Texas Instruments SN74HC157N

Overview

SN74HC157N 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 5V, ±6mA output drive, and 80µA max ICC. It routes four independent 2:1 data paths under shared A/B address and active-low strobe (G) control, used in bus selection and signal routing within digital logic subsystems.

For engineers reviewing the SN74HC157N datasheet, SN74HC157N pinout, SN74HC157N application, or SN74HC157N equivalent, this page delivers verified functional identity, validated PDIP-16 pin mapping, confirmed CMOS-compatible switching specs, and real-world multiplexer use cases - all grounded in TI's SCLS113F production datasheet.

Technical Context

The SN74HC157N implements four independent 2:1 multiplexers with synchronous address control (A/B) and a global active-low enable (G). All outputs go low when G is high, regardless of A/B or input states - enabling clean bus isolation. Its CMOS inputs meet TTL voltage thresholds and require termination to VCC or GND to prevent floating-induced oscillation.

It operates asynchronously with no internal clock; each Y output directly reflects the selected A or B input per the function table. Propagation delay varies with supply voltage (11ns typ at 5V, 32ns max at 6V, CL = 50pF), and output transition time is as fast as 6ns (typ, 6V).

Key Specifications

Pinout & Package

SN74HC157N uses a 16-pin plastic dual in-line package (PDIP), body size 19.31 mm × 6.35 mm, through-hole mountable with 0.1-inch lead spacing. Pin numbering follows standard DIP orientation (pin 1 in top-left corner, notch or dot marking pin 1 end).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC157N, SN74HCT157N improves TTL input compatibility at the cost of higher quiescent current, while CD74HC157E provides identical functionality under a different TI product prefix - both preserve the same PDIP-16 layout and multiplexer timing behavior.

Availability

SN74HC157N is available at Aetrix Electronics and suitable for microcontroller bus expansion, digital test equipment signal routing, industrial PLC I/O multiplexing, and legacy system interface adapter designs requiring stable component supply and long-term obsolescence resilience.

Supply support for SN74HC157N 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 SN74HC157N belongs to TI's 74HC high-speed CMOS logic series, designed for low-power, wide-voltage digital signal routing in industrial, computing, and communications equipment where pin-compatible upgrades and robust noise immunity are essential.

FAQ

What is the function of the G (strobe) pin on the SN74HC157N?

The G pin on the SN74HC157N is an active-low output strobe. When G is HIGH, all four Y outputs are forced LOW regardless of the A/B address or input states - providing hardware-level bus isolation. When G is LOW, the multiplexer operates normally, routing selected A or B inputs to their respective Y outputs. This behavior is explicitly defined in the Function Table of TI's SCLS113F datasheet and applies identically to the SN74HC157N.

Can SN74HC157N operate reliably at 3.3V supply voltage?

Yes, SN74HC157N operates reliably across 2V to 6V, including 3.3V. At VCC = 3.3V, its typical propagation delay is ~18ns (CL = 50pF), VOH ≥ 3.15V (IOH = −20µA), and VOL ≤ 0.1V (IOL = 20µA), meeting standard 3.3V logic thresholds. These values are specified in Section 4.2 and 4.4 of the official TI datasheet for SN74HC157N and confirmed across temperature and process corners.

Is SN74HC157N pin-compatible with older 74LS157 devices?

No, SN74HC157N is not pin-compatible with 74LS157. While both are quadruple 2:1 multiplexers in 16-pin PDIP packages and share identical pin functions (A/B, G, 1A–4B, 1Y–4Y, VCC, GND), the 74LS157 uses different internal logic design and has distinct DC/AC characteristics. However, SN74HC157N can serve as a functional replacement in many designs due to matching pinout and TTL-compatible inputs - but timing and drive strength differences must be verified per application.

What is the maximum capacitive load SN74HC157N can drive while maintaining datasheet timing specs?

SN74HC157N is characterized for CL = 50pF in its switching specifications - all tpd and tt values in Section 4.5 assume this load. Driving larger capacitances (e.g., >100pF) increases propagation delay and transition time beyond guaranteed limits; for example, tpd rises to 49ns max at 6V with CL = 150pF. To maintain datasheet timing, keep total output capacitance ≤50pF via short traces and minimal fanout - as recommended in TI's Application and Implementation section for SN74HC157N.

Does SN74HC157N require external pull-up or pull-down resistors on unused inputs?

Yes, all unused inputs on SN74HC157N must be terminated to either VCC or GND - floating CMOS inputs cause excessive power consumption and potential oscillation. A 10kΩ resistor is recommended for pull-up/pull-down if the input is intermittently driven; direct connection is acceptable for permanently unused inputs. This requirement is explicitly stated in TI's SCLS113F datasheet Section 6.3.1 and applies to every input pin (A/B, G, 1A–4B) of the SN74HC157N.