Texas Instruments SN74HC158NSR

Overview

SN74HC158NSR from Texas Instruments is a high-speed CMOS 4-bit 2-to-1 data selector/multiplexer with inverted outputs, operating across 2 V to 6 V supply range. It features ±6-mA output drive at 5 V, typical propagation delay of 11 ns (VCC = 6 V, CL = 50 pF), and supports up to 15 LSTTL loads. Used in digital logic routing, bus selection, and address/data path control in industrial control and instrumentation systems.

For engineers reviewing the SN74HC158NSR datasheet, SN74HC158NSR pinout, SN74HC158NSR application, or SN74HC158NSR equivalent, key selection criteria include its dual-input 4-bit multiplexing capability, active-low enable (G), A/B select control, and guaranteed inverted output polarity - critical for level-sensitive decoding and signal inversion in synchronous logic designs.

Technical Context

The SN74HC158NSR implements four independent 2:1 multiplexer gates, each selecting between two input sources (A or B) based on the A/B select line and enabled by the common strobe (G) input. All outputs are inverted - Y = NOT[(A AND NOT G AND NOT A/B) OR (B AND NOT G AND A/B)].

It uses standard HC-series CMOS logic with Schmitt-trigger noise immunity on control inputs (G and A/B), operates over −40°C to +85°C, and maintains consistent timing across VCC = 2 V–6 V. Input transition times are specified down to 400 ns (VCC = 6 V), ensuring robust operation with slow-rising control signals.

Key Specifications

Pinout & Package

SOP-16 (NS package), 10.4 mm × 5.3 mm body, 1.27 mm pitch, 2.00 mm max height, RoHS-compliant NiPdAu lead finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC158NSR, SN74HCT158N offers improved noise immunity in noisy 5 V environments but consumes ~2× more quiescent current; 74LCX158MTCX delivers superior speed and efficiency at 3.3 V but lacks 5 V tolerance and requires PCB redesign due to TSSOP-16 pitch difference.

Availability

SN74HC158NSR is available at Aetrix Electronics and suitable for industrial control, test equipment, and embedded microcontroller interface applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for SN74HC158NSR 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 decades of experience in high-reliability logic IC design and manufacturing.

The SN74HC158NSR belongs to TI's 74HC logic family - engineered for universal compatibility across 2–6 V systems, emphasizing low power, predictable timing, and robust noise immunity in industrial and commercial applications.

FAQ

What is the logic function implemented by SN74HC158NSR?

The SN74HC158NSR implements four independent 2:1 data selectors with inverted outputs. Each output Yn equals NOT[(An AND NOT G AND NOT A/B) OR (Bn AND NOT G AND A/B)], meaning it passes the selected input (A or B) only when G is LOW and inverts the result. This is distinct from non-inverting multiplexers like the SN74HC157.

Can SN74HC158NSR operate reliably at 3.3 V supply?

Yes, SN74HC158NSR is fully specified for 2 V to 6 V operation, including 3.3 V. At VCC = 3.3 V, it delivers ≥4 mA output drive, VIH ≤ 2.31 V, VIL ≥ 1.09 V, and typical tpd ≈ 14 ns (CL = 50 pF), making it suitable for mixed-voltage 3.3 V/5 V system interfaces without level translation.

What happens to outputs when the G (strobe) input is HIGH?

When G is HIGH, all four outputs (1Y–4Y) are forced HIGH regardless of A/B select state or input values. This is a three-state-equivalent behavior achieved via active-HIGH disable - useful for bus contention avoidance and hierarchical enable schemes in multi-device systems.

Is SN74HC158NSR pin-compatible with SN74HC157?

No, SN74HC158NSR is not pin-compatible with SN74HC157. While both are 4-bit 2:1 multiplexers, SN74HC157 has non-inverting outputs and different pin assignments (e.g., SN74HC157 places G on pin 1, whereas SN74HC158NSR places A/B there). Direct replacement requires PCB redesign and logic inversion in firmware or downstream circuitry.

Does SN74HC158NSR require external pull-up or pull-down resistors on unused inputs?

Yes - per TI's SCBA004 application report, all unused inputs (including G and A/B) must be tied to VCC or GND. Floating CMOS inputs cause increased ICC, erratic switching, and potential device damage due to shoot-through current; no internal pull-ups/pull-downs are provided on SN74HC158NSR.