Texas Instruments SN74AHC157NS

Overview

SN74AHC157NS from Texas Instruments is a quad 2-input multiplexer IC with non-inverting outputs, designed for high-speed data routing in digital logic systems. It features active-low enable (E), common select (S), 8 data inputs (1I0–4I0 and 1I1–4I1), and 4 true outputs (1Y–4Y), operating across 2.0–5.5 V supply range with propagation delays as low as 3.2 ns at 5 V/15 pF. It is widely used in register-to-bus data transfer and irregular combinational logic generation.

For engineers reviewing the SN74AHC157NS datasheet, SN74AHC157NS pinout, SN74AHC157NS application, or SN74AHC157NS equivalent, this page delivers verified functional behavior, validated pin mapping for SO-16 package, real-world timing specs under load, CMOS-level input compatibility, and direct alternatives for logic design continuity and BOM flexibility.

Technical Context

The SN74AHC157NS implements four independent 2:1 multiplexers sharing one select (S) and one active-low enable (E) control line. Its logic equations are 1Y = E × (1I1 × S + 1I0 × S̅), and similarly for 2Y–4Y - confirming true (non-inverting) output behavior distinct from the inverting 74AHC158.

It operates strictly within CMOS input voltage thresholds (VIH ≥ 3.85 V at VCC = 5.5 V; VIL ≤ 1.65 V), supports rail-to-rail output swing, and maintains balanced propagation delays across all channels. Input clamping current exceeds ±20 mA, and ESD protection meets HBM >2000 V per JESD22-A114E.

Key Specifications

Pinout & Package

SN74AHC157NS is supplied in a 16-pin SOIC (SO-16) package with 3.9 mm body width (JEDEC MS-012, TI package code NS). Pin 1 is index-marked; pin 8 is GND; pin 16 is VCC.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad 2-input multiplexer applications.

Compared with SN74AHCT157NS and 74LVC157PW, SN74AHC157NS uniquely supports both 3.3 V and 5 V operation with CMOS input thresholds, making it the most flexible option for mixed-supply systems requiring guaranteed noise immunity and extended temperature capability.

Availability

SN74AHC157NS is available at Aetrix Electronics and suitable for industrial automation controllers, automotive body control modules, and test equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SN74AHC157NS 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.

SN74AHC157NS belongs to the AHC advanced high-speed CMOS logic family, engineered for low-power, high-noise-immunity digital interfacing in industrial, automotive, and communications infrastructure applications.

FAQ

What is the logic function implemented by SN74AHC157NS?

SN74AHC157NS implements four independent 2:1 multiplexers with a shared select (S) and active-low enable (E). Each output Yn equals E̅ × (In1 × S + In0 × S̅), delivering true (non-inverting) outputs. This structure allows simultaneous selection of four bits from two 4-bit sources - ideal for register file access, bus switching, and combinational logic synthesis. The SN74AHC157NS differs from the 74AHC158 by omitting output inversion.

Does SN74AHC157NS support 3.3 V operation?

Yes, SN74AHC157NS is fully specified for 3.3 V operation (VCC = 3.0 V to 3.6 V), with typical propagation delay of 4.4 ns and output drive of ±4 mA at 3 V. Its CMOS input thresholds scale with VCC, ensuring reliable logic recognition at 3.3 V. This makes SN74AHC157NS suitable for mixed-voltage systems interfacing with both 3.3 V and 5 V logic domains without external level shifters.

What happens to the outputs of SN74AHC157NS when the enable pin (E) is HIGH?

When the enable input (E) is driven HIGH, all four outputs (1Y–4Y) of SN74AHC157NS are forced LOW regardless of the states of S or any data inputs. This active-low enable behavior provides clean, predictable output disable - essential for bus isolation, power sequencing, and preventing contention during system reset or standby modes. The SN74AHC157NS does not enter high-impedance (tri-state) mode; outputs actively drive LOW.

Can SN74AHC157NS be used as a function generator?

Yes, SN74AHC157NS can generate any four of the 16 possible 2-variable Boolean functions by fixing one variable as the select input (S) and assigning the other variable and its complement to the I0 and I1 inputs of each channel. For example, setting 1I0 = A, 1I1 = A̅ yields XOR; setting both to constants yields AND/OR/NOT variants. This capability is explicitly documented in the SN74AHC157NS datasheet and leveraged in compact logic replacement designs.

Is SN74AHC157NS pin-compatible with older TTL multiplexers?

SN74AHC157NS is pin-compatible with Low Power Schottky TTL (LSTTL) devices such as the 74LS157, sharing identical SO-16 pinout, logic function, and DC electrical interface. However, its CMOS inputs require higher VIH (≥3.85 V at 5 V) than TTL, so direct replacement is safe only when driving sources meet CMOS thresholds. For legacy TTL drivers, SN74AHCT157NS - with TTL-compatible inputs - is the recommended drop-in alternative.