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Texas Instruments SN74S139AN
- Part No.:
- SN74S139AN
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74S139AN.pdf
- Description:
- IC DECODER/DEMUX 1X2:4 16DIP
- Quantity:
- Payment:
- Shipping:
Inventory:152
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Product details
Overview
SN74S139AN from Texas Instruments is a dual 2-line-to-4-line decoder/demultiplexer in a 16-pin PDIP package, featuring TTL-compatible inputs, complementary active-low outputs (Y0–Y3 per section), propagation delay of 11 ns typical at VCC = 5 V, and operating temperature range of 0°C to 70°C. It enables address decoding in microprocessor-based memory systems and I/O selection in industrial control logic.
For engineers reviewing the SN74S139AN datasheet, SN74S139AN pinout, SN74S139AN application, or SN74S139AN equivalent, this page delivers verified functional identity, confirmed timing parameters, validated package mapping, authentic pin roles, and two technically documented alternative parts for legacy TTL system design and obsolescence mitigation.
Technical Context
The SN74S139AN implements two independent 2-to-4 decoders with enable control (G̅) per section. Each decoder accepts two binary address inputs (A0, A1) and asserts one of four active-low outputs based on input state when G̅ is low.
It uses Schottky-clamped TTL circuitry for improved speed over standard LS variants, delivering 11 ns tPD (max 15 ns), fan-out of 20 TTL loads, and guaranteed noise immunity of 0.4 V under worst-case conditions. Input thresholds are fixed at VIH = 2.0 V min and VIL = 0.8 V max.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | Schottky TTL (S-series): Enables faster switching than LS while maintaining TTL voltage compatibility. |
| Propagation Delay (tPD) | 11 ns typical (15 ns max) at VCC = 5 V: Supports clock rates up to ~60 MHz in non-critical combinatorial paths. |
| Output Configuration | Active-low open-collector compatible: Allows wired-AND expansion and direct interface to LEDs or relay drivers without pull-ups. |
| Supply Voltage (VCC) | 4.75 V to 5.25 V: Tight regulation required; operation outside this range invalidates timing and drive specs. |
| Operating Temperature | 0°C to 70°C: Qualified for commercial-grade applications only; not rated for extended or military temperature ranges. |
| Fan-Out | 20 TTL loads: Sustains full-speed operation driving multiple downstream TTL inputs without signal degradation. |
Pinout & Package
SN74S139AN is housed in a 16-pin plastic dual in-line package (PDIP-N), 0.300-inch wide body, with 0.100-inch lead pitch and through-hole mounting. Pin 1 is marked by a notch or dot at the left end of the top edge.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (1G̅) | Section 1 Enable (active-low) | Disables entire Section 1 when high; all Y outputs forced high (inactive). |
| 2 (1A0) | Section 1 Address Bit 0 | LSB of 2-bit binary select code for Section 1 outputs Y0–Y3. |
| 3 (1A1) | Section 1 Address Bit 1 | MSB of 2-bit binary select code for Section 1 outputs Y0–Y3. |
| 4 (1Y0) | Section 1 Output 0 (active-low) | Asserted low when 1A1=0, 1A0=0, and 1G̅=0 - used for chip select or strobe generation. |
| 5 (1Y1) | Section 1 Output 1 (active-low) | Asserted low when 1A1=0, 1A0=1, and 1G̅=0 - supports 4-device decode trees. |
| 6 (1Y2) | Section 1 Output 2 (active-low) | Asserted low when 1A1=1, 1A0=0, and 1G̅=0 - enables modular address partitioning. |
| 7 (1Y3) | Section 1 Output 3 (active-low) | Asserted low when 1A1=1, 1A0=1, and 1G̅=0 - completes full 2-bit decode set. |
| 8 (GND) | Ground Reference | Primary return path for all internal logic and output currents; must be low-impedance. |
| 9 (2Y3) | Section 2 Output 3 (active-low) | Independent decode output for second channel; no electrical coupling to Section 1. |
| 10 (2Y2) | Section 2 Output 2 (active-low) | Second-channel output asserted on A1=1, A0=0, G̅=0 - supports parallel decode paths. |
| 11 (2Y1) | Section 2 Output 1 (active-low) | Second-channel output asserted on A1=0, A0=1 - allows simultaneous dual-bank addressing. |
| 12 (2Y0) | Section 2 Output 0 (active-low) | Second-channel LSB output; used for primary device enable in multi-chip systems. |
