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Texas Instruments SN74HCT139DT
- Part No.:
- SN74HCT139DT
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74HCT139DT.pdf
- Description:
- IC DECODER/DEMUX 1X2:4 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,543
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Product details
Overview
SN74HCT139DT from Texas Instruments is a dual 2-line-to-4-line decoder/demultiplexer in SOIC-16 package, operating at 4.5–5.5 V, with 10 ns typical propagation delay, ±4-mA output drive, and TTL-compatible inputs. It serves as a high-speed memory address decoder in microcontroller-based embedded systems requiring precise enable-controlled signal routing.
For engineers reviewing the SN74HCT139DT datasheet, SN74HCT139DT pinout, SN74HCT139DT application, or SN74HCT139DT equivalent, this page delivers verified functional modes, real-world timing behavior under 50-pF load, supply-current stability across temperature, and validated alternatives for memory decode and data-path demuxing in industrial control and instrumentation designs.
Technical Context
The SN74HCT139DT integrates two independent decoders, each with active-low enable (G) and dual select inputs (A, B), supporting cascaded decoding via shared or separate enables. Its fully buffered inputs present only one normalized LSTTL load, minimizing fanout burden on upstream logic.
Propagation delay is specified at 12–51 ns (VCC = 4.5–5.5 V, CL = 50 pF), with output drive capability of ±4 mA at 5 V and low ICC of ≤80 µA - enabling use in power-constrained, high-density PCB layouts where timing predictability and static current matter.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - ensures compatibility with standard 5-V TTL/CMOS logic rails and stable operation across industrial voltage tolerances. |
| Propagation Delay (tpd) | 12 ns (min) to 40 ns (max) at 5.5 V, CL = 50 pF - enables sub-25-MHz synchronous decode timing in memory subsystems. |
| Output Drive | ±4 mA at 5 V - sufficient to directly drive 10 LSTTL loads without external buffers, reducing component count in address decoding trees. |
| Input Compatibility | TTL-voltage compatible (VIH = 2 V, VIL = 0.8 V) - allows seamless interfacing with legacy 74LS and microcontroller GPIO without level-shifting. |
| Quiescent Current (ICC) | ≤80 µA max at 5.5 V - supports low-static-power system design, critical for always-on control logic and battery-backed modules. |
| Operating Temperature | −40°C to +85°C - qualified for industrial-grade operation in programmable logic controllers, motor drives, and test equipment. |
Pinout & Package
SN74HCT139DT is housed in a 16-pin SOIC (D) package measuring 9.90 mm × 3.90 mm, with 1.27-mm pitch, RoHS-compliant NiPdAu lead finish, and MSL Level-1 rating for unlimited reflow.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 15, 16 | G1, G2, VCC | Active-low enable inputs (G1/G2) allow independent or synchronized activation of each decoder; VCC powers both sections. |
| 2, 3, 4, 5 | A1, B1, Y10–Y13 | First decoder: A1/B1 select lines; Y10–Y13 are active-low decoded outputs (only one low per valid input combination). |
| 12, 13, 10, 9 | A2, B2, Y20–Y23 | Second decoder: A2/B2 select lines; Y20–Y23 are active-low outputs, electrically isolated but sharing VCC/GND. |
| 7, 8, 14 | GND, Y11, Y21 | GND reference for all logic; Y11/Y21 are dedicated output pins - no internal NC or analog functions. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent decoders | Enables compact implementation of two parallel 2:4 decode paths - e.g., one for memory chip select, another for peripheral I/O mapping - without inter-stage delay penalties. |
| Active-low enable with TTL compatibility | Allows direct connection to microcontroller active-low chip-select signals or open-collector bus drivers without pull-up resistors or inverters. |
| Low input current (≤1 µA) | Minimizes loading on upstream drivers - critical when driving multiple SN74HCT139DT units from a single FPGA I/O bank or microcontroller port. |
| High noise immunity | Guaranteed VIH ≥ 2 V and VIL ≤ 0.8 V at 5 V supply provides >0.4 V noise margin against EMI in industrial environments. |
| Thermal robustness | RθJA = 73°C/W (SOIC) ensures junction temperature stays within safe limits (<125°C) even at full 85°C ambient with moderate power dissipation. |
Applications
| Memory Address Decoding | Peripheral Select Logic |
|---|---|
|
Use Scenario: Decoding 2-bit address bus to select among four SRAM chips in an 8-bit microcontroller system. IC Role / Device Role / Timing Role: SN74HCT139DT acts as a synchronous address decoder, asserting individual /CS lines with <40 ns delay to meet SRAM access setup requirements. Use Value: Eliminates need for discrete NAND gates or CPLD-based decode logic, reducing BOM cost and layout area while maintaining deterministic timing. |
Use Scenario: Routing UART, SPI, and I²C peripherals to a shared MCU bus using hardware-selectable addressing. IC Role / Device Role / Timing Role: SN74HCT139DT provides mutually exclusive enable signals to isolate peripheral transceivers during communication bursts. Use Value: Prevents bus contention and signal corruption by ensuring only one peripheral responds per transaction, with zero-latency enable assertion. |
| Industrial I/O Expansion | Test Equipment Signal Routing |
|
Use Scenario: Expanding digital output capability of a PLC CPU module to drive 8 discrete solenoid valves via two SN74HCT139DT units. IC Role / Device Role / Timing Role: SN74HCT139DT translates 2-bit command codes into 4-channel valve enable patterns, synchronized to PLC scan cycle. Use Value: Delivers deterministic, glitch-free valve actuation with <10 ns skew between channels - essential for coordinated motion control sequences. |
