Texas Instruments 74ACT11157N

Overview

74ACT11157N from Texas Instruments is a 2-to-1 data selector/multiplexer with true-output logic, TTL-compatible inputs, and flow-through pin architecture for optimized PCB layout. It operates across −40°C to 85°C, delivers ±24 mA output drive at 5 V, and features center-pin V_CC/GND configuration to suppress high-speed switching noise in digital control systems.

For engineers reviewing the 74ACT11157N datasheet, 74ACT11157N pinout, 74ACT11157N application, or 74ACT11157N equivalent, key selection criteria include its dual-source 4-bit word routing capability, guaranteed 7.1 ns max t_PLH (A/B → Y), OE-controlled three-state outputs, and EPIC™ 1-µm CMOS process enabling latch-up immunity up to 500 mA at 125°C.

Technical Context

The 74ACT11157N implements a positive-logic 2:1 multiplexer with four independent channels, each selecting between corresponding bits of two 4-bit input buses (A and B) under control of a single A/B select line. All outputs are individually enabled via a common active-low OE input.

Its EPIC™ (Enhanced-Performance Implanted CMOS) process ensures rail-to-rail output swing, TTL-level input compatibility without external biasing, and robust noise margin-verified by 2.0 V V_IH min and 0.8 V V_IL max at V_CC = 4.5–5.5 V. The flow-through pinout places inputs and outputs on opposite sides of the 20-pin DIP package to minimize trace crossovers.

Key Specifications

Pinout & Package

74ACT11157N is supplied in a 20-pin plastic dual-inline package (PDIP), 300-mil width, with center-aligned V_CC (pin 10) and GND (pins 4, 5, 6, 7) to reduce simultaneous switching noise.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar data selector applications.

Compared with 74ACT157N and SN74LVC157APWR, the 74ACT11157N uniquely provides synchronized 4-bit selection via one A/B line and native 5-V operation with industrial temperature support-making it optimal for retrofitting or maintaining legacy 5-V digital control systems requiring deterministic bus routing.

Availability

74ACT11157N is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, digital test equipment data routing, and legacy bus interface adapter applications requiring stable component supply and long-term obsolescence management.

Supply support for 74ACT11157N 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 founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The 74ACT11157N belongs to TI's Advanced CMOS (ACT) logic family, engineered for high-speed, low-noise 5-V digital systems where TTL compatibility, latch-up immunity, and PCB layout efficiency are critical design requirements.

FAQ

What is the function of the A/B pin on the 74ACT11157N?

The A/B pin on the 74ACT11157N is a global bus select control that determines which of the two 4-bit input sources (A or B) is routed to the four true outputs (1Y–4Y). When A/B is low, the A bus (1A–4A) is selected; when high, the B bus (1B–4B) is selected. This enables atomic, synchronized switching of an entire 4-bit word without per-bit control logic, a key feature distinguishing the 74ACT11157N from variants like the 74ACT157N.

Does the 74ACT11157N support 3.3-V operation?

No, the 74ACT11157N is specified only for 4.5 V to 5.5 V supply operation and is not rated for reliable 3.3-V use. Its input thresholds (V_IL = 0.8 V, V_IH = 2.0 V) and output drive characteristics are optimized for 5-V TTL/CMOS systems. Attempting 3.3-V operation may result in marginal noise margins or undefined switching behavior. For 3.3-V designs, consider TI's SN74LVC157A or similar LVC-family devices instead of the 74ACT11157N.

How does the 74ACT11157N differ from the 74ACT157N?

The 74ACT11157N integrates a single A/B select line controlling all four multiplexer channels simultaneously, whereas the 74ACT157N uses two independent select inputs (S0, S1) controlling two pairs of channels. The 74ACT11157N also features a distinct flow-through pinout and center-pin V_CC/GND arrangement for noise reduction-unlike the 74ACT157N's conventional layout. These differences make the 74ACT11157N better suited for applications requiring atomic 4-bit bus selection and improved high-speed layout integrity.

What is the maximum output current rating for the 74ACT11157N?

The 74ACT11157N is rated for ±24 mA DC output current per channel under recommended operating conditions (V_CC = 4.5–5.5 V, T_A = −40°C to 85°C). This is verified by VOL ≤ 0.44 V at I_OL = 24 mA and VOH ≥ 3.94 V at I_OH = −24 mA. Exceeding this rating risks violating output voltage specifications or accelerating device wear; the absolute maximum rating of ±50 mA applies only for short-duration pulse testing, not continuous operation.

Is the 74ACT11157N pin-compatible with any surface-mount alternatives?

No direct surface-mount pin-compatible replacement exists for the 74ACT11157N in TI's portfolio. Its 20-pin PDIP footprint and unique pin assignment-including four GND pins (4–7), center V_CC (pin 10), and distributed I/O-do not map to standard SOIC or TSSOP packages. Engineers migrating to surface-mount must redesign the layout and evaluate functional equivalents such as the SN74ACT157D (SOIC-16), accepting trade-offs in select logic granularity and noise suppression architecture versus the original 74ACT11157N.