Texas Instruments SN74HC157NG4

Overview

SN74HC157NG4 from Texas Instruments is a quadruple 2-line to 1-line data selector/multiplexer in a 16-pin PDIP package, operating from 2V to 6V supply, delivering 11ns typical propagation delay at 6V, ±6mA output drive at 5V, and 80µA max ICC - used for bus selection and data routing in digital logic systems.

For engineers reviewing the SN74HC157NG4 datasheet, SN74HC157NG4 pinout, SN74HC157NG4 application, or SN74HC157NG4 equivalent, this page provides verified functional mode behavior, real-world timing constraints (tpd ≤ 32ns at 6V/CL=50pF), TTL-compatible CMOS input thresholds, active-low strobe control, and validated alternative options for 2:1 multiplexing in industrial control and embedded interface designs.

Technical Context

The SN74HC157NG4 implements four independent 2:1 multiplexers sharing one address select (A/B) and one active-low strobe (G) input. All Y outputs reflect the selected A or B input when G is low; all outputs force low when G is high - enabling synchronous channel enable/disable across all four channels.

It uses high-speed silicon-gate CMOS technology with TTL-compatible input thresholds (VIH = 3.15V min at VCC = 4.5V, VIL = 1.35V max), standard CMOS input leakage (±1µA max), and rail-to-rail output swing (VOH ≥ 4.4V, VOL ≤ 0.26V at 4.5V/6mA). No internal latching or clocking - fully combinational operation.

Key Specifications

Pinout & Package

SN74HC157NG4 is supplied in a 16-pin plastic dual in-line package (PDIP-N), body size 19.31 mm × 6.35 mm, through-hole mountable, RoHS-compliant with NIPDAU lead finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC157NG4, SN74HC158N delivers inverted outputs requiring logic inversion in control firmware, while CD74HC157E offers extended temperature support but higher cost - SN74HC157NG4 remains optimal for standard commercial-grade 2:1 data routing where non-inverting behavior and cost efficiency are prioritized.

Availability

SN74HC157NG4 is available at Aetrix Electronics and suitable for industrial PLC I/O multiplexing, legacy bus interface selection, and digital logic prototyping requiring stable component supply, long-term manufacturability, and RoHS-compliant through-hole packaging.

Supply support for SN74HC157NG4 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 logic, power management, and signal chain solutions.

The SN74HC157NG4 belongs to TI's 74HC high-speed CMOS logic family, designed for low-power, pin-compatible upgrades to legacy TTL logic in industrial control, instrumentation, and interface applications.

FAQ

What is the function of the G pin on the SN74HC157NG4?

The G pin on the SN74HC157NG4 is the active-low strobe input. When G is high, all four Y outputs are forced low regardless of the A/B select or data inputs. When G is low, the multiplexers operate normally, routing either A or B to each Y output based on the A/B input state. This enables synchronized channel enable/disable in systems requiring glitch-free bus arbitration.

Does the SN74HC157NG4 support 3.3V operation?

Yes, the SN74HC157NG4 supports 3.3V operation within its specified 2V–6V supply range. At VCC = 3.3V, it maintains TTL-compatible input thresholds (VIH ≈ 2.3V min, VIL ≈ 0.99V max), delivers ~4mA output drive, and achieves ~18ns typical propagation delay (CL = 50pF). It is commonly used in mixed-voltage systems interfacing 3.3V controllers with 5V peripherals.

Can unused inputs on the SN74HC157NG4 be left floating?

No, unused inputs on the SN74HC157NG4 must not be left floating. As a CMOS device, floating inputs cause increased power consumption, potential oscillation, and reliability degradation. All unused inputs - including A/B, G, and any unconnected xA/xB - must be tied to VCC or GND via direct connection or a 10kΩ pull-up/down resistor, per TI's design guidelines in the SN74HC157NG4 datasheet.

What is the maximum capacitive load the SN74HC157NG4 can drive while meeting datasheet timing specs?

The SN74HC157NG4 is characterized for CL = 50pF in its switching characteristics table - all published tpd and tt values assume this load. While it can drive larger capacitances, performance degrades: at CL = 150pF, tpd increases to 49ns (max) at 6V. For guaranteed timing compliance, keep total output capacitance ≤ 50pF using short traces and minimal fanout; add buffering for heavier loads.

Is the SN74HC157NG4 pin-compatible with older 74LS157 devices?

No, the SN74HC157NG4 is not pin-compatible with the bipolar 74LS157. Although both are 16-pin DIP 2:1 multiplexers with identical pin numbering and basic function, the SN74HC157NG4 has different DC electrical characteristics (e.g., CMOS input structure, lower drive strength, no input bias current), and its G input is active-low while 74LS157 uses active-high enable. Direct replacement requires validation of logic thresholds and timing margins.