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Texas Instruments SN74AHCT138MPWREP
- Part No.:
- SN74AHCT138MPWREP
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
SN74AHCT138MPWREP.pdf
- Description:
- IC DECODER/DEMUX 1X3:8 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,189
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Product details
Overview
SN74AHCT138MPWREP from Texas Instruments is a radiation-tolerant, high-speed 3-line to 8-line decoder/demultiplexer in a 16-pin TSSOP package, featuring TTL-compatible inputs, -55°C to +125°C extended temperature operation, propagation delays as low as 6.6 ns (G1→Y), and three enable inputs (G1 active-high, G2A/G2B active-low) for cascading memory decoding systems in aerospace and defense avionics.
For engineers reviewing the SN74AHCT138MPWREP datasheet, SN74AHCT138MPWREP pinout, SN74AHCT138MPWREP application, or SN74AHCT138MPWREP equivalent, key selection criteria include its EPIC™ process qualification, latch-up immunity (>250 mA), 2000-V HBM ESD rating, 8-mA output drive capability, and compatibility with 5-V high-speed memory enable timing.
Technical Context
This device implements positive-logic binary decoding with active-low outputs (Y0–Y7), where select inputs A, B, C determine the asserted output line only when all three enables (G1 high, G2A low, G2B low) are satisfied. Its logic diagram confirms fully static CMOS design with no internal latches or clocks.
The SN74AHCT138MPWREP uses TI's EPIC™ (Enhanced-Performance Implanted CMOS) process to achieve extended temperature reliability and controlled baseline manufacturing-single assembly/test site and single fabrication site-ensuring consistent parametric performance across military-grade thermal cycling, HAST, and electromigration stress tests.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage (VCC) | 4.5 V to 5.5 V - ensures stable operation with standard 5-V logic rails and tolerance to supply droop during high-current switching. |
| Propagation Delay (tPLH/tPHL) | 6.6 ns min / 10.5 ns max (G1→Y, CL = 15 pF) - enables sub-10-ns system-level decode timing critical for fast SRAM/DRAM address decoding. |
| Output Drive (IOL/IOH) | ±8 mA - supports direct fan-out to up to 10 LSTTL loads without buffering in memory subsystems. |
| Input Voltage Thresholds | VIL = 0.8 V, VIH = 2.0 V - guarantees robust TTL-level input compatibility and noise margin in mixed-logic environments. |
| Operating Temperature | –55°C to +125°C - qualified per JEDEC standards including biased 85/85, temperature cycle, and HAST for space-grade and engine-control applications. |
| Power Dissipation Capacitance | 14 pF - enables accurate dynamic power estimation at 1 MHz clocking for thermal budgeting in sealed avionics enclosures. |
Pinout & Package
TSSOP-16 (PW) package: 4.4 mm × 5.0 mm body, 0.65 mm pitch, exposed pad not present, RoHS-compliant NiPdAu lead finish, MSL Level-1 (260°C peak reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (G2A) | Active-low enable input | Must be low to activate decoder; used with G2B and G1 to gate all eight outputs simultaneously. |
| 2 (G2B) | Active-low enable input | Second active-low enable; both G2A and G2B must be low for decode function, reducing external gating needs. |
| 3 (G1) | Active-high enable input | Primary enable control; high enables decoding; combined with G2A/G2B allows flexible cascading of multiple devices. |
| 4 (C) | MSB select input | Binary-weighted address bit (2²); determines Y4–Y7 vs Y0–Y3 group selection when enables are active. |
| 5 (B) | Mid-bit select input | Binary-weighted address bit (2¹); works with A and C to uniquely select one of eight outputs. |
| 6 (A) | LSB select input | Binary-weighted address bit (2⁰); completes 3-bit binary address decoding for full octal output mapping. |
| 7 (Y0) | Active-low decoded output | Asserted low when A=B=C=0 and all enables satisfied; drives memory chip-select or peripheral enable lines. |
| 8 (GND) | Ground reference | Return path for all internal logic and output current; requires low-impedance PCB connection to minimize ground bounce. |
| 9 (Y1) | Active-low decoded output | Asserted low when A=1, B=C=0; provides dedicated routing for second memory bank or I/O peripheral. |
| 10 (Y2) | Active-low decoded output | Asserted low when B=1, A=C=0; used in 24-line expansion schemes without external inverters. |
| 11 (Y3) | Active-low decoded output | Asserted low when A=B=1, C=0; supports demultiplexing data to four parallel channels in test equipment. |
| 12 (Y4) | Active-low decoded output | Asserted low when C=1, A=B=0; enables third memory segment in multi-bank embedded controllers. |
