Texas Instruments 74AC11257PWR

Overview

74AC11257PWR from Texas Instruments is a quadruple 2-line-to-1-line data selector/multiplexer with 3-state outputs in a 20-pin TSSOP package. It supports 3 V to 5.5 V supply operation, delivers ±24 mA output drive at 5.5 V, and features propagation delays as low as 3.6 ns (tPLH) at VCC = 5 V. It enables bus interface from four independent 2-bit data sources in high-performance digital systems such as industrial controllers and communication backplanes.

For engineers reviewing the 74AC11257PWR datasheet, 74AC11257PWR pinout, 74AC11257PWR application, or 74AC11257PWR equivalent, key selection criteria include 3-state bus compatibility, flow-through pin architecture for PCB layout optimization, latch-up immunity of 500 mA at 125°C, and guaranteed operation across −40°C to 85°C.

Technical Context

This device implements four independent 2:1 multiplexers, each selecting between two inputs (A/B) based on a shared select line (A/B), with individual 3-state enable control per output via OE. All outputs share a common output-enable input, not per-channel control.

Its AC logic family ensures CMOS-level noise immunity and rail-to-rail output swing, with input thresholds defined at 30% and 70% of VCC. The center-pin VCC/GND configuration reduces high-speed switching noise, and absolute maximum ratings support up to 7 V supply without damage.

Key Specifications

Pinout & Package

TSSOP-20 (PW) package: 4.4 mm × 6.5 mm body, 0.65 mm lead pitch, 1.2 mm max height, RoHS-compliant NiPdAu finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 4-channel 2:1 multiplexer applications.

Compared with 74AC11257PWR, SN74LV4052APWR trades digital bus compatibility for analog flexibility, while 74LVC157APW sacrifices noise suppression and latch-up robustness for lower static power - making 74AC11257PWR the preferred choice for industrial bus interface where signal integrity and ruggedness are critical.

Availability

74AC11257PWR is available at Aetrix Electronics and suitable for industrial PLC backplanes, automotive diagnostic interfaces, and communications baseband processing requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant sourcing.

Supply support for 74AC11257PWR 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 heritage in high-reliability logic families.

The 74AC logic series was engineered for high-speed, low-noise digital interfacing in industrial and telecom infrastructure, emphasizing latch-up immunity, wide voltage operation, and PCB-layout-friendly packaging.

FAQ

What is the recommended power-up sequence for 74AC11257PWR to ensure high-impedance outputs at startup?

TI recommends tying OE to VCC through a pullup resistor during power-up to guarantee all outputs remain in high-impedance state until system initialization completes. The minimum resistor value depends on the current-sinking capability of the OE driver; for standard microcontroller GPIO, a 10 kΩ pullup is sufficient. This prevents bus contention before firmware configures the select and enable lines. The 74AC11257PWR itself has no internal power-on reset circuitry, so external OE control is mandatory for safe startup behavior.

Can 74AC11257PWR operate reliably at 3.3 V while interfacing with 5 V logic devices?

Yes, 74AC11257PWR operates across 3 V to 5.5 V and maintains full logic-level compatibility: its VIH threshold is 2.1 V at VCC = 3 V, ensuring recognition of 3.3 V or 5 V high signals, and its VOL remains ≤0.44 V at IOL = 12 mA. However, direct connection to 5 V outputs requires current-limiting resistors or level-shifting if those outputs exceed 5.5 V absolute max - the 74AC11257PWR input clamp current is ±20 mA, so sustained overvoltage must be avoided. The 74AC11257PWR is designed for mixed-voltage system integration without external translators in most cases.

Does 74AC11257PWR support independent enable control for each of the four multiplexer outputs?

No, 74AC11257PWR provides a single shared output-enable (OE) input that simultaneously controls all four Y outputs. When OE is high, all outputs go high-impedance; when OE is low, all outputs become active and reflect their respective A/B selections. There is no per-channel enable functionality. This architecture simplifies control logic but requires external gating (e.g., using AND gates or MCU GPIO) if independent output disabling is needed. The 74AC11257PWR datasheet confirms this in the FUNCTION TABLE and logic diagram - OE is a global signal, not replicated per channel.

What is the thermal performance of 74AC11257PWR in continuous operation at 85°C ambient?

The 74AC11257PWR in TSSOP (PW) package has a junction-to-ambient thermal resistance (θJA) of 83°C/W. At 85°C ambient and typical ICC of 80 µA (quiescent) plus dynamic power dissipation, junction temperature remains well below the 125°C limit - even under worst-case switching conditions with 50 pF loads at 10 MHz, calculated power stays below 150 mW, resulting in ~110°C junction temp. TI specifies 500 mA latch-up immunity at 125°C, confirming robustness beyond normal operating limits. Derating is not required for 74AC11257PWR in standard industrial airflow environments.

How does the flow-through pin architecture of 74AC11257PWR improve PCB layout compared to conventional logic packages?

The flow-through pinout - with inputs on the left (pins 1–4, 5–8), select/enable on top/middle (pins 9, 12), and outputs on the right (pins 10, 11, 13, 14) - allows straight-layer signal routing from connector → 74AC11257PWR → FPGA/microcontroller without vias or layer changes. This reduces parasitic inductance, minimizes crosstalk, and cuts layout time by up to 40% versus zig-zag pinouts. TI's SCAS049C datasheet explicitly cites "optimizes PCB layout" as a key benefit, and the physical pin map confirms left-to-right signal flow matches standard bus organization - a tangible advantage for high-density industrial control boards where 74AC11257PWR is commonly deployed.