Texas Instruments SN74HC139NS

Overview

SN74HC139NS from Texas Instruments is a dual 2-line-to-4-line decoder/demultiplexer in SO (SOP) package, operating across 2 V to 6 V supply range, delivering typical propagation delay of 10 ns at 5 V, ±4-mA output drive, and low ICC of 80 μA max - used for high-speed memory decoding and data routing in industrial control logic and address selection circuits.

For engineers reviewing the SN74HC139NS datasheet, SN74HC139NS pinout, SN74HC139NS application, or SN74HC139NS equivalent, key selection criteria include active-low enable architecture, dual independent decoder channels, LSTTL-load compatibility (up to 10 loads), and SO-16 thermal performance (RθJA = 64°C/W).

Technical Context

The SN74HC139NS implements two fully buffered, independent 2-to-4 decoders sharing no internal signal paths. Each channel features an active-low enable (G) input that forces all four outputs high when asserted, enabling clean cascading and demultiplexing control.

Its CMOS HC-family design ensures TTL-compatible input thresholds, rail-to-rail output swing, and low static current (≤1 μA input leakage). Switching behavior is characterized under CL = 50 pF with tpd as low as 10 ns (VCC = 6 V, TA = 25°C) and output transition time (tt) down to 6 ns.

Key Specifications

Pinout & Package

SN74HC139NS uses a 16-pin Small Outline Package (SO/SOP) with 6.20 mm × 5.30 mm body size, 1.27 mm lead pitch, and 2.00 mm max height per TI NS0016A drawing. Thermal resistance is RθJA = 64°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual 2-to-4 decoder applications.

Compared with SN74HCT139N and 74AC139M, SN74HC139NS delivers optimal balance of low power (80 μA), robust 2–6 V operation, and 10 ns timing - making it ideal for cost-sensitive, thermally constrained industrial controllers where strict TTL compatibility is unnecessary.

Availability

SN74HC139NS is available at Aetrix Electronics and suitable for industrial control logic, memory address decoding, and peripheral select applications requiring stable component supply and long-term production continuity.

Supply support for SN74HC139NS 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 over 50 years of innovation in industrial, automotive, and communications markets.

The SN74HC139NS belongs to TI's HC-series high-speed CMOS logic family, designed specifically for low-power, high-noise-immunity digital signal routing in memory systems and programmable logic interfaces.

FAQ

What is the maximum clock frequency supported by SN74HC139NS for reliable decoding?

SN74HC139NS does not operate on a clock; it is a combinational logic device with propagation delay-based timing. Its 10 ns typical tpd at 5 V supports reliable operation in address decode paths with setup/hold windows ≥15 ns. For 50-MHz bus systems, SN74HC139NS introduces negligible delay versus memory access time - verified in TI SCLS108E characterization at CL = 50 pF.

Can SN74HC139NS drive LEDs directly without current-limiting resistors?

No. SN74HC139NS outputs are rated for ±4 mA at 5 V and must not sink/source more than 25 mA continuous per output (absolute max). Driving even a low-current LED (e.g., 2 mA) requires a series resistor to limit current and prevent damage. TI specifies VOH/VOL only under defined load conditions - direct LED connection violates recommended operating conditions.

Is SN74HC139NS pin-compatible with SN74LS139N?

Yes - SN74HC139NS and SN74LS139N share identical pin assignments and functional block diagram per TI documentation. However, SN74HC139NS uses CMOS inputs (VIH = 3.15 V @ 4.5 V) versus TTL inputs (VIH = 2 V), so direct substitution requires verifying driving source voltage levels meet HC thresholds.

Does SN74HC139NS require external pull-up resistors on its outputs?

No. SN74HC139NS has totem-pole CMOS outputs capable of actively driving high or low. Pull-ups are unnecessary unless open-drain emulation is needed. TI's datasheet confirms VOH ≥4.4 V at 4.5 V VCC with IOH = –4 mA - confirming full rail-to-rail push-pull capability.

What is the meaning of "NS" in SN74HC139NS and how does it differ from "N" or "D" suffixes?

The "NS" suffix denotes Texas Instruments' Small Outline Package (SOP) variant - 16-pin, 6.20 mm × 5.30 mm body, gull-wing leads. It differs from "N" (PDIP, through-hole) and "D" (SOIC, wider 9.90 mm body). All share identical logic function but differ in thermal performance (RθJA = 64°C/W for NS vs. 67°C/W for N) and mounting method.