| 13 (Y5) | Active-low decoded output | Asserted low when A=1, C=1, B=0; used in FPGA configuration address decoding for boot ROM selection. |
| 14 (Y6) | Active-low decoded output | Asserted low when B=1, C=1, A=0; routes control signals to analog front-end modules in radar subsystems. |
| 15 (Y7) | Active-low decoded output | Asserted low when A=B=C=1; final output for highest-addressed peripheral or memory block in 8-slot expansion. |
| 16 (VCC) | Positive supply | 5-V power rail connection; requires local 0.1-μF ceramic decoupling adjacent to pin to suppress high-frequency switching noise. |
Key Features
| Feature | Design Value |
|---|---|
| Three enable inputs (G1, G2A, G2B) | Enables 24-line decoding without external inverters and 32-line decoding with only one inverter-reducing board area and signal integrity risk. |
| TTL-voltage compatible inputs | Accepts standard 0.8 V / 2.0 V logic thresholds directly from legacy 5-V microcontrollers and FPGAs without level-shifting circuitry. |
| Latch-up immunity >250 mA | Guarantees survivability under transient overvoltage or ground-bounce events in harsh automotive and aerospace power domains. |
| EPIC™ process qualification | Ensures controlled baseline manufacturing (one fab, one test site) and extended reliability validation including HAST, temperature cycling, and bond intermetallic life testing. |
| ESD protection ≥2000 V HBM | Protects against handling damage during manual assembly and field maintenance in uncontrolled environments like ground support equipment. |
Applications
| Memory Address Decoding | Aerospace Avionics Bus Control |
|---|---|
Use Scenario: Selecting one of eight SRAM or Flash memory banks in a radiation-hardened flight computer using a 3-bit address bus and system enable signals. IC Role / Device Role / Timing Role: SN74AHCT138MPWREP acts as a high-speed address decoder whose propagation delay (≤10.5 ns) is shorter than typical 55-ns memory access time-eliminating added wait states. Use Value: Enables zero-wait-state memory access in real-time control loops while maintaining full JEDEC-qualified operation from –55°C to +125°C. | Use Scenario: Routing discrete command signals from a central mission computer to eight independent sensor interface modules on a satellite payload bus. IC Role / Device Role / Timing Role: SN74AHCT138MPWREP serves as a demultiplexer where G1 carries the command strobe and A/B/C carry channel ID bits to assert individual module enables. Use Value: Provides deterministic, glitch-free channel selection with <12 ns skew between outputs-critical for synchronized sensor calibration sequences. |
| Engine Control Unit (ECU) I/O Expansion | Radar Signal Processing Subsystem |
Use Scenario: Expanding GPIO capability in an automotive ECU by decoding microcontroller port bits to drive eight solenoid drivers or diagnostic LEDs. IC Role / Device Role / Timing Role: SN74AHCT138MPWREP functions as a static I/O expander with active-low outputs directly sinking 8 mA per channel into driver transistors. Use Value: Eliminates need for external pull-up resistors or buffer ICs, reducing BOM count and improving thermal margin in under-hood 125°C environments. | Use Scenario: Enabling eight parallel ADC channels in a phased-array radar receiver based on timing-critical trigger pulses from a master sequencer. IC Role / Device Role / Timing Role: SN74AHCT138MPWREP operates as a synchronous demux where G1 is edge-triggered by the sequencer clock and A/B/C select ADC subset. Use Value: Delivers sub-11 ns channel-enable matching across all eight outputs-preserving time-of-arrival accuracy within ±50 ps for beamforming algorithms. |
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 |
|---|---|---|---|
| SN74AHCT138MDREP | Same die, SOIC-16 package (D), 2500-unit reel, θJA = 73°C/W vs 108°C/W for PW | Better thermal dissipation in convection-cooled industrial enclosures; larger footprint limits high-density PCBs | Select when board layout permits SOIC and thermal management prioritizes lower junction rise over size. |
| SN54AHCT138 | Military QML-38534 Class V qualified, same TSSOP-16 or CDIP-16 options, identical AC/DC specs | Required for DoD-specified hardware; includes full MIL-STD-883 screening (including burn-in and lot acceptance tests) | Choose only when contractual program requirements mandate QML certification-not for performance advantage. |
Compared with SN74AHCT138MDREP, the SN74AHCT138MPWREP trades 35°C/W higher thermal resistance for 44% smaller PCB area and improved high-frequency signal integrity; versus SN54AHCT138, it omits MIL-STD-883 screening but retains identical electrical behavior and JEDEC extended-temperature qualification.