Use Scenario: Configuring signal paths in automated test equipment to route DUT signals to measurement instruments based on test step. IC Role / Device Role / Timing Role: SN74HCT139DT functions as a demultiplexer, steering stimulus signals from a single source to one of four DUT pins. Use Value: Enables fast, repeatable channel switching (<50 ns settling) without relay wear or analog multiplexer nonlinearity, improving test throughput and accuracy. |
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 |
|---|---|---|---|
| 74HC139DR | Higher VCC range (2–6 V), slower tpd (27 ns typ), lower drive (±4 mA at 6 V only), CMOS-input thresholds. | Preferred for mixed-voltage systems (3.3 V/5 V) but requires level adaptation if driven by pure TTL sources. | Select when wider supply flexibility outweighs need for strict TTL compatibility and minimal propagation delay. |
| SN74LS139N | Bipolar TTL process: higher ICC (19 mA), faster tpd (15 ns typ), lower noise margin, incompatible with CMOS inputs. | Suitable only in legacy 5-V TTL-only systems; cannot interface directly with modern microcontrollers or CMOS logic. | Choose only for backward compatibility in existing LS-based designs - not recommended for new industrial or embedded projects. |
Compared with SN74HCT139DT, 74HC139DR offers broader voltage operation but sacrifices TTL-level input compatibility and worst-case speed; SN74LS139N delivers raw speed and drive strength but demands higher power and lacks CMOS-friendly inputs - making SN74HCT139DT the optimal balance for modern 5-V embedded decode tasks.
Availability
SN74HCT139DT is available at Aetrix Electronics and suitable for industrial control panels, test instrumentation, and microcontroller-based memory expansion systems requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.
Supply support for SN74HCT139DT 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 90 years of innovation in industrial, automotive, and communications markets.
The SN74HCT139DT belongs to TI's HCT logic family - engineered for TTL-compatible operation at CMOS power levels, targeting high-reliability memory decoding and data-routing applications in harsh environments.
FAQ
What is the maximum clock frequency supported by SN74HCT139DT in demultiplexer mode?
The SN74HCT139DT does not operate on a clock signal - it is combinational logic. Its effective maximum switching rate is determined by propagation delay and load capacitance. With CL = 50 pF and VCC = 5.5 V, the worst-case tpd is 40 ns, supporting reliable operation up to ~12 MHz toggle rate in demux applications, assuming clean input edges and proper termination.
Can SN74HCT139DT drive LEDs directly without current-limiting resistors?
No. While SN74HCT139DT provides ±4 mA output drive at 5 V, its VOL rises to 0.33 V at 4 mA - insufficient to guarantee LED turn-on or consistent brightness. Direct LED driving risks exceeding absolute max output current (±25 mA) and violates recommended operating conditions. Always use series resistors to limit current to ≤4 mA per output.
Is SN74HCT139DT pin-compatible with SN74HCT138N?
No. SN74HCT139DT is a dual 2-to-4 decoder in 16-pin SOIC; SN74HCT138N is a single 3-to-8 decoder in 16-pin PDIP. They differ in pin function mapping, number of select inputs (2 vs. 3), output count (4×2 vs. 8), and enable architecture (two active-low G inputs vs. three enables). PCB redesign is required for substitution.
Does SN74HCT139DT require external pull-up resistors on its outputs?
No. SN74HCT139DT features totem-pole outputs capable of actively driving both high and low states. Pull-ups are unnecessary unless interfacing with open-drain systems or implementing wired-OR logic - which is not supported by this device's output structure.
What is the thermal resistance (RθJA) of SN74HCT139DT in its SOIC package?
The SN74HCT139DT in SOIC (D) package has a published RθJA of 73°C/W. This value assumes JEDEC-standard 2-layer board layout with 1-in² copper pour. Actual thermal performance may vary with PCB stack-up, copper area, and airflow - derate power dissipation accordingly for operation above 60°C ambient.
SN74HCT139DT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HCT
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Decoder/Demultiplexer
- Circuit:
- 1 x 2:4
- Independent Circuits:
- 2
- Current - Output High, Low:
- 4mA, 4mA
- 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-SOIC
SN74HCT139DT FAQ
1.How can I place an order for SN74HCT139DT through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HCT139DT 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 SN74HCT139DT reliable?
The price and inventory of SN74HCT139DT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HCT139DT is usually 5 days.
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SN74HCT139DT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HCT139DT 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 SN74HCT139DT?
For technical support, including SN74HCT139DT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HCT139DT requirements.
6.How does Aetrix verify that SN74HCT139DT is sourced from the original manufacturer or authorized distributors?
All SN74HCT139DT 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 SN74HCT139DT meets industry standards.
7.What is the process for return or replacement of SN74HCT139DT?
All SN74HCT139DT units undergo pre-shipment inspection (PSI). If there is an issue with SN74HCT139DT, 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 SN74HCT139DT part is unused and in its original packaging.
Return procedure for SN74HCT139DT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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