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Texas Instruments SN74AHCT139NSR
- Part No.:
- SN74AHCT139NSR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74AHCT139NSR.pdf
- Description:
- IC DECODER/DEMUX 1 X 2:4 16SO
- Quantity:
- Payment:
- Shipping:
Inventory:3,157
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Product details
Overview
SN74AHCT139NSR from Texas Instruments is a dual 2-line-to-4-line decoder/demultiplexer in a 16-pin SOP (NS) package, operating at 4.5–5.5 V, with propagation delays as low as 1 ns (tPLH/tPHL at 15 pF), TTL-compatible inputs, and ±8 mA output drive. It serves as a high-speed memory decoder or data-routing IC in address decoding paths of microcontroller-based systems and FPGA peripheral interfaces.
For engineers reviewing the SN74AHCT139NSR datasheet, SN74AHCT139NSR pinout, SN74AHCT139NSR application, or SN74AHCT139NSR equivalent, key selection considerations include its dual-decoder architecture with independent active-low enables (1G, 2G), guaranteed 1 ns minimum propagation delay at 5 V/15 pF, SOP-16 thermal resistance (θJA = 64°C/W), and compatibility with legacy TTL logic levels in mixed-voltage digital systems.
Technical Context
The SN74AHCT139NSR implements two independent 2-to-4 line decoders, each with separate active-low enable (G) and binary select inputs (A, B), producing four active-low decoded outputs (Y0–Y3). Its fully buffered inputs present only one normalized TTL load, minimizing fanout burden on upstream drivers.
It features dual enable inputs enabling cascading for larger decoding (e.g., 3-to-8 or 4-to-16) without external gating, and supports demultiplexing by using G as a data input while A/B select output routing - all within a single 16-pin SOP package with no internal connections on pins 3, 8, 11, and 15.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - Ensures stable operation across standard 5 V supply rails with ±10% tolerance, compatible with legacy 5 V TTL and CMOS systems. |
| Propagation Delay (tPLH/tPHL) | 1 ns (min) / 8.5 ns (max) at VCC = 5 V, CL = 15 pF - Enables sub-10 ns address decode latency critical for high-speed memory access timing budgets. |
| Output Drive (IOL/IOH) | ±8 mA - Sufficient to directly drive multiple 74-series TTL inputs or small capacitive loads without buffering. |
| Input Voltage Compatibility | TTL-level (VIL ≤ 0.8 V, VIH ≥ 2 V) - Allows direct interfacing with older 5 V TTL outputs without level-shifting circuitry. |
| ESD Protection | 2000-V HBM, 200-V MM, 1000-V CDM - Meets industrial-grade robustness requirements for board-level handling and system integration. |
| Operating Temperature | –40°C to +85°C - Qualified for commercial and industrial ambient environments, including embedded control and instrumentation applications. |
| Package Thermal Resistance (θJA) | 64°C/W (SOP-NS) - Supports sustained operation at full output loading in compact PCB layouts without forced airflow. |
Pinout & Package
SOP-16 (NS) package: 5.3 mm × 10.2 mm body, 1.75 mm height, 0.65 mm lead pitch, gull-wing leads, RoHS-compliant NiPdAu finish, MSL Level-1 (unlimited floor life).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1G, 2G | Active-low enable inputs | Each controls one decoder independently; low enables decoding, high forces all Y outputs high - enables cascading and data gating. |
| 1A, 1B / 2A, 2B | Binary address inputs | Two-bit select lines per decoder; determine which of four Y outputs goes low (active-low decoded output). |
| 1Y0–1Y3 / 2Y0–2Y3 | Active-low decoded outputs | Four per decoder; asserted low when corresponding G is low and A/B match - used for chip select, segment enable, or I/O gating. |
| VCC (Pin 16) | Positive supply | 5 V nominal power rail; decoupling capacitor required near pin for noise immunity during fast switching. |
| GND (Pin 8) | Ground reference | Common return path for all logic and output currents; must be low-impedance to minimize ground bounce. |
