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Texas Instruments CD54AC138F3A
- Part No.:
- CD54AC138F3A
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-CDIP (0.300", 7.62mm)
- Datasheet:
-
CD54AC138F3A.pdf
- Description:
- CD54AC138 3-LINE TO 8-LINE INVER
- Quantity:
- Payment:
- Shipping:
Inventory:1,342
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Product details
Overview
CD54AC138F3A from Texas Instruments is a military-grade 3-line-to-8-line decoder/demultiplexer in a 16-pin CDIP package, operating from 1.5 V to 5.5 V with ±24-mA output drive, 2.8 ns typical propagation delay at 5 V, and SCR-latchup-resistant CMOS process. It serves as a high-speed memory decoder in aerospace avionics systems requiring MIL-PRF-38535 qualification.
For engineers reviewing the CD54AC138F3A datasheet, CD54AC138F3A pinout, CD54AC138F3A application, or CD54AC138F3A equivalent, key selection criteria include its triple-enable architecture (G1, G2A, G2B), balanced tPLH/tPHL timing, –55°C to 125°C operating range, and compatibility with cascaded 24- or 32-line decoding schemes without external inverters.
Technical Context
The CD54AC138F3A implements positive-logic decoding with three binary select inputs (A, B, C) and three enable terminals (G1 active-high; G2A, G2B active-low), enabling precise output line selection only when all enables are asserted. Its internal logic ensures simultaneous activation of exactly one of eight active-low outputs (Y0–Y7) per input combination.
Designed for high-speed memory systems, it features balanced propagation delays across all input-to-output paths (tPLH/tPHL ≤ 11 ns at VCC = 5 V, CL = 50 pF), low power consumption versus bipolar equivalents, and noise immunity at 30% of supply voltage-critical for deterministic timing in radiation-tolerant embedded control subsystems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 1.5 V to 5.5 V - supports mixed-voltage system integration and battery-backed operation |
| Propagation Delay (tPLH/tPHL) | 2.8 ns (typ) at 5 V - enables sub-10-ns system-level address decode in high-speed memory subsystems |
| Output Drive Current | ±24 mA - drives 15 F-series logic loads directly without buffering |
| Operating Temperature | –55°C to 125°C - qualified for extended-range military and aerospace environments |
| ESD Protection | >2 kV per MIL-STD-883 Method 3015 - ensures robustness in handling and board assembly |
| Input Thresholds | VIH = 3.85 V, VIL = 1.65 V at VCC = 5.5 V - provides 30% noise margin for reliable signal discrimination |
| Power Dissipation Capacitance | 110 pF - determines dynamic power consumption in high-frequency switching applications |
Pinout & Package
CD54AC138F3A uses a 16-pin Ceramic Dual In-line Package (CDIP) with hermetic sealing and lead finish compliant with MIL-PRF-38535 requirements. Package drawing J, 0.300-inch wide body, 0.100-inch lead pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (G2A) | Active-low enable input | Must be low to activate decoder; used with G2B and G1 for hierarchical enable control |
| 2 (G2B) | Active-low enable input | Second active-low enable; both G2A and G2B must be low for function enable |
| 3 (G1) | Active-high enable input | Must be high to activate decoder; simplifies cascading with minimal external logic |
| 4 (C) | MSB binary select input | Most significant bit of 3-bit address; determines Y4–Y7 vs Y0–Y3 group selection |
| 5 (B) | Binary select input | Mid-significance bit; combined with A and C to uniquely select one of eight outputs |
| 6 (A) | LSB binary select input | Least significant bit; completes 3-bit address decoding for output line selection |
| 7 (Y0) | Active-low decoded output | Asserted low when A=B=C=0 and all enables active; drives memory chip-select or peripheral enable |
| 8 (GND) | Ground reference | Primary return path for all internal logic and output currents; requires low-impedance PCB connection |
| 9 (Y1) | Active-low decoded output | Asserted low when A=1, B=C=0 and enables active; used for discrete peripheral addressing |
| 10 (Y2) | Active-low decoded output | Asserted low when B=1, A=C=0; supports modular I/O expansion in ruggedized controllers |
| 11 (Y3) | Active-low decoded output | Asserted low when A=B=1, C=0; enables selective activation of dual-function subsystems |
| 12 (Y4) | Active-low decoded output | Asserted low when C=1, A=B=0; routes control signals in multi-bank memory architectures |
