Texas Instruments SN74HC158NG4

Overview

SN74HC158NG4 from Texas Instruments is a high-speed CMOS 4-bit 2-to-1 data selector/multiplexer with active-low strobe (G) and inverted outputs. It operates across 2 V to 6 V, delivers 11 ns typical propagation delay at 6 V, supports ±6-mA output drive, and drives up to 15 LSTTL loads - used in digital logic routing, address/data bus selection, and control signal multiplexing in industrial microcontroller interfaces.

For engineers reviewing the SN74HC158NG4 datasheet, SN74HC158NG4 pinout, SN74HC158NG4 application, or SN74HC158NG4 equivalent, key selection criteria include its dual-input 4-channel architecture, guaranteed inverted output polarity, wide VCC range, low ICC (80 µA max), and compatibility with legacy TTL and modern CMOS systems requiring deterministic data path selection.

Technical Context

The SN74HC158NG4 implements four independent 2:1 multiplexer gates, each selecting between A or B input based on the A/B select line, with all outputs enabled or disabled collectively by the active-low G strobe. Its logic diagram confirms full inversion at Y outputs - no non-inverted path exists within the device.

It uses standard HC-series CMOS process technology, delivering rail-to-rail output swing, high noise immunity (VIH = 3.15 V min at VCC = 4.5 V), and input transition time tolerance down to 400 ns at 6 V - enabling reliable operation in mixed-voltage and noisy industrial environments without external level-shifting.

Key Specifications

Pinout & Package

SN74HC158NG4 is supplied in a 16-pin plastic dual in-line package (PDIP-N), 19.1 mm × 6.6 mm body, 0.635 mm lead pitch, through-hole mountable. Pin 1 is located at the left end of the top row (notch-up orientation).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC158NG4, SN74HC157N offers identical functionality minus inversion - ideal for logic-consistent upgrades - while 74LVC157APW trades voltage flexibility for speed and size, limiting use to strictly 3.3 V applications with space constraints.

Availability

SN74HC158NG4 is available at Aetrix Electronics and suitable for industrial control systems, test equipment signal routing, and microcontroller peripheral interfacing requiring stable component supply, long-term obsolescence management, and RoHS-compliant through-hole logic solutions.

Supply support for SN74HC158NG4 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 ICs, with decades of heritage in industry-standard logic families including 74HC.

The SN74HC158NG4 belongs to TI's 74HC high-speed CMOS logic series, designed specifically for industrial and automotive applications demanding wide voltage operation, low power, and robust noise immunity in real-world environments.

FAQ

What is the function of the G (strobe) pin on the SN74HC158NG4?

The G pin on the SN74HC158NG4 is an active-low enable input. When G is HIGH, all four Y outputs enter high-impedance (Hi-Z) state regardless of A/B or data inputs. Only when G is LOW does the device perform normal 2:1 multiplexing with inverted outputs. This enables bus-sharing and hierarchical enable control in multi-device systems.

Does the SN74HC158NG4 support 3.3 V operation?

Yes, the SN74HC158NG4 fully supports 3.3 V operation within its specified 2 V to 6 V supply range. At VCC = 3.3 V, it maintains guaranteed VIH (≥2.31 V), VIL (≤1.09 V), and tpd (≤19 ns typical), making it suitable for mixed-voltage designs interfacing 3.3 V MCUs with 5 V peripherals - no level shifting required.

Can unused inputs on the SN74HC158NG4 be left floating?

No - all unused inputs on the SN74HC158NG4 must be tied to either VCC or GND. Floating CMOS inputs cause increased ICC, potential oscillation, and ESD susceptibility. TI's application report SCBA004 explicitly mandates this for proper device operation and reliability, especially in industrial temperature ranges.

Is the SN74HC158NG4 pin-compatible with the SN74HC157N?

Yes, the SN74HC158NG4 and SN74HC157N share identical pinout, package dimensions, and electrical timing - but differ critically in output polarity: SN74HC158NG4 outputs are inverted, while SN74HC157N outputs are non-inverted. They are physically interchangeable but functionally distinct; substitution requires logic-level verification.

What is the maximum capacitive load the SN74HC158NG4 can drive reliably?

The SN74HC158NG4 is characterized for CL = 50 pF and 150 pF loads in its datasheet. At 50 pF, tpd remains ≤27 ns (max) at 6 V; at 150 pF, tpd increases to ≤45 ns. For reliable edge integrity beyond 150 pF, external buffer drivers are recommended - the device itself is not rated for sustained >200 pF loading per output.