DBR from Texas Instruments is an octal inverting buffer/line driver with 3-state outputs, designed for memory address and bus driving in high-density digital systems. It operates from −40°C to 85°C at 4.5–5.5 V, delivers ±24 mA output drive, features TTL-compatible inputs, and uses EPIC CMOS process for latch-up immunity up to 500 mA at 125°C.

For engineers reviewing the 74ACT11240DBR datasheet, 74ACT11240DBR pinout, 74ACT11240DBR application, or 74ACT11240DBR equivalent, key selection criteria include 3-state control timing (tPZH ≤ 10 ns), symmetrical active-low OE inputs, flow-through pinout for PCB layout optimization, and compatibility with 5-V TTL logic families in bus-hold and clock distribution roles.

Technical Context

This device integrates two independent 4-bit inverting buffers, each with dedicated active-low output-enable (OE) control. All eight outputs enter high-impedance state when their respective OE is high, enabling bidirectional bus sharing without external direction control logic.

It employs EPIC (Enhanced-Performance Implanted CMOS) 1-μm process technology, delivering rail-to-rail output swing, low input capacitance (4 pF), and reduced switching noise via center-pin VCC/GND configuration. The flow-through architecture places inputs on one side and outputs on the opposite side of the 24-pin SSOP package.

Key Specifications

Pinout & Package

74ACT11240DBR is housed in a 24-pin Shrink Small-Outline Package (SSOP, DB), measuring 8.2 mm × 3.9 mm with 0.65 mm lead pitch. The package features center-aligned VCC (pins 14, 15) and GND (pins 7, 8, 9, 10) to minimize ground bounce and supply noise during high-speed switching.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ACT240DBR and 74ACT11244DBR, the 74ACT11240DBR offers fixed inverting behavior optimized for address decoding and memory enable logic, whereas alternatives add functional flexibility at the cost of increased design complexity or polarity constraints in fixed-logic systems.

Availability

74ACT11240DBR is available at Aetrix Electronics and suitable for industrial control systems, legacy bus interface modules, and memory subsystem designs requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for 74ACT11240DBR 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 decades of experience in high-reliability industrial and automotive ICs.

The 74ACT11240DBR belongs to TI's advanced CMOS logic family, engineered for high-speed, low-noise bus interfacing in industrial computing and real-time control systems where signal integrity and thermal robustness are critical.

FAQ

What is the maximum operating frequency supported by the 74ACT11240DBR?

The 74ACT11240DBR does not specify a hard maximum clock frequency, but its propagation delay (tPLH/tPHL ≤ 10.6 ns at 25°C) and 3-state timing (tPZH ≤ 10 ns) support reliable operation in bus systems running up to 80 MHz. Real-world frequency limits depend on load capacitance, trace length, and termination; for 50-pF loads, it sustains clean edges beyond 100 MHz in controlled impedance environments. The 74ACT11240DBR is typically deployed in address/data buses rather than continuous clock distribution.

Does the 74ACT11240DBR require external pull-up or pull-down resistors on its inputs?

No, the 74ACT11240DBR has TTL-compatible input thresholds (VIH = 2 V, VIL = 0.8 V) and internal input structure that does not require external biasing. Its inputs are designed to interface directly with standard 5-V TTL or CMOS outputs. Unused inputs should be tied to VCC or GND to prevent floating nodes and unintended switching; however, no pull-up/pull-down resistors are needed for functional operation. This applies equally to all control and data inputs of the 74ACT11240DBR.

Can the 74ACT11240DBR drive standard 50-Ω transmission lines directly?

The 74ACT11240DBR is not designed for direct 50-Ω line driving: its ±24 mA output drive is optimized for capacitive bus loading (e.g., 50 pF), not resistive termination. Driving a 50-Ω line would draw ~100 mA at 5 V, exceeding its absolute maximum output current rating (±50 mA). For transmission line applications, use the 74ACT11240DBR to drive a series-terminated source or pair it with a dedicated line driver IC. This limitation applies consistently across all output pins of the 74ACT11240DBR.

What is the meaning of "flow-through architecture" in the context of the 74ACT11240DBR?

Flow-through architecture refers to the physical pin arrangement of the 74ACT11240DBR: inputs are located on the left side (pins 1–4, 13, 17–20) and corresponding outputs on the right side (pins 11–12, 21–24), enabling straight-line PCB routing without vias or layer jumps. This minimizes trace length, reduces crosstalk, and improves signal integrity in high-density layouts. The term specifically describes the mechanical layout of the 74ACT11240DBR package-not a functional or architectural feature-and is confirmed by its top-view pin diagram.

Is the 74ACT11240DBR pin-compatible with older 74LS or 74F series octal buffers?

No, the 74ACT11240DBR is not pin-compatible with 74LS or 74F series devices such as the 74LS240 or 74F240. While functionally similar, it uses a different 24-pin SSOP (DB) footprint with distinct pin assignments-including dual VCC (pins 14/15) and quad GND (pins 7–10)-and lacks the DIP or SOIC pinouts of legacy families. Direct replacement requires PCB redesign. This applies strictly to the 74ACT11240DBR variant and does not extend to other packages like DW or NT.