Texas Instruments CD74AC151E

Overview

CD74AC151E from Texas Instruments is a high-speed CMOS 8-line to 1-line data selector/multiplexer with balanced push-pull outputs, ±24mA drive capability at 4.5–5.5V, 1.5–5.5V supply operation, and dual complementary outputs (Y and inverted W). It performs Boolean function generation and parallel-to-serial conversion in digital control logic, industrial PLC I/O modules, and test equipment signal routing.

For engineers reviewing the CD74AC151E datasheet, CD74AC151E pinout, CD74AC151E application, or CD74AC151E equivalent, key selection considerations include its 3.4ns minimum propagation delay (VCC = 5V), strobe-controlled enable/disable behavior, dual-output architecture, and compatibility with 1.5V–5.5V mixed-voltage systems requiring low-power, noise-immune multiplexing.

Technical Context

The CD74AC151E implements an asynchronous 8:1 multiplexer using silicon-gate CMOS technology, where address inputs A, B, C select one of eight data inputs (D0–D7) to pass to the Y output; W is its logical inverse. The active-low strobe (G) overrides selection and forces Y = L, W = H regardless of address or data states.

Its balanced CMOS push-pull outputs support ±24mA sourcing/sinking at 4.5–5.5V, enabling direct fanout to 15 F-series devices. Input transition rate limits (20–50 ns/V) and strict VIH/VIL thresholds ensure reliable operation across –40°C to +85°C ambient, with SCR-latchup-resistant process design for robustness in noisy industrial environments.

Key Specifications

Pinout & Package

CD74AC151E is supplied in a 16-pin PDIP (Plastic Dual In-line Package) with 0.300-inch body width and through-hole mounting. Pin 1 is D3; pin 16 is VCC. Thermal pad not present.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8:1 multiplexer applications.

Compared with SN74AC151N, CD74AC151E offers identical performance but reflects TI's legacy part numbering; versus 74HC151N, CD74AC151E delivers 2.5× faster switching, 6× higher drive strength, and guaranteed latchup immunity - essential for demanding industrial signal routing.

Availability

CD74AC151E is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, test equipment signal routing, digital logic function generation, and parallel-to-serial data conversion requiring stable component supply and long-term manufacturability.

Supply support for CD74AC151E 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 company specializing in analog and embedded processing technologies, with leadership in precision analog, power management, and logic ICs for industrial, automotive, and communications markets.

The CD74AC151E belongs to TI's advanced CMOS (AC) logic family, designed specifically for high-speed, low-power digital signal routing in noise-prone industrial and instrumentation applications where voltage flexibility and robustness are critical.

FAQ

What is the minimum supply voltage required for CD74AC151E to operate correctly?

The CD74AC151E operates down to 1.5V, as specified in the Recommended Operating Conditions. At this voltage, it maintains full functionality including proper logic threshold margins (VIH = 1.2V, VIL = 0.3V) and guaranteed propagation delay (169ns max). This enables use in battery-backed or energy-harvesting systems where supply headroom is constrained. The CD74AC151E retains noise immunity at 30% of VCC even at 1.5V operation.

Does CD74AC151E support hot insertion or live swapping in powered-backplane systems?

No, CD74AC151E does not support hot insertion. Its Absolute Maximum Ratings specify that VCC must be applied before any input signal, and inputs must remain within 0 to VCC during power-up/down. Violating this sequence risks latchup or ESD damage. For hot-swap applications, external protection circuitry (e.g., series resistors, clamping diodes) and controlled power sequencing are required. The CD74AC151E itself lacks internal hot-swap features like power-on reset or input current limiting.

Can CD74AC151E drive a 50Ω transmission line directly?

No, CD74AC151E cannot drive a 50Ω transmission line directly. Its ±24mA output drive at 4.5–5.5V yields a minimum effective output impedance of ~188Ω (5V/24mA), far higher than 50Ω. Attempting direct 50Ω termination causes severe signal degradation and violates VOL/VOH specs. For transmission line driving, use a dedicated line driver (e.g., SN65LVDS1) or add series termination. The CD74AC151E is rated for ≤50pF capacitive loads - not resistive line matching.

How does the strobe (G) input affect the W output in CD74AC151E?

When the strobe (G) input is high, the CD74AC151E forces W to a logic HIGH state regardless of address (A/B/C) or data (D0–D7) inputs. When G is low, W becomes the logical inverse of the selected Y output. This behavior is explicitly defined in the Function Table and Logic Diagram. The CD74AC151E guarantees W = H and Y = L simultaneously during strobe assertion - a key feature for bus contention avoidance and synchronous blanking in time-critical systems.

Is CD74AC151E pin-compatible with older CD74HC151 devices?

No, CD74AC151E is not pin-compatible with CD74HC151. Although both are 16-pin PDIP 8:1 multiplexers with identical pin numbering (D3, D2, D1, D0, Y, W, G, GND, C, B, A, D7, D6, D5, D4, VCC), their electrical characteristics differ significantly: CD74AC151E has ±24mA drive and 1.5–5.5V operation, while CD74HC151 is limited to ±4mA and 2–6V. Swapping them may cause overcurrent, incorrect logic thresholds, or failure to operate below 2V. The CD74AC151E requires verification of supply and load conditions before substitution.