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Texas Instruments SN74LVC138ADBR
- Part No.:
- SN74LVC138ADBR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
SN74LVC138ADBR.pdf
- Description:
- IC DECODER/DEMUX 1X3:8 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,398
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Product details
Overview
SN74LVC138ADBR from Texas Instruments is a 3-line to 8-line decoder/demultiplexer in SSOP-16 package, operating from 1.65 V to 3.6 V with 5.8 ns max propagation delay at 3.3 V, inputs tolerant to 5.5 V, and designed for memory decoding and LED matrix column selection in industrial control systems.
For engineers reviewing the SN74LVC138ADBR datasheet, SN74LVC138ADBR pinout, SN74LVC138ADBR application, or SN74LVC138ADBR equivalent, key selection criteria include enable input logic (G1 high-active, G2A/G2B low-active), active-low output behavior, 16-pin SSOP thermal performance (RθJA = 100.1°C/W), and compatibility with mixed-voltage 3.3 V/5 V signal environments.
Technical Context
The SN74LVC138ADBR implements a binary-select decoder with three address inputs (A, B, C) and three enable inputs (G1, G2A, G2B) that collectively determine which of eight outputs (Y0–Y7) is driven LOW; all other outputs remain HIGH when enabled. Its CMOS design ensures balanced drive strength and fast edge rates.
It supports demultiplexing by repurposing an enable input as data path-e.g., G1 accepts serial data while A/B/C select destination line-and features latch-up immunity exceeding 250 mA per JESD17, making it suitable for noise-prone industrial bus interfaces.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply voltage range | 1.65 V to 3.6 V - enables direct interface with 1.8 V, 2.5 V, and 3.3 V logic domains without level shifters |
| Input voltage tolerance | Up to 5.5 V - allows safe connection to legacy 5 V controllers or microcontrollers without external clamping |
| Max propagation delay | 5.8 ns at 3.3 V - ensures minimal added latency in high-speed memory decode paths or real-time LED scanning |
| Output drive strength | ±24 mA at 3 V - sufficient to directly sink/source LED column current or drive multiple CMOS inputs |
| Operating temperature | –40°C to +85°C - qualified for industrial ambient conditions in factory automation and building control equipment |
| ESD rating (HBM) | 2000 V - meets standard handling requirements for automated PCB assembly and field service |
Pinout & Package
SN74LVC138ADBR uses the SSOP-16 (DB) package: 4.4 mm × 5.3 mm body, 0.65 mm lead pitch, gull-wing leads, RoHS-compliant NiPdAu finish, and moisture sensitivity level (MSL) 1 (unlimited floor life at ≤30°C/60% RH).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (G2B) | Active-low enable B | Must be LOW to activate decoder; used with G2A and G1 to gate entire output bank |
| 2 (G2A) | Active-low enable A | Second low-active enable; both G2A and G2B must be LOW for function |
| 3 (G1) | Active-high enable | Must be HIGH to enable; can serve as data input in demux mode |
| 4 (C) | Select input C (MSB) | Most significant bit of 3-bit address; determines Y4–Y7 vs Y0–Y3 group |
| 5 (B) | Select input B | Mid-significance bit; combines with A and C to uniquely select one of eight outputs |
| 6 (A) | Select input A (LSB) | Least significant bit; final bit resolving exact output line (e.g., A=0,B=1,C=1 → Y3) |
| 7 (Y7) | Output 7 (active-low) | Drives LOW only when A=B=C=1 and all enables active; otherwise HIGH |
| 8 (GND) | Ground reference | Primary return path for all internal logic and output currents; requires low-impedance PCB plane |
| 9 (Y6) | Output 6 (active-low) | Asserted when A=0,B=1,C=1 - used for dedicated peripheral addressing or LED column drive |
| 10 (Y5) | Output 5 (active-low) | Selected on A=1,B=0,C=1 - supports discrete I/O expansion in PLC modules |