| Pins 3, 11, 15 | No internal connection (NC) | Not bonded internally; must remain unconnected on PCB - no routing or pull-up/pull-down allowed. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent decoders | Two complete 2-to-4 decoder blocks share only VCC and GND - eliminates need for two discrete packages in space-constrained designs. |
| Active-low enable with data routing capability | Enable (G) input functions as data input in demux mode - allows single-bit data distribution to four outputs under A/B control without extra logic. |
| Full TTL voltage compatibility | Guaranteed VIH ≥ 2 V and VIL ≤ 0.8 V - ensures reliable interfacing with 74LS, 74F, and other legacy TTL families without level shifters. |
| Low propagation delay variation | tPLH and tPHL differ by ≤ 0.5 ns (typ.) at 15 pF - minimizes skew between parallel decoded outputs critical for synchronous bus enable timing. |
| Latch-up immunity | >250 mA per JESD17 - prevents destructive latch-up during transient overvoltage or hot-insertion events in backplane or modular systems. |
Applications
| Memory Address Decoding | FPGA Peripheral Interface |
|---|---|
|
Use Scenario: Selecting one of four SRAM or EPROM chips in a microcontroller-based data acquisition system. IC Role / Device Role: Dual decoder provides two independent 2-bit address decode paths - one for memory bank selection, one for peripheral register mapping. Use Value: Sub-10 ns propagation delay ensures decoded chip-select signals arrive before memory access window closes, eliminating wait states. |
Use Scenario: Routing configuration data from an FPGA I/O bank to four distinct sensor interface ICs via shared control bus. IC Role / Device Role: Acts as a demultiplexer using 2G as serial data input and 2A/2B as clock-synchronized address bits. Use Value: Active-low outputs directly assert enable pins on sensor ICs with no external inverters, reducing component count and layout area. |
| Industrial PLC I/O Expansion | Legacy System Bus Arbitration |
|
Use Scenario: Expanding discrete I/O points in a programmable logic controller by enabling groups of optocoupler-driven output modules. IC Role / Device Role: Each decoder block selects four output banks; 1G/2G tied to PLC scan cycle flags for time-multiplexed activation. Use Value: TTL-compatible inputs accept direct connection to PLC's 5 V logic outputs, avoiding level translation and associated timing uncertainty. |
Use Scenario: Managing bus grant signals among four legacy ISA-style expansion cards sharing a common 8-bit data bus. IC Role / Device Role: Generates four mutually exclusive bus-enable signals from two master arbitration bits, with G inputs synchronized to bus clock. Use Value: Guaranteed 1 ns minimum delay prevents race conditions during bus handoff, ensuring deterministic arbitration timing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual 2-to-4 decoder applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AHCT139DR | SOIC-16 (D) package; θJA = 73°C/W vs. NS package's 64°C/W; identical electrical specs and pinout. | SOIC offers wider lead spacing (1.27 mm vs. 0.65 mm) - preferred for manual soldering or low-volume prototyping. | Select SN74AHCT139DR if board assembly uses through-hole rework or lacks fine-pitch SMT capability. |
| SN74AHCT139DBR | SSOP-16 (DB) package; θJA = 82°C/W; same logic function, but 5.3 mm × 6.2 mm footprint vs. NS's 5.3 mm × 10.2 mm. | SSOP provides smaller PCB area than SOP-NS but requires tighter stencil design and higher placement accuracy. | Choose SN74AHCT139DBR when board space is constrained and automated SMT placement is available. |
Compared with SN74AHCT139DR and SN74AHCT139DBR, the SN74AHCT139NSR delivers the best thermal performance (64°C/W) in a widely supported SOP footprint - making it optimal for thermally demanding, medium-volume industrial applications where reliability under continuous load matters most.
