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Texas Instruments 74AC11138DR
- Part No.:
- 74AC11138DR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
74AC11138DR.pdf
- Description:
- IC DECODER/DEMUX 1X3:8 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,290
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Product details
Overview
74AC11138DR from Texas Instruments is a 3-line to 8-line decoder/demultiplexer in SOIC-16 package, designed for high-speed memory decoding and data routing. It features three enable inputs (G1 active-high, G2A/G2B active-low), propagation delays as low as 5.1 ns at 5 V, and operates across –40°C to 85°C. Used in address decoding for SRAM/ROM systems where minimal system delay is critical.
For engineers reviewing the 74AC11138DR datasheet, 74AC11138DR pinout, 74AC11138DR application, or 74AC11138DR equivalent, this page delivers verified functional modes, real-world switching characteristics at 3.3 V and 5 V, thermal resistance (130°C/W), latch-up immunity (500 mA at 125°C), and SOIC-specific layout guidance - all confirmed from TI's production datasheet SCAS042C (May 2024).
Technical Context
The 74AC11138DR implements positive-logic decoding with binary select inputs A, B, C and three independent enables (G1, G2A, G2B) enabling cascaded 24- and 32-line decoding without external inverters. Its EPIC™ 1-µm CMOS process ensures rail-to-rail output swing and low dynamic power dissipation (51 pF typical Cpd).
Functional operation requires simultaneous evaluation of all three enables: only when G1 = HIGH and G2A = G2B = LOW does the device decode A–C to assert exactly one of eight active-low outputs (Y0–Y7). Unused inputs must be tied to VCC or GND to prevent floating states, per TI's layout guidelines.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 3 V to 5.5 V - supports mixed-voltage system interfacing and robust noise margin across industrial range. |
| Propagation Delay (tPLH/tPHL) | 5.1 ns min / 7.9 ns max at 5 V - enables sub-10 ns address decoding critical for >100 MHz memory subsystems. |
| Output Drive (IOL/IOH) | ±24 mA at 4.5–5.5 V - sufficient to drive multiple TTL loads or fan-out to 10+ 74AC inputs without buffers. |
| Latch-up Immunity | 500 mA typical at 125°C - meets stringent JEDEC JESD78 requirements for high-reliability embedded control. |
| Power Dissipation Capacitance | 51 pF - quantifies dynamic power consumption (P = Cpd × V² × f); enables accurate thermal modeling at 1 MHz. |
| Operating Temperature | –40°C to +85°C - qualified for industrial-grade applications including motor control and instrumentation. |
| Junction-to-Ambient RθJA | 130°C/W (SOIC-16) - defines maximum allowable power dissipation (e.g., 385 mW at 50°C ambient rise). |
Pinout & Package
74AC11138DR uses a 16-pin SOIC (D) package measuring 9.9 mm × 6.0 mm (body: 9.9 mm × 3.9 mm), with center-aligned VCC (pin 12) and GND (pin 4) to suppress high-speed switching noise.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 5–8, 16 | Y1–Y7, Y0 | Active-low decoded outputs - each asserts LOW when selected; all remain HIGH otherwise (3-state disabled). |
| 9, 10 | G2B, G2A | Active-low enable inputs - both must be LOW for decode to activate; simplifies hierarchical enable tree design. |
| 11 | G1 | Active-high enable input - provides orthogonal enable control; allows demultiplexing by using G1 as data input. |
| 13–15 | C, B, A | Binary address inputs - MSB-to-LSB order (CBA) selects Y0–Y7; compatible with standard address bus routing. |
| 4 | GND | Ground reference - center-pin placement minimizes ground bounce during simultaneous output transitions. |
| 12 | VCC | Power supply - center-pin placement reduces supply noise coupling and improves high-frequency stability. |
Key Features
| Feature | Design Value |
|---|---|
| Three enable inputs (G1, G2A, G2B) | Enables direct 24-line decoding without external inverters and 32-line decoding with only one inverter - reduces board area and signal path delay. |
| Center-pin VCC and GND | Minimizes simultaneous switching noise (SSN) in high-speed memory systems by shortening return current paths and reducing inductance. |
| EPIC™ 1-µm CMOS process | Delivers 500 mA latch-up immunity and rail-to-rail VOH/VOL performance - eliminates need for external clamping or level-shifting in mixed-logic designs. |
| Low propagation delay (5.1 ns min) | Ensures decoder delay is negligible versus typical fast SRAM access times (>10 ns), preserving system timing budget. |
| Industrial temperature range (–40°C to 85°C) | Validated for continuous operation in motor drives, PLC I/O modules, and industrial computing without derating. |
Applications
| Memory Address Decoding | High-Speed Data Demultiplexing |
|---|---|
|
Use Scenario: Selecting one of eight SRAM chips in a 64 kB memory bank using A15–A13 address lines. IC Role / Device Role / Timing Role: 3-to-8 decoder translating upper address bits into chip-select signals with <8 ns propagation delay. Use Value: Eliminates timing penalty in memory access cycles - decoder delay is less than SRAM tAA (12 ns), preserving full system bandwidth. |
Use Scenario: Routing a single serial data stream to one of eight test instruments in automated validation equipment. IC Role / Device Role / Timing Role: Demultiplexer using G1 as data input and A–C as channel select; outputs drive 50 Ω transmission lines. Use Value: Supports >100 Mbps data switching with deterministic 5.1 ns channel selection latency and no inter-channel skew. |
| Cascaded Logic Expansion | Industrial Control I/O Selection |
|
