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Texas Instruments SN74LVC138ADR
- Part No.:
- SN74LVC138ADR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74LVC138ADR.pdf
- Description:
- IC DECODER/DEMUX 1X3:8 16SOIC
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
SN74LVC138ADR from Texas Instruments is a 3-line to 8-line decoder/demultiplexer IC operating from 1.65 V to 3.6 V, featuring active-high and dual active-low enables (G1, G2A, G2B), propagation delay as low as 5.8 ns at 3.3 V, and 5.5-V-tolerant inputs. It drives LED matrix column selection in embedded display systems with precise single-output activation.
For engineers reviewing the SN74LVC138ADR datasheet, SN74LVC138ADR pinout, SN74LVC138ADR application, or SN74LVC138ADR equivalent, this page delivers verified functional modes, real-world timing behavior, package-specific pin mapping for SOIC-16, and validated alternatives for memory decoding and data routing designs.
Technical Context
The SN74LVC138ADR implements combinational logic decoding using three binary select inputs (A, B, C) to activate exactly one of eight active-low outputs (Y0–Y7). All outputs remain HIGH unless all three enable conditions are met: G1 = HIGH, G2A = LOW, G2B = LOW - enabling direct demultiplexing without external inverters.
Its CMOS design supports mixed-voltage interfacing: inputs tolerate up to 5.5 V while operating from 1.65–3.6 V VCC, and output drive capability reaches ±24 mA at 3.0 V, ensuring robust fan-out into TTL- or LVC-level loads across industrial temperature range (–40°C to +85°C).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 1.65 V to 3.6 V - enables compatibility with 1.8-V and 3.3-V logic domains without level shifters. |
| Input Voltage Tolerance | Up to 5.5 V - allows direct connection to legacy 5-V controllers or microcontrollers without clamping diodes. |
| Max Propagation Delay | 5.8 ns at VCC = 3.3 V - ensures minimal added latency in high-speed memory address decoding paths. |
| Output Drive Strength | ±24 mA at VCC = 3.0 V - sufficient to sink/source current for driving multiple LVC inputs or LED columns directly. |
| Operating Temperature | –40°C to +85°C - qualified for industrial-grade embedded control and automation applications. |
| ESD Rating (HBM) | 2000 V - meets JEDEC JS-001 standard for robust handling in automated assembly environments. |
Pinout & Package
SN74LVC138ADR is supplied in a 16-pin SOIC (D) package measuring 9.90 mm × 3.91 mm, with 1.27-mm pitch, RoHS-compliant NiPdAu lead finish, and moisture sensitivity level (MSL) 1 (unlimited floor life at ≤30°C/60% RH).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (G2A) | Active-low enable A | Must be LOW to enable decoding; used with G2B and G1 to form 3-input AND gate for output activation. |
| 2 (G2B) | Active-low enable B | Second active-low enable; both G2A and G2B must be LOW simultaneously with G1 HIGH for function. |
| 3 (G1) | Active-high enable | Primary enable control; HIGH enables device when G2A/G2B are LOW - simplifies hierarchical decoder expansion. |
| 4 (C) | Select input C (MSB) | Most significant bit of 3-bit address; determines Y4–Y7 vs Y0–Y3 group selection when enables are active. |
| 5 (B) | Select input B | Middle bit of address; combined with A and C to uniquely select one of eight outputs. |
| 6 (A) | Select input A (LSB) | Least significant bit; final bit resolving Y0–Y1, Y2–Y3, Y4–Y5, or Y6–Y7 pair within selected group. |
| 7 (Y7) | Active-low output 7 | Low-asserted output corresponding to binary input 111 (CBA); sinks current when selected and enabled. |
| 8 (GND) | Ground reference | Primary return path for all internal logic and output currents; requires low-inductance PCB connection. |
| 9 (Y6) | Active-low output 6 | Asserts LOW for input 110; shares same timing and drive strength as other Yx outputs. |
| 10 (Y5) | Active-low output 5 | Corresponds to input 101; identical electrical characteristics to Y0–Y7 except for logical mapping. |
| 11 (Y4) | Active-low output 4 | Selected by C=1, B=0, A=0; used in 24-line decoder expansion via cascaded enables. |