| 11 (Y4) | Output 4 (active-low) | Activated for A=0,B=0,C=1 - commonly assigned to status indicator or fault line |
| 12 (Y3) | Output 3 (active-low) | Corresponds to A=1,B=1,C=0 - used in multiplexed sensor readout circuits |
| 13 (Y2) | Output 2 (active-low) | Asserted when A=0,B=1,C=0 - interfaces with optocoupler inputs in isolation stages |
| 14 (Y1) | Output 1 (active-low) | Selected on A=1,B=0,C=0 - drives backlight segments in HMI displays |
| 15 (Y0) | Output 0 (active-low) | Lowest-address output; asserted when A=B=C=0 - often tied to reset or initialization line |
| 16 (VCC) | Power supply | Supplies core logic and output drivers; requires local 0.1 µF ceramic bypass capacitor |
Key Features
| Feature | Design Value |
|---|---|
| 3-to-8 decoding with three enable inputs | Enables hierarchical address decoding (e.g., two SN74LVC138ADBR devices expand to 24-line decode without inverters) |
| 5.5 V-tolerant inputs | Eliminates need for external level translators when interfacing with 5 V microcontrollers or FPGAs |
| Active-low outputs with high-impedance disable | Ensures fail-safe HIGH state on all outputs when any enable is inactive - prevents bus contention |
| Low dynamic power consumption | Typical ICC = 10 µA at 3.6 V - supports low-power standby modes in battery-backed systems |
| High noise immunity | VOLP < 0.8 V and VOHV > 2 V at 3.3 V - suppresses ground bounce and undershoot in dense layouts |
Applications
| LED Matrix Column Driver | Industrial I/O Expansion |
|---|---|
|
Use Scenario: Driving 8-column common-anode LED display in factory HMIs where microcontroller GPIO is limited. IC Role / Device Role / Timing Role: Low-side column selector; each Yx output sinks current for one column while row drivers source current. Use Value: Enables 64-pixel (8×8) display using only 3 address lines + 2 enables, reducing MCU pin count and simplifying firmware scan logic. |
Use Scenario: Expanding digital output capability in programmable logic controller (PLC) base units. IC Role / Device Role / Timing Role: Address decoder for 8-channel solid-state relay (SSR) bank; G1 controlled by CPU write strobe. Use Value: Provides deterministic 1-of-8 activation with <5.8 ns delay, ensuring synchronized SSR switching across industrial cycles. |
| Memory Address Decoding | Peripheral Select Logic |
|
Use Scenario: Selecting one of eight SRAM or flash memory banks in embedded data logger with ARM Cortex-M4. IC Role / Device Role / Timing Role: High-speed address decoder placed between CPU address bus and chip-select lines of memory ICs. Use Value: Propagation delay (≤6.7 ns at 3.3 V) stays below typical 10 ns memory access time, eliminating wait states. |
Use Scenario: Routing SPI or UART signals to one of eight sensor nodes on a shared bus in building automation gateway. IC Role / Device Role / Timing Role: Demultiplexer where G1 carries data and A/B/C select destination node address. Use Value: Allows single full-duplex UART to serve eight isolated RS-485 transceivers without software arbitration overhead. |
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 tpd (21 ns @ 4.5 V), no 5.5 V input tolerance | Requires level-shifting for 3.3 V MCU interfacing; unsuitable for mixed-voltage systems | Choose for legacy 5 V-only designs where speed is non-critical and cost is primary |
| 74LVT138PW | 3.3 V only operation (3.0–3.6 V), higher drive (±32 mA), TTL-compatible inputs | Cannot accept 5 V inputs safely; incompatible with 1.8 V or 2.5 V logic without buffers | Prefer when driving heavy capacitive loads or interfacing strictly with 3.3 V TTL-level sources |
Compared with SN74HC138N and 74LVT138PW, SN74LVC138ADBR uniquely supports 1.65–3.6 V operation with 5.5 V-tolerant inputs, enabling direct integration into modern low-voltage MCUs while maintaining backward compatibility with 5 V peripherals - a critical advantage in transitional industrial designs.
