Texas Instruments SN74HC138PWRG4

Overview

SN74HC138PWRG4 from Texas Instruments is a 3-line to 8-line decoder/demultiplexer in a 16-pin TSSOP package, operating from 2 V to 6 V, with typical propagation delay of 15 ns at 6 V, ±4-mA output drive at 5 V, and active-low outputs enabling memory decoding and LED matrix column selection in industrial control systems.

For engineers reviewing the SN74HC138PWRG4 datasheet, SN74HC138PWRG4 pinout, SN74HC138PWRG4 application, or SN74HC138PWRG4 equivalent, this page delivers verified electrical specs, functional mode behavior, thermal metrics for TSSOP-16, and real-world implementation guidance for high-speed address decoding and demultiplexing tasks.

Technical Context

The SN74HC138PWRG4 implements combinational logic decoding using three binary select inputs (A, B, C) and three enable terminals (G1 active-high; G2A, G2B active-low), where all outputs remain high unless all enables are asserted and exactly one output line is driven low. Its CMOS architecture ensures rail-to-rail input compatibility and balanced output drive across the full 2–6 V supply range.

Propagation delay is supply-voltage dependent: 38 ns max at 6 V over temperature, with output transition times as low as 16 ns. The device supports cascading via enable pins-e.g., two SN74HC138PWRG4 units can form a 4-to-16 decoder without external inverters-making it suitable for hierarchical memory addressing and I/O expansion.

Key Specifications

Pinout & Package

TSSOP-16 package (5.00 mm × 4.40 mm body size, 0.65 mm pitch), lead finish NIPDAU, moisture sensitivity level (MSL) Level-1 (unlimited floor life at ≤30 °C/60% RH).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 3-to-8 decoder applications.

Compared with SN74HCT138PWRE4 and 74LV138PW,118, the SN74HC138PWRG4 offers optimal balance of speed (15 ns typ), power (80 µA max), and voltage flexibility (2–6 V) for mainstream industrial control, making it the default choice unless TTL compatibility or sub-2 V operation is required.

Availability

SN74HC138PWRG4 is available at Aetrix Electronics and suitable for industrial memory decoding, LED matrix driving, factory automation I/O expansion, and power infrastructure sequencing requiring stable component supply and long-term production continuity.

Supply support for SN74HC138PWRG4 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 connectivity technologies, with decades of experience in industrial-grade logic and interface solutions.

The SN74HC138PWRG4 belongs to TI's 74HC logic family, designed for high-speed, low-power decoding and demultiplexing in industrial, automotive, and communications systems where reliability and wide supply tolerance are critical.

FAQ

What is the maximum operating frequency supported by the SN74HC138PWRG4?

The SN74HC138PWRG4 does not operate at a clock frequency-it is a combinational logic device with propagation delay as its key timing parameter. At 6 V supply, its maximum tpd is 38 ns, supporting effective address decode rates up to ~26 MHz in synchronous systems. For reliable operation, ensure input transitions meet the specified Δt/Δv limits (400 ns max at 6 V) to avoid metastability or increased jitter.

Can the SN74HC138PWRG4 be used as a demultiplexer, and how is data routed?

Yes, the SN74HC138PWRG4 functions as a 1-to-8 demultiplexer when one enable pin (e.g., G1) is used as the data input and A/B/C serve as select lines. With G2A and G2B held low, the logic level applied to G1 appears inverted on the selected Yx output (active-low), while all other outputs remain high. This configuration enables serial-to-parallel data distribution in communication interfaces and test equipment.

Does the SN74HC138PWRG4 require external pull-up resistors on its outputs?

No-outputs are push-pull CMOS and actively drive both HIGH and LOW states. External pull-ups are unnecessary and may cause contention or excessive current draw when an output is driven low. Pull-ups should only be added if interfacing with open-drain inputs or legacy TTL loads requiring stronger high-side drive, which is not typical for SN74HC138PWRG4 applications.

How does the enable logic work across G1, G2A, and G2B in the SN74HC138PWRG4?

All three enables must be simultaneously satisfied for any output to go active-low: G1 must be HIGH, and both G2A and G2B must be LOW. If any enable condition fails, all eight outputs (Y0–Y7) are forced HIGH. This three-input enable scheme simplifies cascading-for example, connecting Y0 of a master SN74HC138PWRG4 to G1 of a slave unit creates a 4-to-16 decoder with no external logic.

Is the SN74HC138PWRG4 RoHS compliant and what is its MSL rating?

Yes, the SN74HC138PWRG4 is RoHS compliant (lead-free, NIPDAU finish) and rated MSL Level-1 at 260 °C peak reflow, meaning it has unlimited floor life when stored at ≤30 °C/60% RH. This allows standard SMT assembly without baking, simplifying manufacturing for high-reliability industrial PCBs.