| 12 (Y3) | Active-low output 3 | Asserts for C=0, B=1, A=1; supports demultiplexing where enable pins serve as data inputs. |
| 13 (Y2) | Active-low output 2 | Selected by C=0, B=1, A=0; maintains <1 ns output skew across all Yx outputs at 3.3 V. |
| 14 (Y1) | Active-low output 1 | Corresponds to C=0, B=0, A=1; compatible with 74LVC series fan-out requirements (max 10 loads). |
| 15 (Y0) | Active-low output 0 | Asserts for C=0, B=0, A=0; lowest-numbered output, commonly used as default or reset channel. |
| 16 (VCC) | Positive supply | Power rail for core logic and output drivers; requires local 0.1-µF ceramic bypass capacitor per TI layout guidelines. |
Key Features
| Feature | Design Value |
|---|---|
| 3-to-8 decoding with triple enable | Enables hierarchical address decoding (e.g., 24-line via two SN74LVC138ADR units) without external inverters. |
| 5.5-V-tolerant inputs | Permits direct interface with 5-V microcontrollers or FPGAs while powered from 1.8-V or 3.3-V rails. |
| Sub-6-ns propagation delay | Reduces total memory access time in FPGA-based or microcontroller-based address decode trees. |
| ±24-mA output drive at 3.0 V | Drives up to 10 LVC loads or directly sinks LED column current (e.g., 20-mA segments) without buffers. |
| Industrial temperature range | Validated operation from –40°C to +85°C supports deployment in factory automation and building control systems. |
Applications
| LED Matrix Column Driver | Memory Address Decoder |
|---|---|
Use Scenario: Driving 8-column LED matrix displays in industrial HMIs and status panels. IC Role / Device Role / Timing Role: Low-side column selector that asserts only one Yx output LOW per cycle to scan columns sequentially. Use Value: Eliminates need for discrete transistors or dedicated LED drivers; leverages built-in 24-mA sink capability and 5.8-ns timing for flicker-free 1 kHz refresh. |
Use Scenario: Decoding 3-bit address segments in microcontroller-based memory-mapped peripherals. IC Role / Device Role / Timing Role: Translates upper address bits into chip-select signals for SRAM, EEPROM, or I/O expanders. Use Value: Reduces MCU GPIO usage and software overhead; sub-6-ns delay ensures no wait-state insertion in 33-MHz bus systems. |
| Industrial I/O Expander Interface | Programmable Logic Enable Controller |
Use Scenario: Enabling/disabling groups of sensors or actuators in PLC backplanes. IC Role / Device Role / Timing Role: Enables eight independent power or signal paths using G1/G2A/G2B as hierarchical control inputs. Use Value: Supports hot-swap sequencing and fault isolation via enable pin prioritization - e.g., G1 as master enable, G2A/G2B as zone selectors. |
Use Scenario: Controlling clock gating or reset distribution in FPGA configuration circuits. IC Role / Device Role / Timing Role: Generates synchronized enable pulses for multiple logic blocks based on configuration register bits. Use Value: Provides deterministic, glitch-free enable assertion with <1 ns inter-output skew - critical for setup/hold timing closure. |
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 |
|---|---|---|---|
| SN74HC138N | Higher VCC range (2 V–6 V), slower max tpd (24 ns at 4.5 V), no 5.5-V input tolerance. | Suitable for legacy 5-V-only systems; not recommended for mixed-voltage or sub-2-V domains. | Choose SN74HC138N only if operating strictly at 5 V and timing budget allows >20-ns delay. |
| 74LVC138PW | TSSOP-16 package (5.00 mm × 4.40 mm), identical electrical specs and pinout to SN74LVC138ADR. | Preferred for space-constrained PCBs; same functionality but smaller footprint and thermal resistance (RθJA = 108.9°C/W). | Select 74LVC138PW when board area is limited and reflow profile supports TSSOP; otherwise SN74LVC138ADR offers lower cost and broader distributor stock. |
Compared with SN74HC138N, SN74LVC138ADR delivers 4× faster propagation and 5.5-V input tolerance for modern mixed-signal systems; versus 74LVC138PW, it trades compactness for SOIC manufacturability and thermal margin in high-density layouts.