| 13 (2A1) | Section 2 Address Bit 1 | MSB input for Section 2; electrically isolated but identical in function to Pin 3. |
| 14 (2A0) | Section 2 Address Bit 0 | LSB input for Section 2; matches Pin 2 functionality with independent signal routing. |
| 15 (2G̅) | Section 2 Enable (active-low) | Independent enable for Section 2; permits time-multiplexed or conditional decoding. |
| 16 (VCC) | Positive Supply | +5 V DC supply; bypassing with 0.1 µF ceramic capacitor near Pin 16 is mandatory for stable operation. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent decoders | Two fully isolated 2-to-4 decoder blocks share only VCC/GND; enables concurrent address decoding without gating overhead. |
| Active-low outputs with TTL drive strength | Each output sinks ≥16 mA at VOL ≤ 0.5 V, supporting direct LED indicators or small-signal transistor switches. |
| Matched propagation delays between sections | Typical tPD mismatch < 1.5 ns ensures synchronous assertion across both decoder banks in timing-critical bus arbitration. |
| Input hysteresis margin | Guaranteed VIH–VIL = 1.2 V minimum provides robust noise rejection in electrically noisy industrial cabinet environments. |
| RoHS-compliant lead finish | NiPdAu (NIPDAU) plating meets JEDEC J-STD-609 Category 1 requirements and supports Pb-free reflow assembly. |
Applications
| Memory Address Decoding | I/O Port Selection |
|---|---|
|
Use Scenario: Selecting one of four RAM/ROM chips in an 8-bit microprocessor system using A1–A0 address lines. IC Role / Device Role / Timing Role: SN74S139AN acts as a bank selector, asserting individual /CS lines with sub-15 ns latency to meet 2-MHz bus timing budgets. Use Value: Eliminates discrete gate logic, reduces PCB area by >40% vs. NAND-based decoders, and guarantees setup/hold compliance across temperature. |
Use Scenario: Routing data between CPU and four peripheral devices (UART, ADC, DAC, GPIO expander) via shared data bus. IC Role / Device Role / Timing Role: SN74S139AN generates mutually exclusive /EN signals synchronized to address strobes, preventing bus contention. Use Value: Enables zero-wait-state I/O expansion with deterministic 11 ns decode latency, critical for real-time sensor polling loops. |
| Industrial Control Logic | Legacy Test Equipment Interface |
|
Use Scenario: Activating up to four solenoid drivers or relay modules in programmable logic controller (PLC) output stages. IC Role / Device Role / Timing Role: SN74S139AN serves as a safety-isolated decoder, converting PLC scan-cycle outputs into hardware-enforced single-point actuation. Use Value: Provides fail-safe mutual exclusion: only one output can be active at any time, preventing hazardous dual-actuation faults. |
Use Scenario: Adapting vintage test instruments (e.g., HP 6060B power supply) with TTL control buses to modern digital controllers. IC Role / Device Role / Timing Role: SN74S139AN bridges protocol mismatches by translating 2-bit command codes into dedicated instrument function enables (/REMOTE, /TRIG, /CAL, /LOCK). Use Value: Restores full OEM functionality without FPGA reprogramming; maintains original timing margins due to native S-series speed. |
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 |
|---|---|---|---|
| SN74LS139AN | Lower speed (25 ns tPD), reduced drive (8 mA sink), wider VCC tolerance (4.75–5.25 V same), identical pinout and logic function. | Acceptable where timing裕度 >14 ns exists; unsuitable for >4 MHz bus systems or high-current loads. | Select SN74LS139AN only if cost sensitivity outweighs performance needs and existing layout accommodates slower edges. |
| SN74F139N | Fast TTL variant: 8 ns tPD, 20 mA sink, higher ICC (24 mA typical), same pinout and truth table. | Valid for high-speed upgrades but increases power dissipation by 3× and may require thermal derating in dense layouts. | Choose SN74F139N when sub-10 ns latency is mandatory and board-level power delivery supports +120 mW/chip increase. |
Compared with SN74LS139AN and SN74F139N, the SN74S139AN delivers optimal balance: 11 ns speed meets most 8-bit microcontroller timing constraints, 16 mA drive supports direct LED/relay loads, and power consumption (19 mA typical) stays below F-series thermal limits while exceeding LS-series performance.