Availability
SN74AHCT138MPWREP is available at Aetrix Electronics and suitable for aerospace avionics, engine control units, radar subsystems, and radiation-tolerant industrial controllers requiring stable component supply across extended temperature and long product lifecycles.
Supply support for SN74AHCT138MPWREP 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 connectivity solutions with emphasis on reliability, longevity, and industrial/military-grade qualification.
The SN74AHCT138MPWREP belongs to TI's enhanced-product (EP) logic family, designed specifically for high-reliability applications demanding extended temperature operation, controlled manufacturing, and DMS mitigation in defense, space, and transportation systems.
FAQ
What is the maximum operating temperature range certified for the SN74AHCT138MPWREP?
The SN74AHCT138MPWREP is fully qualified for continuous operation from –55°C to +125°C per JEDEC JESD22-A108 and industry-standard extended-temperature reliability testing-including biased 85/85, temperature cycling, and HAST-making it suitable for engine bay and space-based deployments where thermal extremes are routine.
Does the SN74AHCT138MPWREP support true 3-state outputs or only active-low/open-drain behavior?
The SN74AHCT138MPWREP does not feature 3-state outputs; all eight Y0–Y7 outputs are push-pull (totem-pole) with active-low assertion and passive-high (VCC) state. When disabled (any enable inactive), outputs remain statically high-no high-impedance mode is implemented, so external pull-ups are unnecessary.
Can the SN74AHCT138MPWREP be used as a demultiplexer, and how is data routed?
Yes-the SN74AHCT138MPWREP functions as a demultiplexer when G1 is used as the data input and A/B/C as select lines: a high on G1 propagates to exactly one Y output (determined by A/B/C), while low on G1 forces all Y outputs high. This enables serial-to-parallel data distribution in test instrumentation and digital pattern generators.
What is the absolute maximum supply voltage rating for the SN74AHCT138MPWREP, and what happens above that limit?
The absolute maximum VCC rating for the SN74AHCT138MPWREP is 7 V. Exceeding this-even briefly-risks permanent damage due to oxide breakdown or junction overvoltage. TI specifies recommended operation strictly at 4.5 V to 5.5 V; sustained operation above 5.5 V voids qualification and may cause accelerated parametric drift or catastrophic failure.
How does the latch-up immunity specification of >250 mA apply in practical circuit design?
The >250 mA latch-up immunity (per JESD17) means the SN74AHCT138MPWREP can withstand transient current injection-such as from ESD events or ground bounce-without entering a destructive high-current thyristor state. Designers should still implement proper PCB grounding, decoupling, and I/O protection, but this rating validates robustness in electrically noisy mil-aero environments.
SN74AHCT138MPWREP Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHCT
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Decoder/Demultiplexer
- Circuit:
- 1 x 3:8
- Independent Circuits:
- 1
- Current - Output High, Low:
- 8mA, 8mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -55°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP
SN74AHCT138MPWREP FAQ
1.How can I place an order for SN74AHCT138MPWREP through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHCT138MPWREP 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 SN74AHCT138MPWREP reliable?
The price and inventory of SN74AHCT138MPWREP are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHCT138MPWREP is usually 5 days.
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Once your SN74AHCT138MPWREP 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 SN74AHCT138MPWREP?
For technical support, including SN74AHCT138MPWREP datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHCT138MPWREP requirements.
6.How does Aetrix verify that SN74AHCT138MPWREP is sourced from the original manufacturer or authorized distributors?
All SN74AHCT138MPWREP 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 SN74AHCT138MPWREP meets industry standards.
7.What is the process for return or replacement of SN74AHCT138MPWREP?
All SN74AHCT138MPWREP units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHCT138MPWREP, 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 SN74AHCT138MPWREP part is unused and in its original packaging.
Return procedure for SN74AHCT138MPWREP:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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