Texas Instruments CD74AC157E-NG

Overview

CD74AC157E-NG from Texas Instruments is a quadruple 2-line to 1-line data selector/multiplexer in 16-pin PDIP package, operating from 1.5V to 5.5V supply, delivering balanced propagation delay, ±24mA output drive, and true-data routing for 4-bit parallel bus selection in digital control systems.

For engineers reviewing the CD74AC157E-NG datasheet, CD74AC157E-NG pinout, CD74AC157E-NG application, or CD74AC157E-NG equivalent, key selection criteria include VCC range compatibility (1.5–5.5V), active-low strobe (G) behavior, 4-channel independent 2:1 multiplexing, output drive strength (±24mA at 4.5–5.5V), and thermal performance in industrial temperature range (–55°C to 125°C).

Technical Context

The CD74AC157E-NG implements four independent CMOS 2:1 multiplexers sharing one address select (A/B) and one active-low strobe (G). When G is high, all Y outputs are forced low regardless of A/B or input states; when G is low, each Yx selects either Ax or Bx based on A/B logic level.

It uses silicon-gate CMOS technology with balanced push-pull outputs, standard CMOS inputs, and internal clamp diodes. Propagation delays are tightly matched across channels - e.g., tPLH/tPHL = 2.1–8.5 ns at VCC = 5V, CL = 50pF - enabling synchronous 4-bit data routing without skew-induced timing violations.

Key Specifications

Pinout & Package

CD74AC157E-NG is housed in a 16-pin plastic dual in-line package (PDIP-N), body size 19.3 mm × 6.35 mm, with through-hole mounting and industry-standard 0.3-inch row spacing.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AC157N, CD74AC157E-NG offers identical functionality and drop-in compatibility; versus 74LCX157M, it provides broader voltage flexibility and guaranteed 5V operation - critical for industrial retrofits and multi-rail systems where supply voltage headroom is constrained.

Availability

CD74AC157E-NG is available at Aetrix Electronics and suitable for industrial PLCs, automotive diagnostics modules, automated test equipment, and mixed-voltage embedded gateways requiring stable component supply across extended temperature ranges.

Supply support for CD74AC157E-NG 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 over 50 years of innovation in high-reliability logic families.

The CD74AC157E-NG belongs to TI's AC-series advanced CMOS logic product line, engineered for low-power, high-speed data routing in harsh-environment applications including factory automation and transportation systems.

FAQ

What is the maximum clock/data rate supported by CD74AC157E-NG?

The CD74AC157E-NG does not operate on a clock; it is asynchronous. Its maximum usable data rate depends on propagation delay and load. At VCC = 5V and CL = 50pF, tPLH/tPHL is 2.1–8.5 ns, supporting clean 4-bit data switching up to ~100 MHz in well-terminated layouts. For reliable operation, maintain input transition rates ≤20 ns/V (per Recommended Operating Conditions) to prevent oscillation.

Does CD74AC157E-NG support 5V-tolerant inputs when operated at 3.3V VCC?

No. CD74AC157E-NG is not 5V-tolerant. When VCC = 3.3V, absolute maximum input voltage is 6V, but VIH(min) = 2.1V and VIL(max) = 0.9V - applying 5V signals risks latch-up or damage. For 5V-to-3.3V interfacing, use external resistive dividers or dedicated level translators; the device itself does not provide voltage translation.

Can unused inputs on CD74AC157E-NG be left floating?

No. All CMOS inputs on CD74AC157E-NG - including A/B, G, and any unconnected A/B data lines - must be terminated to VCC or GND. Floating inputs cause excessive current draw, logic instability, and potential device damage due to partial conduction in input transistors. Use 10kΩ pull-up or pull-down resistors where dynamic control is needed.

What is the purpose of the thermal pad in CD74AC157E-NG packages?

CD74AC157E-NG is supplied in PDIP (N) package, which has no thermal pad. The thermal pad reference applies only to the WQFN (BQB) variant (e.g., CD74AC157BQBR). For CD74AC157E-NG, thermal management relies on PCB copper area connected to pins 8 (GND) and 16 (VCC); no thermal pad exists or requires connection.

How does the strobe (G) pin affect output behavior when transitioning between states?

When G transitions from low to high, all four Y outputs go low within tPHL(G→Y) ≤ 13.5 ns (VCC = 5V). When G transitions from high to low, outputs resume normal multiplexing after tPLH(G→Y) ≤ 13.5 ns - but only if A/B and data inputs are stable. Glitch-free operation requires A/B to be held steady during G transitions; violating setup/hold times may cause transient invalid outputs.