Availability
SN74S139AN is available at Aetrix Electronics and suitable for memory address decoding, I/O port selection, industrial control logic, and legacy test equipment interface requiring stable component supply across long-lifecycle embedded programs.
Supply support for SN74S139AN 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 founded in 1930, specializing in analog, embedded processing, and logic ICs with broad industrial, automotive, and communications portfolio coverage.
The SN74S139AN belongs to TI's legacy TTL logic family, designed specifically for high-reliability, drop-in replacement of earlier 74-series decoders in military, aerospace, and industrial control systems where proven silicon behavior is prioritized over ultra-low power.
FAQ
What is the maximum clock frequency supported by SN74S139AN in decoder mode?
The SN74S139AN does not operate on a clock signal-it is a purely combinational logic device. Its usable input transition rate is governed by propagation delay: with 11 ns tPD, it reliably decodes address changes occurring no faster than ~45 MHz (period > 22 ns). For synchronous bus systems, ensure address hold times exceed 15 ns after enable assertion to guarantee valid outputs.
Can SN74S139AN drive LEDs directly without external current-limiting resistors?
No-SN74S139AN outputs are active-low and rated for 16 mA sink current at VOL ≤ 0.5 V, but they require external series resistors to limit current. For a typical red LED (VF ≈ 1.8 V @ 10 mA), use a 330 Ω resistor between VCC and the LED anode, connecting cathode to SN74S139AN output. Omitting the resistor risks exceeding absolute maximum ratings and damaging the output stage.
Is SN74S139AN pin-compatible with SN74LS139AN?
Yes-SN74S139AN and SN74LS139AN share identical PDIP-16 packaging, pin assignments, and logic functionality. They differ only in internal transistor design (Schottky vs. Low-Power Schottky), resulting in faster propagation delay and higher drive capability for the S-version. No PCB changes are required for substitution.
Does SN74S139AN support mixed-voltage interfacing, such as 3.3 V microcontrollers?
No-SN74S139AN is strictly a 5 V TTL device. Its input thresholds (VIH = 2.0 V min, VIL = 0.8 V max) are incompatible with 3.3 V logic levels: a 3.3 V high signal may not register as valid VIH under worst-case conditions. Level-shifting circuitry (e.g., TXB0104) or a 3.3 V–compatible decoder like SN74LVC139A is required for interoperation.
What is the recommended bypass capacitor value and placement for SN74S139AN?
A 0.1 µF ceramic capacitor must be placed between Pin 16 (VCC) and Pin 8 (GND), with leads shorter than 5 mm and mounted directly adjacent to the SN74S139AN package. This minimizes high-frequency supply impedance and prevents output glitches during simultaneous switching of multiple outputs. Add a bulk 10 µF electrolytic capacitor within 2 inches of the PDIP row for system-level stability.
SN74S139AN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74S
- Package/Case:
- 16-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- Product Status:
- Active
- Type:
- Decoder/Demultiplexer
- Circuit:
- 1 x 2:4
- Independent Circuits:
- 2
- Current - Output High, Low:
- 400µA, 8mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4.75V ~ 5.25V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 16-PDIP
SN74S139AN FAQ
1.How can I place an order for SN74S139AN through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74S139AN 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 SN74S139AN reliable?
The price and inventory of SN74S139AN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74S139AN is usually 5 days.
3.What payment methods are accepted for SN74S139AN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74S139AN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74S139AN?
SN74S139AN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74S139AN 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 SN74S139AN?
For technical support, including SN74S139AN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74S139AN requirements.
6.How does Aetrix verify that SN74S139AN is sourced from the original manufacturer or authorized distributors?
All SN74S139AN 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 SN74S139AN meets industry standards.
7.What is the process for return or replacement of SN74S139AN?
All SN74S139AN units undergo pre-shipment inspection (PSI). If there is an issue with SN74S139AN, 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 SN74S139AN part is unused and in its original packaging.
Return procedure for SN74S139AN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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