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Texas Instruments SN74HC138NE4
- Part No.:
- SN74HC138NE4
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74HC138NE4.pdf
- Description:
- 3-LINE TO 8-LINE DECODERS/DEMULT
- Quantity:
- Payment:
- Shipping:
Inventory:3,772
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Product details
Overview
SN74HC138NE4 from Texas Instruments is a 3-line to 8-line decoder/demultiplexer in PDIP-16 package, operating from 2 V to 6 V, with typical propagation delay of 15 ns at 6 V, ±4-mA output drive at 5 V, and active-low outputs enabling direct LED column sinking in matrix displays.
For engineers reviewing the SN74HC138NE4 datasheet, SN74HC138NE4 pinout, SN74HC138NE4 application, or SN74HC138NE4 equivalent, this device serves as a high-speed memory decoder, address demultiplexer, or low-side LED driver where precise 3-bit binary selection and cascading enable control are required.
Technical Context
The SN74HC138NE4 implements a CMOS-based 3-to-8 decoding function with three binary select inputs (A, B, C), one active-high enable (G1), and two active-low enables (G2A, G2B). All enables must be asserted for any output to activate - ensuring robust cascading without external logic inversion.
Its active-low outputs (Y0–Y7) sink current when selected, supporting direct interface with common-anode LED arrays or high-impedance bus systems. Propagation delay remains under 38 ns across the full 2–6 V supply range and –40°C to +85°C operating temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 2 V to 6 V - supports mixed-voltage system interfacing and legacy 5-V TTL compatibility. |
| Propagation Delay (tpd) | 15 ns (typ) at VCC = 6 V - enables use in high-speed memory decode paths with negligible system delay penalty. |
| Output Drive | ±4 mA at 5 V - sufficient to directly drive LSTTL loads or sink LED columns without external transistors. |
| Input Current | ≤1 µA max - ensures minimal loading on upstream logic and stable operation with high-impedance control sources. |
| Quiescent Current (ICC) | 80 µA max at VCC = 6 V - supports low-power standby modes in battery-backed or energy-conscious designs. |
| Operating Temperature | –40°C to +85°C - qualified for industrial-grade embedded applications including building and factory automation. |
Pinout & Package
SN74HC138NE4 uses a 16-pin PDIP (Plastic Dual In-line Package) with 19.32 mm × 6.35 mm body size and through-hole mounting. Pin numbering follows standard DIP orientation (pin 1 in top-left corner, notch or dot marking pin 1).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (A) | Select input A (LSB) | Binary address bit 0; determines least-significant output selection when all enables are active. |
| 2 (B) | Select input B | Binary address bit 1; combined with A and C to uniquely select one of eight outputs. |
| 3 (C) | Select input C (MSB) | Binary address bit 2; MSB of 3-bit address used for full 8-output decoding. |
| 4 (G2A) | Active-low enable A | First enable input; must be LOW for decoder operation - simplifies hierarchical expansion with shared enable trees. |
| 5 (G2B) | Active-low enable B | Second active-low enable; both G2A and G2B must be LOW alongside G1 HIGH for functional output. |
| 6 (G1) | Active-high enable | Primary enable; must be HIGH to activate decoding - allows use as data input in demultiplexing mode. |
| 7 (Y7) | Output Y7 (MSB) | Active-low decoded output corresponding to A=1, B=1, C=1 - sinks current when selected. |
| 8 (GND) | Ground reference | Power return path; must be connected to system ground plane for stable logic thresholds and noise immunity. |
| 9 (Y6) | Output Y6 | Active-low output for A=1, B=1, C=0 - provides discrete channel selection in 8-channel routing. |
| 10 (Y5) | Output Y5 | Active-low output for A=1, B=0, C=1 - used in address decoding for peripheral chip selects. |
| 11 (Y4) | Output Y4 | Active-low output for A=1, B=0, C=0 - enables selective activation of subsystems in modular architectures. |
| 12 (Y3) | Output Y3 | Active-low output for A=0, B=1, C=1 - supports multiplexed sensor or actuator addressing. |
| 13 (Y2) | Output Y2 | Active-low output for A=0, B=1, C=0 - commonly used in display column scanning with constant-current drivers. |
| 14 (Y1) | Output Y1 | Active-low output for A=0, B=0, C=1 - interfaces with interrupt controllers or status registers. |
| 15 (Y0) | Output Y0 (LSB) | Active-low output for A=0, B=0, C=0 - default channel for boot-time initialization or default I/O mapping. |
| 16 (VCC) | Positive supply | CMOS power rail; requires local 0.1-µF bypass capacitor to suppress switching noise and ensure timing stability. |
Key Features
| Feature | Design Value |
|---|---|
| Three enable inputs (G1, G2A, G2B) | Enables seamless 24-line decoding without external inverters and 32-line expansion with only one inverter. |
| Active-low outputs | Directly drives common-anode LED matrices or pulls down microcontroller input pins for interrupt generation. |
| Low input current (≤1 µA) | Minimizes loading on FPGA I/O banks or microcontroller GPIOs used as address/control lines. |
| Wide voltage operation (2–6 V) | Permits interoperability between 3.3-V logic controllers and 5-V legacy peripherals without level shifters. |
| High-speed propagation (15 ns typ @ 6 V) | Meets timing budgets in fast memory subsystems where decoder delay must be less than memory access time. |
Applications
| LED Matrix Display Control | Industrial Memory Address Decoding |
|---|---|
|
Use Scenario: Driving the column lines of an 8×8 common-anode LED matrix using row-scanning MCU GPIOs. IC Role / Device Role / Timing Role: Low-side column selector that activates exactly one Yx output per scan cycle while remaining outputs stay HIGH. Use Value: Eliminates need for discrete transistors or dedicated LED drivers; leverages built-in active-low outputs and 4-mA sink capability. |
Use Scenario: Generating chip-select signals for up to eight SRAM or flash memory devices in an embedded controller subsystem. IC Role / Device Role / Timing Role: High-speed address decoder translating upper address bits into individual memory enable lines. Use Value: Propagation delay ≤38 ns ensures no added wait states in memory read/write cycles at 25-MHz bus speeds. |
