Texas Instruments SN74AHCT139DBR

Overview

SN74AHCT139DBR from Texas Instruments is a dual 2-line-to-4-line decoder/demultiplexer in SSOP-16 package, operating at 4.5–5.5 V, with propagation delays as low as 1 ns (t_PLH/t_PHL at 15 pF), TTL-compatible inputs, and ±8 mA output drive-designed for high-speed memory decoding and data-routing systems in industrial control and embedded logic boards.

For engineers reviewing the SN74AHCT139DBR datasheet, SN74AHCT139DBR pinout, SN74AHCT139DBR application, or SN74AHCT139DBR equivalent, key selection considerations include its dual-decoder architecture with independent active-low enables (1G, 2G), guaranteed 85°C operation, SSOP thermal performance (θ_JA = 82°C/W), and compatibility with 5-V TTL-level signal chains.

Technical Context

The SN74AHCT139DBR implements two independent 2-to-4 decoders, each with binary-select inputs (A, B), active-low enable (G), and four active-low decoded outputs (Y0–Y3). Its fully buffered inputs present only one normalized load, minimizing fanout burden on upstream drivers.

It uses standard positive-logic decoding with active-low outputs and supports demultiplexing via the G input as a data line. All logic thresholds are TTL-voltage compatible (V_IL = 0.8 V, V_VIH = 2 V), and output switching is characterized at 15 pF and 50 pF loads across –40°C to 85°C.

Key Specifications

Pinout & Package

SN74AHCT139DBR is housed in a 16-pin SSOP (Shrink Small Outline Package) with 0.65 mm lead pitch, 7.4 mm × 5.3 mm body, and 2.0 mm max height per JEDEC MO-150. Pin 1 is marked by a corner chamfer and located in Quadrant Q1 of the tape reel.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC139DR and 74LVC139AD,118, the SN74AHCT139DBR uniquely delivers TTL-compatible inputs, 5-V operation, and sub-10 ns propagation in a production-ready SSOP package-making it the optimal choice for upgrading legacy 5-V logic without redesigning signal integrity or power delivery.

Availability

SN74AHCT139DBR is available at Aetrix Electronics and suitable for industrial control panels, embedded instrumentation, and legacy-system upgrades requiring stable component supply, long-lifecycle support, and guaranteed SSOP-16 packaging consistency.

Supply support for SN74AHCT139DBR 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.

The SN74AHCT139DBR belongs to TI's AHCT advanced high-speed CMOS logic family, engineered specifically for seamless 5-V TTL interoperability and high-performance memory decoding in cost-sensitive industrial applications.

FAQ

What is the maximum clock frequency supported by SN74AHCT139DBR?

The SN74AHCT139DBR is not a clocked device-it has no internal clock and operates asynchronously. Its usable signal frequency depends on propagation delay and load capacitance. With 15 pF load, worst-case t_PD is 8.5 ns, supporting clean edge transitions up to ~60 MHz in cascaded logic paths. For SN74AHCT139DBR, timing is governed by input transition rates (≤20 ns/V) and output loading, not a clock domain.

Can SN74AHCT139DBR drive LEDs directly?

Yes-SN74AHCT139DBR outputs can sink up to 8 mA (I_OL) and source up to 8 mA (I_OH) at V_CC = 5 V. When configured with active-low outputs, it can directly drive standard 5-mm LEDs (2 mA typical) with a series resistor (e.g., 330 Ω for ~10 mA peak). Do not exceed 8 mA per output or 75 mA total V_CC/GND current as specified in absolute maximum ratings.

Is SN74AHCT139DBR pin-compatible with SN74LS139N?

No-SN74AHCT139DBR and SN74LS139N share identical logic function and pin numbering (16-pin DIP/SSOP), but differ in electrical behavior: SN74LS139N uses bipolar TTL with higher I_IL (-0.4 mA) and lower V_OH (~2.7 V), while SN74AHCT139DBR is CMOS with near-rail V_OH and µA-level I_I. They are functionally interchangeable in most designs, but SN74AHCT139DBR offers lower power and better noise margin. The SN74AHCT139DBR is not a drop-in replacement without verifying input loading and output voltage requirements.

Does SN74AHCT139DBR support mixed-voltage operation (e.g., 3.3-V inputs)?

No-SN74AHCT139DBR requires V_CC = 4.5–5.5 V and is designed for TTL-compatible inputs (V_IH ≥ 2 V, V_IL ≤ 0.8 V). While 3.3-V logic may meet V_IH margin, it violates recommended operating conditions and risks unreliable switching at temperature extremes. For 3.3-V systems, use 74LVC139 or level translators. SN74AHCT139DBR must operate at 5 V for guaranteed specification compliance.

What is the meaning of "HB139" marking on SN74AHCT139DBR?

"HB139" is the top-side marking laser-etched on the SN74AHCT139DBR package per TI's standard ordering information. It identifies the device as part of the AHCT139 family and distinguishes it from other variants (e.g., "AHCT139" on SOIC versions). This marking is consistent across all active SSOP, TVSOP, and TSSOP variants of SN74AHCT139 and is used for traceability and visual inspection-not functional differentiation. The full SN74AHCT139DBR part number remains the authoritative identifier.