Texas Instruments SN54HC157J

Overview

SN54HC157J from Texas Instruments is a high-speed CMOS 2-to-1 quad data selector/multiplexer in a 16-pin CDIP package, operating from −55°C to 125°C with 2 V–6 V supply voltage, 11 ns typical propagation delay at 6 V, ±6-mA output drive, and true-data routing for four parallel bits.

For engineers reviewing the SN54HC157J datasheet, SN54HC157J pinout, SN54HC157J application, or SN54HC157J equivalent, this device serves as a radiation-tolerant, military-grade multiplexer for deterministic signal routing in avionics, test equipment, and hardened digital control systems where wide temperature range and LSTTL-compatible drive are required.

Technical Context

The SN54HC157J implements four independent 2:1 multiplexers sharing a common select (A/B) and strobe (G) input, enabling synchronous selection of one of two 4-bit data sources. Each output (1Y–4Y) presents true (non-inverted) logic levels with active-low enable via G.

Its architecture uses buffered CMOS gates with rail-to-rail output swing, low input current (≤1 µA), and TTL-compatible input thresholds. The device supports fan-out of up to 15 LSTTL loads and maintains stable operation across its full military temperature range without derating.

Key Specifications

Pinout & Package

SN54HC157J is housed in a 16-pin Ceramic Dual In-line Package (CDIP-J), hermetically sealed for moisture resistance and thermal stability in harsh environments.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC157N and SN54LS157J, the SN54HC157J uniquely delivers CMOS efficiency, military temperature resilience, and hermetic reliability-making it the sole choice for high-reliability systems where long-term parametric stability under thermal stress is non-negotiable.

Availability

SN54HC157J is available at Aetrix Electronics and suitable for avionics data switching, automated test equipment signal routing, radiation-hardened control logic requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SN54HC157J 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 IC design.

The SN54HC157J belongs to TI's military-grade HC logic family, engineered for deterministic performance in defense, aerospace, and critical infrastructure applications where environmental robustness and long-term supply assurance are essential.

FAQ

What is the maximum clock frequency supported by SN54HC157J in a synchronous multiplexing application?

The SN54HC157J has a typical propagation delay of 11 ns at 6 V with 50-pF load, supporting reliable operation up to approximately 20 MHz in synchronous data-path applications. For guaranteed timing margins, designers should apply worst-case tpd values (32 ns at 6 V, CL = 50 pF) and verify setup/hold times against their controller's clock edge alignment. The SN54HC157J does not include internal clock circuitry and relies on externally generated control signals.

Does SN54HC157J require external pull-up or pull-down resistors on unused inputs?

Yes, all unused inputs of the SN54HC157J-including A/B, G, and any unconnected data lines-must be held at VCC or GND to prevent floating states that cause excessive ICC, increased noise susceptibility, and potential logic contention. TI's application report SCBA004 explicitly mandates this practice for proper CMOS device operation and reliability across the full −55°C to +125°C range.

Can SN54HC157J operate reliably at 2.5 V supply voltage?

Yes, the SN54HC157J is fully specified for operation down to 2 V, including guaranteed VIH/VIL thresholds, output drive, and propagation delay at 2.5 V. At this voltage, typical tpd increases to ~63 ns (CL = 50 pF), and output drive reduces to ±1.2 mA, but all logic functions remain valid and compliant with HC-series specifications per the SCLS113D datasheet.

Is SN54HC157J pin-compatible with SN74HC157 in the same package variant?

Yes, SN54HC157J and SN74HC157 share identical pinout, logic function, and electrical behavior in matching packages (e.g., J vs N). However, SN54HC157J is qualified for −55°C to +125°C and built to QML Class V standards, whereas SN74HC157N is commercial-grade (−40°C to +85°C); no PCB changes are needed when substituting within the same package footprint, but environmental validation remains required.

What is the meaning of "NC" pins in the SN54HC157J FK-package top view diagram?

In the LCCC (FK) package variant of SN54HC157J, "NC" denotes No Internal Connection - these pins are physically present but electrically isolated from the die. They must not be connected to VCC, GND, or signals, as doing so may compromise hermeticity or induce parasitic coupling. The CDIP (J) package used for SN54HC157J contains no NC pins; all 16 pins are functional per the standard pinout.