Texas Instruments SN74HC157D

Overview

SN74HC157D from Texas Instruments is a quadruple 2-line to 1-line data selector/multiplexer in SOIC-16 package, operating from 2 V to 6 V supply, delivering 11 ns typical propagation delay at 5 V, ±6 mA output drive, and 80 µA max ICC - used for bus switching and signal routing in digital logic systems.

For engineers reviewing the SN74HC157D datasheet, SN74HC157D pinout, SN74HC157D application, or SN74HC157D equivalent, this page provides verified functional identity, validated SOIC-16 pin mapping, confirmed 4-channel 2:1 multiplexing behavior, real-world timing and drive capability data, and two technically documented alternative parts with precise functional and application distinctions.

Technical Context

The SN74HC157D implements four independent 2:1 multiplexers sharing one address select (A/B) input and one active-low strobe (G) input; all outputs are forced low when G is high. It operates asynchronously with no internal clock or state retention.

Each channel selects between two CMOS/TTL-compatible inputs (A and B) based on A/B logic level, with output Y = A when A/B = L and Y = B when A/B = H - all under control of the same A/B and G signals across all four channels.

Key Specifications

Pinout & Package

SN74HC157D is housed in a 16-pin SOIC (Small Outline Integrated Circuit) package measuring 9.90 mm × 3.90 mm, with standard 1.27 mm pitch and gull-wing leads suitable for surface-mount reflow assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC157D, SN74HC158D adds functional inversion at identical speed and drive, while 74LVC157D trades supply flexibility for higher speed in 3.3 V systems - neither is pin-compatible replacement, but both serve distinct design constraints in multiplexer-based data routing.

Availability

SN74HC157D is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, digital test equipment signal routing, microcontroller peripheral bus sharing, and legacy system data path arbitration requiring stable component supply and long-term sourcing continuity.

Supply support for SN74HC157D 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 U.S.-based semiconductor company specializing in analog and embedded processing technologies, with leadership in logic, power management, and signal chain solutions.

The SN74HC157D belongs to TI's industry-standard 74HC logic family, designed for high-speed, low-power digital signal routing in industrial control, instrumentation, and legacy system upgrades.

FAQ

What is the function of the G (strobe) pin on the SN74HC157D?

The G pin on the SN74HC157D is an active-low global strobe that forces all four Y outputs low regardless of the states of A/B or data inputs. This enables synchronized channel blanking during bus handoffs or fault conditions. When G is high, outputs remain low even if A/B and inputs are valid - making it essential for glitch-free arbitration in time-critical digital systems using SN74HC157D.

Can SN74HC157D operate reliably at 3.3 V supply voltage?

Yes, SN74HC157D operates reliably across 2 V to 6 V, including 3.3 V. At VCC = 3.3 V, its VIH(min) is 2.31 V and VIL(max) is 1.0 V per TI's Recommended Operating Conditions, ensuring compatibility with standard 3.3 V CMOS outputs. Propagation delay increases to ~19 ns (typical), and output drive drops to ±4.2 mA - still sufficient for driving 74HC/74AHC loads without buffering in SN74HC157D-based designs.

Is SN74HC157D pin-compatible with SN74LS157N?

No, SN74HC157D is not pin-compatible with SN74LS157N. While both are quad 2:1 multiplexers with identical logic function and 16-pin DIP/SOIC footprints, SN74LS157N uses a different pinout: its G (strobe) is on pin 5, whereas SN74HC157D places G on pin 15. Interchanging them without PCB revision will cause functional failure. Always verify pin mapping before substitution - SN74HC157D must be used with its defined SOIC-16 layout.

What is the maximum capacitive load SN74HC157D can drive while meeting datasheet timing specs?

SN74HC157D is characterized for CL = 50 pF in its Switching Characteristics table, where tpd = 11 ns (typical) and tt = 6 ns (typical) at VCC = 5 V. Driving >50 pF increases propagation delay nonlinearly - e.g., at CL = 150 pF, tpd rises to 32 ns (max). For guaranteed timing compliance in SN74HC157D applications, keep total load capacitance ≤50 pF via short traces and minimal fanout; larger loads require buffer isolation.

Does SN74HC157D support hot insertion or live swapping in backplane systems?

No, SN74HC157D does not support hot insertion. Its Absolute Maximum Ratings specify no protection against supply sequencing violations or I/O pin biasing during power-up/down. Applying VCC after signal inputs may forward-bias input clamps, risking latch-up or parametric shift. For backplane applications requiring live swap, use hot-swap controllers or buffers upstream of SN74HC157D - never insert SN74HC157D into a powered system.