Texas Instruments SN74HC158PWT

Overview

SN74HC158PWT from Texas Instruments is a 4-bit dual-input inverting data selector/multiplexer in TSSOP-16 package, operating from 2 V to 6 V, delivering 11 ns typical propagation delay at 6 V and ±6-mA output drive at 5 V. It routes one of two 4-bit data sources to inverted outputs under control of a common strobe (G) and select (A/B) inputs, used in digital logic routing, address decoding, and bus multiplexing in industrial control and instrumentation systems.

For engineers reviewing the SN74HC158PWT datasheet, SN74HC158PWT pinout, SN74HC158PWT application, or SN74HC158PWT equivalent, key selection considerations include its 2–6 V wide supply range, 15-LSTTL load drive capability, low 80-µA max ICC, guaranteed 11 ns tpd at 6 V, and TSSOP-16 thermal performance (θJA = 108°C/W).

Technical Context

The SN74HC158PWT implements four independent 2:1 multiplexer channels with active-low enable (G) and shared select (A/B), each producing inverted outputs (1Y–4Y). Its CMOS architecture ensures rail-to-rail input thresholds (VIH = 3.15 V min at VCC = 4.5 V; VIL = 1.35 V max), low input current (≤1 µA), and robust noise immunity across −40°C to 85°C operation.

All inputs are buffered with Schmitt-trigger-like hysteresis per TI's design practice for HC-series devices, and unused inputs must be tied to VCC or GND to prevent floating-node oscillation and excessive ICC. The device does not support hot-swap or I²C-style open-drain operation-outputs are push-pull with symmetrical sourcing/sinking capability.

Key Specifications

Pinout & Package

TSSOP-16 package (PW), 4.4 mm × 5.0 mm body, 0.65 mm pitch, 1.2 mm max height, JEDEC MO-153 compliant, lead-free (NIPDAU), MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 4-bit dual-input multiplexer applications.

Compared with SN74HC158PWT, SN74HC157PWR preserves full electrical and mechanical compatibility while reversing output polarity, whereas 74LVC157APW trades voltage range for higher speed and lower static power-making it ideal for next-gen 3.3 V platforms but incompatible with legacy 5 V infrastructure.

Availability

SN74HC158PWT is available at Aetrix Electronics and suitable for industrial control, test instrumentation, and automotive body electronics requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for SN74HC158PWT 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 founded in 1930, specializing in analog, embedded processing, and logic ICs with broad industrial, automotive, and consumer reach.

The SN74HC158PWT belongs to TI's 74HC logic family-designed for high-speed, low-power, pin-compatible upgrades to legacy TTL, targeting cost-sensitive, space-constrained digital control applications.

FAQ

What is the function of the G (strobe) pin on the SN74HC158PWT?

The G pin is an active-low enable input. When G is high, all four outputs (1Y–4Y) enter high-impedance state regardless of A/B or data inputs. When G is low, the device operates normally, routing the selected input (A or B) to each output with inversion. This allows bus isolation and synchronized channel activation in multi-device systems - a critical feature in the SN74HC158PWT's role as a controlled data router.

Can SN74HC158PWT operate reliably at 3.3 V supply?

Yes. The SN74HC158PWT is fully specified from 2 V to 6 V, including 3.3 V. At VCC = 3.3 V, it delivers guaranteed VIH = 2.31 V min and VIL = 0.99 V max, providing >0.8 V noise margin. Propagation delay increases to ~17 ns (typ), and output drive reduces to ±4 mA - still sufficient for driving 10+ LSTTL loads. This makes SN74HC158PWT interoperable across 3.3 V and 5 V domains without level translation.

Does SN74HC158PWT support hot insertion or live swapping?

No. The SN74HC158PWT lacks hot-swap protection circuitry such as power-up sequencing control, Ioff partial power-down, or bus-hold. Applying VCC while inputs are driven can cause latch-up or excessive ICC. TI recommends powering the SN74HC158PWT before applying input signals and using series resistors (100 Ω) on all inputs if live insertion is unavoidable - a limitation inherent to standard HC-series logic, not unique to SN74HC158PWT.

How does the inverting output behavior of SN74HC158PWT affect system timing?

The SN74HC158PWT inverts all outputs, meaning a logic-high input produces a logic-low output and vice versa. This adds no additional propagation delay beyond the base tpd (11 ns typ at 6 V) - inversion is implemented within the same gate stage. System timing analysis must account for the logical complement, especially when interfacing with edge-triggered flip-flops or asynchronous reset paths, but setup/hold windows remain unchanged versus non-inverting equivalents like SN74HC157PWR.

What is the maximum capacitive load the SN74HC158PWT can drive while maintaining 11 ns tpd?

The 11 ns typical propagation delay for SN74HC158PWT is specified at CL = 50 pF. As load capacitance increases, tpd degrades linearly: at CL = 150 pF, tpd rises to 33 ns (typ at 6 V). For designs requiring ≤15 ns delay, total node capacitance-including PCB trace, probe, and downstream input-must stay below 75 pF. Layout best practices (short traces, minimized stubs, proper grounding) are essential to preserve SN74HC158PWT's timing performance in high-speed routing applications.