Availability
SN74LVC138ADBR is available at Aetrix Electronics and suitable for industrial I/O expansion, LED matrix displays, and memory decoding applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for SN74LVC138ADBR 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 company headquartered in Dallas, Texas, specializing in analog, embedded processing, and connectivity technologies for industrial, automotive, and communications markets.
The SN74LVC138ADBR belongs to TI's LVC logic family, engineered for low-voltage, high-speed operation in space-constrained industrial control and instrumentation systems where voltage scalability and robustness are essential.
FAQ
What is the maximum clock/data rate supported by SN74LVC138ADBR?
The SN74LVC138ADBR does not operate on a clock; it is asynchronous. Its maximum usable toggle rate depends on propagation delay and system timing margins. With 5.8 ns max tpd at 3.3 V, it supports address/data changes up to approximately 170 MHz in ideal conditions - though practical limits are set by board layout, load capacitance, and enable timing constraints in the SN74LVC138ADBR application circuit.
Can SN74LVC138ADBR drive LEDs directly without current-limiting resistors?
No. While SN74LVC138ADBR outputs can sink up to 24 mA per pin at 3 V, direct LED connection without series resistors risks overcurrent, thermal stress, and inconsistent brightness due to VOL variation. Each output must use a discrete current-limiting resistor calculated from forward voltage, desired current, and SN74LVC138ADBR's guaranteed VOL (e.g., 0.55 V at 24 mA, 3 V).
How do the enable inputs (G1, G2A, G2B) interact in SN74LVC138ADBR?
In SN74LVC138ADBR, all three enables must be simultaneously active for decoding: G1 must be HIGH, and both G2A and G2B must be LOW. If any enable is inactive, all outputs (Y0–Y7) go HIGH regardless of A/B/C state. This triple-enable structure allows cascading - e.g., using one SN74LVC138ADBR's Y0 to drive G1 of a second device for 24-line expansion.
Is SN74LVC138ADBR compatible with 1.8 V microcontrollers?
Yes. SN74LVC138ADBR is fully specified down to 1.65 V VCC, with guaranteed VIH/VIL thresholds at 1.8 V (VIH ≥ 1.2 V, VIL ≤ 0.6 V). Its 5.5 V-tolerant inputs also accept 1.8 V logic levels safely, making SN74LVC138ADBR suitable for direct interface with 1.8 V MCUs like MSP430FRxx or nRF52840 without level translation.
What is the thermal resistance (RθJA) of SN74LVC138ADBR in its SSOP-16 package?
The SN74LVC138ADBR in SSOP-16 (DB) package has a junction-to-ambient thermal resistance (RθJA) of 100.1°C/W under standard JEDEC test conditions (1-layer board, 1 in² copper). This value assumes proper PCB layout with thermal vias and adequate copper pour; actual board-level RθJA may improve to ~65°C/W with optimized 2+ layer thermal design.
SN74LVC138ADBR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74LVC
- Package/Case:
- 16-SSOP (0.209", 5.30mm 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-SSOP
SN74LVC138ADBR FAQ
1.How can I place an order for SN74LVC138ADBR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LVC138ADBR 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 SN74LVC138ADBR reliable?
The price and inventory of SN74LVC138ADBR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LVC138ADBR is usually 5 days.
3.What payment methods are accepted for SN74LVC138ADBR?
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4.How is shipping managed for SN74LVC138ADBR?
SN74LVC138ADBR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LVC138ADBR 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 SN74LVC138ADBR?
For technical support, including SN74LVC138ADBR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LVC138ADBR requirements.
6.How does Aetrix verify that SN74LVC138ADBR is sourced from the original manufacturer or authorized distributors?
All SN74LVC138ADBR 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 SN74LVC138ADBR meets industry standards.
7.What is the process for return or replacement of SN74LVC138ADBR?
All SN74LVC138ADBR units undergo pre-shipment inspection (PSI). If there is an issue with SN74LVC138ADBR, 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 SN74LVC138ADBR part is unused and in its original packaging.
Return procedure for SN74LVC138ADBR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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