| 13 (Y5) | Active-low decoded output | Asserted low when C=1, A=1, B=0; supports time-critical interrupt vectoring in real-time OS kernels |
| 14 (Y6) | Active-low decoded output | Asserted low when C=1, B=1, A=0; used for redundant sensor interface selection in flight control units |
| 15 (Y7) | Active-low decoded output | Asserted low when A=B=C=1; activates highest-priority subsystem or diagnostic mode |
| 16 (VCC) | Positive supply rail | Supplies core logic and output drivers; requires local 100-nF ceramic decoupling per MIL-HDBK-454 |
Key Features
| Feature | Design Value |
|---|---|
| Triple Enable Architecture | G1 (active-high), G2A/G2B (active-low) allow flexible cascading of up to four devices for 24-line decoding without external inverters |
| Balanced Propagation Delays | tPLH and tPHL match within 0.2 ns at 5 V - eliminates skew-induced timing hazards in synchronous memory interfaces |
| SCR-Latchup Resistance | CMOS process with guard rings prevents destructive latchup under transient overvoltage events common in avionics power rails |
| Wide-Voltage Operation | 1.5 V to 5.5 V supply range enables direct interfacing with 1.8-V, 3.3-V, and 5-V logic families in mixed-signal systems |
| MIL-PRF-38535 Qualification | F3A suffix denotes full QML Class V screening including burn-in, temperature cycling, and lot acceptance testing per military standards |
Applications
| Aerospace Avionics Memory Decoding | Defense System Interrupt Vectoring |
|---|---|
Use Scenario: Address decoding for triple-redundant SRAM banks in flight control computers where deterministic latency is mandated by DO-254 Level A. IC Role / Device Role / Timing Role: Primary 3-to-8 decoder asserting chip-select lines for memory modules with sub-10-ns worst-case propagation delay. Use Value: Enables memory access cycles to complete within 15 ns total budget, meeting ARINC 653 partition timing constraints. | Use Scenario: Prioritized interrupt routing in missile guidance processors requiring guaranteed response to hardware fault signals. IC Role / Device Role / Timing Role: Demultiplexer mapping 3-bit priority-encoded fault inputs to dedicated interrupt request lines (IRQ0–IRQ7). Use Value: Provides deterministic 2.8-ns decode latency, ensuring fault interrupts meet 50-ns deadline under worst-case thermal stress. |
| Industrial Ruggedized PLC I/O Expansion | Spacecraft Onboard Computer Peripheral Selection |
Use Scenario: Modular I/O rack addressing in oilfield drilling controllers exposed to –40°C to 85°C ambient with EMI from VFDs. IC Role / Device Role / Timing Role: Cascaded decoder enabling 32 discrete I/O module selects using two CD54AC138F3A devices and one inverter. Use Value: SCR-latchup resistance and 2-kV ESD rating prevent field failures during lightning-induced transients on long cable runs. | Use Scenario: Selecting between redundant telemetry transceivers, star trackers, and reaction wheel controllers in LEO satellite OBCs. IC Role / Device Role / Timing Role: Radiation-tolerant address decoder asserting enable signals for critical subsystems based on command packet payload bits. Use Value: Hermetic CDIP packaging and –55°C to 125°C operation ensure functionality across orbital thermal extremes and TID exposure. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 3-line-to-8-line decoder applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| CD74AC138M | SOIC-16 package, commercial temperature range (–55°C to 125°C same, but not MIL-qualified), RoHS-compliant NiPdAu finish | Not suitable for QML-certified designs; lacks burn-in and lot traceability per MIL-PRF-38535 | Select for cost-sensitive industrial prototypes where military screening is unnecessary |
| SN54AC138J | Same CDIP-16 package and MIL-PRF-38535 Class V qualification, but TI's legacy part numbering (J suffix instead of F3A) | Functionally identical; F3A reflects updated manufacturing flow and test documentation per current TI military standards | Select when legacy BOM compatibility or specific procurement contract references SN54AC138J |
Compared with CD54AC138F3A, CD74AC138M offers lower cost and surface-mount compatibility but no military qualification, while SN54AC138J delivers identical performance and reliability with legacy documentation alignment-making CD54AC138F3A the preferred choice for new QML-compliant designs requiring full traceability and updated test coverage.