| Factory Automation I/O Expansion | Building Management System Peripheral Selection |
|
Use Scenario: Expanding digital output capability of a PLC controller to drive solenoids, relays, or indicator lamps across eight zones. IC Role / Device Role / Timing Role: Demultiplexer converting serial control commands into parallel zone-enable signals via G1 as data input. Use Value: Enables single-wire command distribution with hardware-level decoding - reducing wiring complexity and controller pin count. |
Use Scenario: Selecting HVAC sensors, lighting controllers, or door-lock modules in a centralized building automation panel. IC Role / Device Role / Timing Role: Address decoder receiving 3-bit module ID over RS-485 bus to assert dedicated enable line for targeted device. Use Value: Supports hot-swappable module identification and reduces firmware overhead by offloading address resolution to hardware. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 3-to-8 decoder applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 74HC238D | Identical pinout and logic function but features active-high outputs instead of active-low. | Requires external inverters or redesign of load interface when replacing SN74HC138NE4 in LED-sinking or open-collector configurations. | Select only if system design expects HIGH-active outputs and can accommodate inverted signal polarity. |
| SN74LS138N | Bipolar TTL version with higher ICC (≈30 mA), slower tpd (≈25 ns min), and narrower 4.75–5.25 V supply range. | Suitable for legacy 5-V TTL systems but incompatible with mixed-voltage or low-power designs due to higher current draw and noise sensitivity. | Choose only for drop-in replacement in existing LS-based boards where power and speed margins allow. |
Compared with 74HC238D and SN74LS138N, SN74HC138NE4 delivers optimal balance of low power (80 µA ICC), wide supply range (2–6 V), and active-low outputs ideal for direct LED and relay driving - making it the preferred choice for modern industrial and display applications requiring flexibility and efficiency.
Availability
SN74HC138NE4 is available at Aetrix Electronics and suitable for industrial automation, LED display systems, and embedded memory decoding requiring stable component supply and long-term manufacturability.
Supply support for SN74HC138NE4 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 experience delivering reliable, high-performance components for industrial and automotive markets.
The SN74HC138NE4 belongs to TI's HC logic family, designed specifically for high-speed, low-power memory decoding and data-routing applications where propagation delay, power efficiency, and cascading flexibility are critical.
FAQ
What is the maximum supply voltage rating for SN74HC138NE4?
The absolute maximum supply voltage for SN74HC138NE4 is 7 V, but the recommended operating range is 2 V to 6 V. Operation above 6 V risks exceeding electrical limits and may cause permanent damage or parametric degradation. Always observe the 6 V upper limit in normal use.
Does SN74HC138NE4 support cascading for larger decoding schemes?
Yes, SN74HC138NE4 supports cascading via its three enable inputs (G1, G2A, G2B). Two active-low enables and one active-high enable allow multiple devices to be connected without external inverters - enabling 24-line decoding natively and 32-line with just one inverter.
Can SN74HC138NE4 directly drive LEDs in a matrix configuration?
Yes, SN74HC138NE4 can directly drive common-anode LED columns. Its active-low outputs sink up to 4 mA at 5 V, matching typical LED segment current requirements. The device ensures only one output is LOW at a time, preventing ghosting or excessive current draw during scanning.
What is the operating temperature range of SN74HC138NE4?
SN74HC138NE4 is rated for operation from –40°C to +85°C, qualifying it for industrial environments including factory floors, building automation panels, and outdoor power infrastructure equipment where ambient temperatures vary widely.
Is SN74HC138NE4 pin-compatible with other 74HC138 variants?
Yes, SN74HC138NE4 shares identical pinout and functionality with all PDIP-packaged 74HC138 variants (e.g., SN74HC138N), including identical pin numbering, signal assignments, and electrical behavior - enabling direct substitution within the same package footprint.
SN74HC138NE4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HC
- Package/Case:
- 16-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- Decoder/Demultiplexer
- Circuit:
- 1 x 3:8
- Independent Circuits:
- 1
- Current - Output High, Low:
- 5.2mA, 5.2mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 2V ~ 6V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 16-PDIP
SN74HC138NE4 FAQ
1.How can I place an order for SN74HC138NE4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HC138NE4 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 SN74HC138NE4 reliable?
The price and inventory of SN74HC138NE4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HC138NE4 is usually 5 days.
3.What payment methods are accepted for SN74HC138NE4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HC138NE4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HC138NE4?
SN74HC138NE4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HC138NE4 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 SN74HC138NE4?
For technical support, including SN74HC138NE4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HC138NE4 requirements.
6.How does Aetrix verify that SN74HC138NE4 is sourced from the original manufacturer or authorized distributors?
All SN74HC138NE4 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 SN74HC138NE4 meets industry standards.
7.What is the process for return or replacement of SN74HC138NE4?
All SN74HC138NE4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74HC138NE4, 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 SN74HC138NE4 part is unused and in its original packaging.
Return procedure for SN74HC138NE4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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