Use Scenario: Building a 32-line decoder for FPGA configuration memory mapping using two 74AC11138DR devices. IC Role / Device Role / Timing Role: Master-slave decode pair where G1 of slave is driven by Y0 of master; no external logic required. Use Value: Reduces component count by 33% versus discrete gate-based expansion - lowers BOM cost and PCB layer count. |
Use Scenario: Enabling one of eight analog sensor signal chains in a programmable logic controller (PLC) backplane. IC Role / Device Role / Timing Role: Output-enable controller asserting active-low enable to precision ADCs or signal conditioners. Use Value: Provides glitch-free channel selection via synchronized G2A/G2B gating - prevents transient errors during reconfiguration. |
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 |
|---|---|---|---|
| SN74HC138DR | Slower propagation (19 ns typ at 6 V), lower drive (±4 mA), wider VCC range (2–6 V). | Better suited for battery-powered logic where speed is secondary to ultra-low static current (2 µA ICC). | Select when operating below 3 V or requiring <10 µA quiescent current - not recommended for >25 MHz address buses. |
| 74ACT138SCX | Faster (4.5 ns typ), higher drive (±24 mA), but obsolete packaging (ceramic DIP) and no RoHS compliance. | Legacy military/aerospace systems requiring MIL-PRF-38535 qualification and hermetic sealing. | Choose only for drop-in replacement in existing through-hole designs; not suitable for new SMT production. |
Compared with SN74HC138DR and 74ACT138SCX, the 74AC11138DR uniquely balances 5 ns-class speed, 24 mA drive, SOIC-16 RoHS compliance, and industrial temperature support - making it optimal for modern high-density memory and data-routing PCBs.
Availability
74AC11138DR is available at Aetrix Electronics and suitable for high-speed memory decoding, industrial I/O selection, and automated test equipment requiring stable component supply and long-term manufacturing continuity.
Supply support for 74AC11138DR 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 over 90 years of innovation in industrial, automotive, and communications markets.
The 74AC11138DR belongs to TI's AC-series advanced CMOS logic family, engineered for high-speed, low-noise digital interfacing in memory subsystems and real-time control applications.
FAQ
What is the maximum clock frequency supported by the 74AC11138DR?
The 74AC11138DR is not a clocked device - it is a combinational decoder with no internal clock. Its effective maximum operating frequency depends on propagation delay and system setup/hold timing. With 5.1 ns minimum tPLH at 5 V, it supports address decode rates up to ~100 MHz in well-designed memory systems where address lines are stable before enable assertion.
Can the 74AC11138DR operate at 3.3 V supply voltage?
Yes, the 74AC11138DR is fully specified for 3.3 V ± 0.3 V operation. At this voltage, propagation delay increases to 7.2 ns (tPLH, G1→Y), output drive drops to ±12 mA (IOL), and VIH/VIL thresholds scale accordingly (VIH = 2.1 V min). All parameters remain guaranteed across –40°C to 85°C.
How does the enable logic work on the 74AC11138DR?
The 74AC11138DR requires G1 = HIGH AND G2A = LOW AND G2B = LOW for normal decoding. If any enable condition fails, all outputs (Y0–Y7) go HIGH. This three-input enable scheme allows flexible hierarchical control - e.g., G1 can serve as a global enable while G2A/G2B manage local bank selection.
Is the 74AC11138DR pin-compatible with the 74LS138?
No - although both are 3-to-8 decoders, the 74AC11138DR has different pinout: Y0 is on pin 16 (not pin 1), and enables G2A/G2B occupy pins 9–10 (vs. 4–5 on 74LS138). Direct replacement requires PCB redesign. Functional equivalence exists, but mechanical compatibility does not.
What thermal considerations apply to the 74AC11138DR in SOIC-16 package?
The 74AC11138DR in SOIC-16 has RθJA = 130°C/W. At 5.5 V and full output loading (24 mA × 8 outputs), worst-case power dissipation is ~1.06 W, causing ~138°C junction rise above ambient - exceeding absolute max. Derating is essential: limit concurrent active outputs and verify board copper area per TI's thermal guidelines in Section 4.3.
74AC11138DR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AC
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- 3V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
74AC11138DR FAQ
1.How can I place an order for 74AC11138DR through Aetrix?
Please submit a Request for Quotation (RFQ) for 74AC11138DR 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 74AC11138DR reliable?
The price and inventory of 74AC11138DR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74AC11138DR is usually 5 days.
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4.How is shipping managed for 74AC11138DR?
74AC11138DR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74AC11138DR 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 74AC11138DR?
For technical support, including 74AC11138DR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74AC11138DR requirements.
6.How does Aetrix verify that 74AC11138DR is sourced from the original manufacturer or authorized distributors?
All 74AC11138DR 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 74AC11138DR meets industry standards.
7.What is the process for return or replacement of 74AC11138DR?
All 74AC11138DR units undergo pre-shipment inspection (PSI). If there is an issue with 74AC11138DR, 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 74AC11138DR part is unused and in its original packaging.
Return procedure for 74AC11138DR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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