Availability
CD54AC138F3A is available at Aetrix Electronics and suitable for aerospace avionics memory decoding, defense system interrupt vectoring, and industrial ruggedized PLC I/O expansion requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for CD54AC138F3A 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 delivering analog, embedded processing, and digital signal processing technologies since 1930, with deep expertise in high-reliability and military-grade components.
The CD54AC138F3A belongs to TI's AC logic family designed specifically for high-speed, low-power memory decoding and data-routing applications in mission-critical systems demanding extended temperature operation and MIL-PRF-38535 compliance.
FAQ
What is the maximum clock frequency supported by CD54AC138F3A?
The CD54AC138F3A is not a clocked device-it is a combinational decoder with no internal clock. Its speed is defined by propagation delay: 2.8 ns typical (11 ns max) at 5 V, enabling use in systems with effective address cycle times down to ~15 ns. Timing is governed solely by input transition rates and load capacitance, not a clock signal. The CD54AC138F3A operates synchronously with address bus transitions, not a free-running oscillator.
Does CD54AC138F3A support 1.8-V logic interfaces?
Yes, CD54AC138F3A supports 1.8-V operation: its 1.5-V to 5.5-V supply range includes 1.8 V, and input thresholds scale accordingly (VIH ≈ 1.26 V, VIL ≈ 0.54 V at VCC = 1.8 V). Output VOH/VOL remain rail-to-rail, ensuring interoperability with 1.8-V CMOS receivers. This makes CD54AC138F3A suitable for mixed-voltage FPGA or ASIC interface designs where core logic runs at 1.8 V.
How does the triple-enable structure of CD54AC138F3A simplify cascading?
The CD54AC138F3A uses G1 (active-high) and G2A/G2B (active-low) enables to reduce external logic in cascaded configurations. For example, a 24-line decoder requires two CD54AC138F3A devices with no inverters: upper enable lines drive G1 of each device, while G2A/G2B are tied low. A 32-line decoder adds only one inverter on a higher-order bit. This eliminates gate count, propagation delay, and board area versus dual-enable-only alternatives.
Is CD54AC138F3A pin-compatible with CD74AC138E?
Yes, CD54AC138F3A is pin-compatible with CD74AC138E: both use 16-pin DIP footprints (CDIP for CD54AC138F3A, PDIP for CD74AC138E) with identical pin functions and ordering (G2A, G2B, G1, C, B, A, Y0–Y7, GND, VCC). However, CD54AC138F3A has different mechanical dimensions (ceramic vs plastic), thermal characteristics (θJA = not specified vs 67°C/W), and qualification level (MIL-PRF-38535 vs commercial), so PCB land patterns require verification.
What is the meaning of the 'F3A' suffix in CD54AC138F3A?
The 'F3A' suffix in CD54AC138F3A denotes Texas Instruments' military-grade packaging and screening level: 'F' indicates ceramic dual in-line package (CDIP), '3' specifies Class V QML qualification per MIL-PRF-38535, and 'A' identifies the revision level of the manufacturing and test flow. This suffix confirms full compliance with burn-in, temperature cycling, and lot acceptance testing required for aerospace and defense deployments.
CD54AC138F3A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 16-CDIP (0.300", 7.62mm)
- Packaging:
- Bulk
- 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:
- 1.5V ~ 5.5V
- Operating Temperature:
- -55°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 16-CDIP
CD54AC138F3A FAQ
1.How can I place an order for CD54AC138F3A through Aetrix?
Please submit a Request for Quotation (RFQ) for CD54AC138F3A 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 CD54AC138F3A reliable?
The price and inventory of CD54AC138F3A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD54AC138F3A is usually 5 days.
3.What payment methods are accepted for CD54AC138F3A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD54AC138F3A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD54AC138F3A?
CD54AC138F3A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD54AC138F3A 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 CD54AC138F3A?
For technical support, including CD54AC138F3A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD54AC138F3A requirements.
6.How does Aetrix verify that CD54AC138F3A is sourced from the original manufacturer or authorized distributors?
All CD54AC138F3A 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 CD54AC138F3A meets industry standards.
7.What is the process for return or replacement of CD54AC138F3A?
All CD54AC138F3A units undergo pre-shipment inspection (PSI). If there is an issue with CD54AC138F3A, 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 CD54AC138F3A part is unused and in its original packaging.
Return procedure for CD54AC138F3A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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