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Texas Instruments CD74ACT138E
- Part No.:
- CD74ACT138E
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-DIP (0.300", 7.62mm)
- Datasheet:
-
CD74ACT138E.pdf
- Description:
- IC DECODER/DEMUX 1X3:8 16DIP
- Quantity:
- Payment:
- Shipping:
Inventory:783
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Product details
Overview
CD74ACT138E from Texas Instruments is a 3-line to 8-line decoder/demultiplexer in a 16-pin PDIP package, designed for high-speed memory decoding and data-routing applications. It features three enable inputs (G1 active-high, G2A/G2B active-low), ±24mA output drive, 3.1–10.9ns propagation delay at 5V/85°C, and TTL-voltage-compatible inputs for seamless interface with legacy logic families.
For engineers reviewing the CD74ACT138E datasheet, CD74ACT138E pinout, CD74ACT138E application, or CD74ACT138E equivalent, this device serves as a low-power, high-speed address decoder in industrial control systems, FPGA I/O expansion, and embedded memory subsystems where precise 3-bit binary selection and cascading capability are required.
Technical Context
The CD74ACT138E implements positive-logic decoding with active-low outputs (Y0–Y7) and three independent enable controls that support hierarchical expansion-e.g., enabling 24-line decoding without external inverters. Its CMOS ACT technology delivers bipolar F/AS/S speed grades with significantly reduced power versus comparable bipolar devices.
Propagation delays are balanced across all input-to-output paths (tPLH/tPHL ≤ 10.9ns over –40°C to +85°C), and the device operates within a strict 4.5V–5.5V supply range while maintaining TTL-compatible VIH/VIL thresholds (2.0V/0.8V) and ±24mA drive capability into standard loads.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5V to 5.5V - ensures compatibility with standard 5V logic rails and stable operation under rail tolerance variations |
| Propagation Delay | 3.1ns to 10.9ns - enables sub-10ns address decoding critical for high-speed SRAM and EPROM access timing |
| Output Drive | ±24mA - supports fanout to 15 F-series logic devices or direct driving of small-signal loads without buffers |
| Input Compatibility | TTL-voltage - accepts standard 0.8V/2.0V logic thresholds, eliminating level-shifting in mixed-technology systems |
| Operating Temp | –55°C to +125°C - qualified for extended industrial and military-grade environments per CD74ACT138E's production status |
| ESD Rating | ±2000V HBM - exceeds MIL-STD-883 requirement, reducing susceptibility to handling damage in manufacturing |
| Power Dissipation Cap | 110pF Cpd - quantifies dynamic switching energy, enabling accurate power budgeting in dense logic arrays |
Pinout & Package
CD74ACT138E uses a 16-pin plastic dual in-line package (PDIP-N), body size 19.3mm × 6.35mm, with through-hole mounting and industry-standard 0.3" wide DIP footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A, B, C | Binary select inputs | 3-bit address lines determining which of eight outputs (Y0–Y7) is asserted low |
| G1 | Active-high enable | Primary global enable; device disabled when low, regardless of G2A/G2B state |
| G2A, G2B | Active-low enables | Secondary enables allowing cascaded decoding schemes without external inverters |
| Y0–Y7 | Active-low decoded outputs | Only one output goes low per valid input combination; all others remain high |
| VCC | Positive supply | 5V nominal supply pin requiring local 0.1μF bypass capacitor per TI layout guidelines |
| GND | Ground reference | Common return path for all internal logic and output current sinks |
Key Features
| Feature | Design Value |
|---|---|
| Three enable inputs | Enables flexible cascading: e.g., 24-line decoding with zero external inverters, 32-line with one inverter |
| SCR-latchup-resistant process | Guarantees immunity to latch-up under transient overvoltage or ESD events in real-world PCB environments |
| Balanced propagation delays | Ensures deterministic timing across all decode paths-critical for synchronous memory enable sequencing |
| ±24mA output drive | Directly interfaces with multiple F-series logic inputs or drives small LEDs/relays without external buffers |
| TTL-compatible inputs | Eliminates need for level translators when interfacing with 74LS, 74F, or microcontroller GPIOs |
Applications
| Memory Address Decoding | FPGA I/O Expansion |
|---|---|
Use Scenario: Selecting one of eight SRAM or Flash memory chips in a banked architecture using 3-bit address bus. IC Role / Device Role / Timing Role: High-speed address decoder asserting chip-select (CS#) signals with <11ns delay to meet tight memory access windows. Use Value: Minimizes system decoding overhead-effective delay negligible versus typical 55ns SRAM access time. | Use Scenario: Expanding limited FPGA GPIO count to drive discrete peripherals (ADCs, DACs, sensors) via 3-bit address mapping. IC Role / Device Role / Timing Role: Demultiplexer routing control signals from shared bus lines to individual peripheral enable inputs. Use Value: Reduces FPGA pin utilization by 5:1 while preserving deterministic, low-jitter signal routing. |
| Industrial Control Logic | Legacy System Interface |
Use Scenario: Enabling specific PLC I/O modules in a modular backplane based on configuration register bits. IC Role / Device Role / Timing Role: Cascadable decoder providing eight independent module-enable signals with simultaneous enable coordination. Use Value: Enables hot-swappable module detection and selective power gating without software intervention. | Use Scenario: Interfacing modern microcontrollers with vintage TTL-based instrumentation (e.g., test equipment front panels). IC Role / Device Role / Timing Role: Level- and timing-transparent bridge between CMOS MCU outputs and TTL input thresholds. Use Value: Preserves original system timing margins while eliminating discrete resistor networks for voltage translation. |