Availability
SN74LVC138ADR is available at Aetrix Electronics and suitable for LED matrix displays, memory address decoding, industrial I/O expansion, and programmable logic enable control requiring stable component supply and full industrial temperature qualification.
Supply support for SN74LVC138ADR 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 connectivity technologies, with over 90 years of innovation in high-reliability components.
SN74LVC138ADR belongs to TI's LVC logic family, designed for low-voltage, high-speed digital interfacing in industrial, automotive, and communications equipment where power efficiency and timing precision are critical.
FAQ
What is the maximum operating frequency supported by SN74LVC138ADR?
SN74LVC138ADR does not specify a maximum clock frequency because it is a combinational logic device without internal clocking. Its usable switching rate is determined by propagation delay (5.8 ns typical at 3.3 V) and system-level timing margins. In practice, it reliably supports address decode or demux operations up to ~100 MHz in well-designed PCB layouts with controlled impedance and proper decoupling.
Can SN74LVC138ADR be used as a demultiplexer, and how?
Yes, SN74LVC138ADR functions as an 1-to-8 demultiplexer when one enable input (e.g., G1) is used as the data input while A, B, C serve as select lines. For example, applying a serial data stream to G1 and address bits to A–C routes the signal to exactly one Yx output per cycle - a technique confirmed in TI's application notes for LED scanning and signal routing.
Does SN74LVC138ADR require external pull-up resistors on its outputs?
No, SN74LVC138ADR outputs are push-pull and actively drive HIGH or LOW; external pull-ups are unnecessary. Each Yx output sources current when HIGH (up to 24 mA at 3.0 V) and sinks current when LOW. Pull-ups would conflict with active drive and risk exceeding output current limits or causing bus contention.
How does the enable logic work on SN74LVC138ADR?
SN74LVC138ADR requires all three enables to be simultaneously asserted: G1 must be HIGH, and both G2A and G2B must be LOW. This 3-input AND condition ensures precise control over decoder activation. If any enable is inactive, all Yx outputs go HIGH - a fail-safe state preventing unintended output assertion during power-up or reset sequences.
Is SN74LVC138ADR pin-compatible with older 74LS138 or 74HC138 devices?
SN74LVC138ADR shares identical pinout and logic function with 74HC138 and 74LS138 in SOIC-16 packages, but voltage levels and timing differ. While pin-for-pin replaceable on PCB, direct substitution requires verifying VCC compatibility (1.65–3.6 V vs 4.75–5.25 V), input thresholds, and timing budgets - especially since SN74LVC138ADR's 5.8-ns delay is significantly faster than LS/HC variants.
SN74LVC138ADR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74LVC
- 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:
- 1.65V ~ 3.6V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
SN74LVC138ADR FAQ
1.How can I place an order for SN74LVC138ADR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LVC138ADR 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 SN74LVC138ADR reliable?
The price and inventory of SN74LVC138ADR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LVC138ADR is usually 5 days.
3.What payment methods are accepted for SN74LVC138ADR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LVC138ADR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74LVC138ADR?
SN74LVC138ADR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LVC138ADR 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 SN74LVC138ADR?
For technical support, including SN74LVC138ADR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LVC138ADR requirements.
6.How does Aetrix verify that SN74LVC138ADR is sourced from the original manufacturer or authorized distributors?
All SN74LVC138ADR 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 SN74LVC138ADR meets industry standards.
7.What is the process for return or replacement of SN74LVC138ADR?
All SN74LVC138ADR units undergo pre-shipment inspection (PSI). If there is an issue with SN74LVC138ADR, 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 SN74LVC138ADR part is unused and in its original packaging.
Return procedure for SN74LVC138ADR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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