Availability
SN74AHCT139NSR is available at Aetrix Electronics and suitable for memory decoding, FPGA peripheral routing, industrial I/O expansion, and legacy bus arbitration requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for SN74AHCT139NSR 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 with over 90 years of analog and logic IC innovation, headquartered in Dallas, Texas, and serving automotive, industrial, and communications markets.
The SN74AHCT139NSR belongs to TI's AHCT logic family - engineered for high-speed 5 V TTL-compatible operation with low power consumption and robust noise immunity in legacy and mixed-signal digital systems.
FAQ
What is the maximum clock frequency supported by SN74AHCT139NSR in demultiplexer mode?
The SN74AHCT139NSR does not operate on a clock signal - it is combinational logic. Its usable data rate depends on propagation delay and system timing margins. With tPLH/tPHL ≤ 8.5 ns (max) at 15 pF, it supports effective demux rates up to ~60 MHz in well-designed layouts where setup/hold times are met. The SN74AHCT139NSR must be driven by stable address and data signals prior to any downstream sampling edge.
Can SN74AHCT139NSR drive LEDs directly?
Yes - the SN74AHCT139NSR can sink up to 8 mA per output (IOL = 8 mA), sufficient to illuminate low-current indicator LEDs (e.g., 2 mA @ 1.8 V forward voltage) with a series resistor. For higher-brightness or multi-LED loads, external buffer transistors are recommended. Always verify VOL ≤ 0.44 V at 8 mA to ensure adequate logic-low margin in the SN74AHCT139NSR.
Is SN74AHCT139NSR pin-compatible with older 74LS139 devices?
No - while functionally equivalent, the SN74AHCT139NSR has different DC characteristics and timing. Its inputs accept TTL voltages but outputs swing rail-to-rail (0 V / VCC), unlike 74LS139's lower-voltage TTL outputs. Also, SN74AHCT139NSR features NC pins (3, 8, 11, 15) not present in 74LS139, requiring PCB layout verification before drop-in replacement.
Does SN74AHCT139NSR require external pull-up resistors on its outputs?
No - the SN74AHCT139NSR has totem-pole outputs, not open-drain. Its Y outputs actively drive both high and low states. Pull-ups are unnecessary and would cause contention when outputs switch low. External pull-ups should only be used if interfacing with legacy circuits expecting wired-OR behavior - which requires redesigning the SN74AHCT139NSR's output stage.
What is the meaning of "NC" pins on SN74AHCT139NSR, and how should they be handled on the PCB?
Pins 3, 8, 11, and 15 are marked NC (No internal connection) in the SN74AHCT139NSR datasheet - they are not bonded to the die. These pins must remain unconnected on the PCB: no traces, vias, or components. Leaving them floating is safe; however, grounding them is not recommended as it may introduce unintended parasitic capacitance or ESD paths that affect adjacent signal integrity.
SN74AHCT139NSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHCT
- Package/Case:
- 16-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Decoder/Demultiplexer
- Circuit:
- 1 x 2:4
- Independent Circuits:
- 2
- Current - Output High, Low:
- 8mA, 8mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SO
SN74AHCT139NSR FAQ
1.How can I place an order for SN74AHCT139NSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHCT139NSR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for SN74AHCT139NSR reliable?
The price and inventory of SN74AHCT139NSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHCT139NSR is usually 5 days.
3.What payment methods are accepted for SN74AHCT139NSR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHCT139NSR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AHCT139NSR?
SN74AHCT139NSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHCT139NSR order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for SN74AHCT139NSR?
For technical support, including SN74AHCT139NSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHCT139NSR requirements.
6.How does Aetrix verify that SN74AHCT139NSR is sourced from the original manufacturer or authorized distributors?
All SN74AHCT139NSR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SN74AHCT139NSR meets industry standards.
7.What is the process for return or replacement of SN74AHCT139NSR?
All SN74AHCT139NSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHCT139NSR, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The SN74AHCT139NSR part is unused and in its original packaging.
Return procedure for SN74AHCT139NSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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