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 |
|---|---|---|---|
| SN74ACT138N | Identical electrical specs and pinout; same PDIP-16 package but manufactured by TI under commercial catalog branding | No functional difference; SN74ACT138N shares identical AC/DC characteristics and thermal ratings | Select CD74ACT138E for extended temperature qualification (–55°C to +125°C); SN74ACT138N rated –40°C to +85°C |
| 74HC138N | Lower drive (±4mA), slower max speed (24ns), no TTL input compatibility, 2V–6V supply range | Suitable only in new designs with pure CMOS signaling and relaxed timing; cannot replace CD74ACT138E in TTL-interfaced systems | Choose only if cost sensitivity outweighs speed, drive, and interface requirements-and full revalidation is feasible |
Compared with SN74ACT138N, CD74ACT138E offers guaranteed operation at –55°C and +125°C, making it suitable for aerospace and extended-industrial deployments; versus 74HC138N, CD74ACT138E provides 6× higher output drive and sub-11ns timing essential for legacy system interoperability.
Availability
CD74ACT138E is available at Aetrix Electronics and suitable for industrial control systems, legacy instrumentation upgrades, and high-reliability memory subsystems requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for CD74ACT138E 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 high-reliability components.
The CD74ACT138E belongs to TI's Advanced CMOS (ACT) logic family, engineered for high-speed memory decoding and data-routing applications demanding TTL compatibility, low power, and robust industrial temperature performance.
FAQ
What is the maximum operating temperature for CD74ACT138E?
The CD74ACT138E is fully specified and tested over an operating free-air temperature range of –55°C to +125°C, meeting extended industrial and military-grade environmental requirements. This rating is confirmed in Section 4.3 (Recommended Operating Conditions) of the official TI datasheet SCHS329C, and applies specifically to the CD74ACT138E PDIP variant-not just the broader ACT138 family.
Does CD74ACT138E support cascading for larger decoder configurations?
Yes, CD74ACT138E supports seamless cascading via its three enable inputs (G1, G2A, G2B): two active-low (G2A/G2B) and one active-high (G1). As documented in Section 6.3 and Figure 7-1, this allows implementation of 24-line decoding without external inverters and 32-line decoding with only one inverter-enabling scalable address expansion in memory and I/O systems.
What is the output drive capability of CD74ACT138E?
CD74ACT138E provides ±24mA output drive current per pin, verified across the full operating temperature range (–55°C to +125°C). This is explicitly stated in Section 1 Features and Table 4.3, enabling direct fanout to 15 F-series logic devices or driving moderate loads such as LEDs or small-signal transistors without buffering.
Is CD74ACT138E compatible with TTL-level input signals?
Yes, CD74ACT138E features TTL-voltage-compatible inputs, with guaranteed VIH = 2.0V min and VIL = 0.8V max across temperature and supply voltage (Section 4.3). This allows direct connection to 74LS, 74F, and other TTL-family outputs without level-shifting circuitry-confirmed in both the Features list and Electrical Characteristics table.
What package type does CD74ACT138E use?
CD74ACT138E uses a 16-pin plastic dual in-line package (PDIP-N), with body dimensions of 19.3mm × 6.35mm and standard 0.3" width. This is clearly identified in the PACKAGE OPTION ADDENDUM and Mechanical section of the TI datasheet SCHS329C, and distinguishes it from WQFN (BQB), SOIC (D), and TSSOP (PW) variants of the same logic function.
CD74ACT138E Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ACT
- 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:
- 24mA, 24mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -55°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 16-PDIP
CD74ACT138E FAQ
1.How can I place an order for CD74ACT138E through Aetrix?
Please submit a Request for Quotation (RFQ) for CD74ACT138E 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 CD74ACT138E reliable?
The price and inventory of CD74ACT138E are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD74ACT138E is usually 5 days.
3.What payment methods are accepted for CD74ACT138E?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD74ACT138E transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD74ACT138E?
CD74ACT138E orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD74ACT138E 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 CD74ACT138E?
For technical support, including CD74ACT138E datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD74ACT138E requirements.
6.How does Aetrix verify that CD74ACT138E is sourced from the original manufacturer or authorized distributors?
All CD74ACT138E 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 CD74ACT138E meets industry standards.
7.What is the process for return or replacement of CD74ACT138E?
All CD74ACT138E units undergo pre-shipment inspection (PSI). If there is an issue with CD74ACT138E, 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 CD74ACT138E part is unused and in its original packaging.
Return procedure for CD74ACT138E:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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