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Texas Instruments SN74LVC138ANSR
- Part No.:
- SN74LVC138ANSR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74LVC138ANSR.pdf
- Description:
- IC DECODER/DEMUX 1 X 3:8 16SO
- Quantity:
- Payment:
- Shipping:
Inventory:4,469
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Product details
Overview
SN74LVC138ANSR 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), three binary select inputs (A, B, C), and eight active-low outputs (Y0–Y7). It delivers 5.8 ns max propagation delay at 3.3 V and supports 5.5 V-tolerant inputs for mixed-voltage system interfacing - used in LED matrix column selection and memory address decoding.
For engineers reviewing the SN74LVC138ANSR datasheet, SN74LVC138ANSR pinout, SN74LVC138ANSR application, or SN74LVC138ANSR equivalent, key selection criteria include enable logic configuration (G1 high / G2A,G2B low), output polarity (active-low), supply voltage range (1.65–3.6 V), input voltage tolerance (up to 5.5 V), and propagation delay performance across VCC.
Technical Context
The SN74LVC138ANSR implements combinational logic decoding with three binary select lines and three enable inputs: one active-high (G1) and two active-low (G2A, G2B). All three enables must be asserted simultaneously for any output to activate; deasserting any enable forces all eight outputs high.
Its CMOS design ensures balanced drive strength (±24 mA at 3 V), 5.5 V-tolerant inputs independent of VCC, and latch-up immunity exceeding 250 mA per JESD17. The device functions as both a decoder (address selection) and demultiplexer (data routing), with any enable pin usable as a data input in demux mode.
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 buses without external clamping. |
| Max Propagation Delay | 5.8 ns at VCC = 3.3 V - supports high-speed address decoding in sub-10 ns timing-critical memory systems. |
| Output Drive Strength | ±24 mA at VCC = 3 V - sufficient to directly sink LED column current or drive multiple LVC inputs. |
| Enable Logic | G1 = high, G2A = low, G2B = low - enables hierarchical decoding expansion (e.g., 24-line decoder without inverters). |
| Output Polarity | Active-low (Y0–Y7) - simplifies low-side switching in LED matrix and relay driver applications. |
| Operating Temperature | –40°C to +85°C - qualified for industrial-grade embedded control and automation equipment. |
Pinout & Package
SOP-16 (NS package), body size 9.90 mm × 3.91 mm, 16-pin surface-mount plastic small-outline package with standard pin pitch (1.27 mm).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (G2B) | Active-low enable B | Must be low to enable decoding; tied low for standalone operation or cascaded as higher-order enable. |
| 2 (G2A) | Active-low enable A | Second active-low enable; used with G2B for multi-device expansion or gating. |
| 3 (G1) | Active-high enable | Primary enable control; high enables function, low forces all outputs high regardless of A/B/C. |
| 4 (C) | Select input C (MSB) | Most significant bit of 3-bit address; determines output group (Y0–Y3 vs Y4–Y7). |
| 5 (B) | Select input B | Mid-significance bit; combined with A and C to uniquely select one of eight outputs. |
| 6 (A) | Select input A (LSB) | Least significant bit; completes 3-bit binary decode (000–111 → Y0–Y7). |
| 7 (Y0) | Output 0 (active-low) | Asserted low when A=B=C=0; drives low-side load (e.g., LED cathode or MOSFET gate). |
| 8 (GND) | Ground reference | Return path for all internal logic and output currents; requires low-impedance PCB plane connection. |
| 9 (Y1) | Output 1 (active-low) | Asserted low when A=1, B=C=0; shares same timing and drive specs as Y0–Y7. |
| 10 (Y2) | Output 2 (active-low) | Asserted low when A=0, B=1, C=0; electrically identical to other Yx outputs. |
| 11 (Y3) | Output 3 (active-low) | Asserted low when A=B=1, C=0; used for 4-bit segment selection in display drivers. |
| 12 (Y4) | Output 4 (active-low) | Asserted low when A=B=0, C=1; enables upper half of 8-output mapping. |
| 13 (Y5) | Output 5 (active-low) | Asserted low when A=1, B=0, C=1; supports 8-channel peripheral addressing. |
| 14 (Y6) | Output 6 (active-low) | Asserted low when A=0, B=1, C=1; matches timing skew <1 ns across all outputs. |
| 15 (Y7) | Output 7 (active-low) | Asserted low when A=B=C=1; most significant output for full 3-bit decode coverage. |
| 16 (VCC) | Positive supply | Power rail for internal logic and output buffers; requires local 0.1 µF ceramic bypass capacitor. |
Key Features
| Feature | Design Value |
|---|---|
| 3-to-8 decoding with three enables | Enables hierarchical expansion: two SN74LVC138ANSR devices + one inverter yield 32-line decode without external logic gates. |
| 5.5 V-tolerant inputs | Eliminates need for external level translators when interfacing with 5 V microcontrollers or FPGAs while powered from 3.3 V or lower. |
| Sub-6 ns propagation delay | Meets tight timing budgets in high-speed memory subsystems where decoder delay must be negligible versus access time. |
| Active-low outputs | Simplifies direct connection to N-channel MOSFETs or NPN transistors in power-switching and LED-sinking applications. |
| Latch-up immunity >250 mA | Ensures robustness against transient overcurrent events in industrial environments with noisy power rails or ESD exposure. |
Applications
| LED Matrix Column Driver | Memory Address Decoder |
|---|---|
Use Scenario: Driving 8-column cathodes in an 8×8 monochrome LED display using row-scanning technique. IC Role / Device Role / Timing Role: Low-side column selector; each Yx output sinks current for one column while rows are sequentially activated. Use Value: Ensures only one column is active per scan cycle, preventing ghosting and enabling uniform brightness via PWM-controlled row timing. | Use Scenario: Translating 3-bit address bus into chip-select signals for eight peripheral ICs (e.g., ADCs, DACs, sensors) on an MCU bus. IC Role / Device Role / Timing Role: Address-space partitioner; maps A[2:0] to individual /CS lines with minimal propagation delay. Use Value: Reduces MCU GPIO usage by 5 pins versus discrete gating; maintains deterministic 5.8 ns decode latency across all selections. |
| Industrial I/O Expander | Programmable Logic Interface |
Use Scenario: Adding eight controllable digital outputs to a PLC or motion controller using limited GPIO resources. IC Role / Device Role / Timing Role: Static output enabler; G1 driven by MCU GPIO, A/B/C set via configuration register to select active channel. Use Value: Provides galvanically isolated (when paired with optocouplers) or buffered outputs capable of driving 24 mA loads per channel. | Use Scenario: Implementing custom state-machine decode logic in FPGA-adjacent control circuits where fixed-function logic is preferred over soft logic. IC Role / Device Role / Timing Role: Combinational logic block; replaces 3-input NAND/AND gates and inverters in glue logic for finite-state machines. Use Value: Reduces PCB area and BOM count versus discrete gate solutions while guaranteeing setup/hold timing compliance. |
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 (2–6 V), slower speed (24 ns @ 4.5 V), no 5.5 V-tolerant inputs | Preferred for legacy 5 V systems; unsuitable for 1.8 V operation or 5 V-to-3.3 V interfacing | 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 | Same functionality but smaller footprint; requires tighter placement and reflow profile control | Choose 74LVC138PW for space-constrained designs where SOP-16 layout area is insufficient. |
Compared with SN74HC138N and 74LVC138PW, the SN74LVC138ANSR offers optimal balance of low-voltage operation (1.65 V), 5.5 V input tolerance, and 5.8 ns speed in the widely supported SOP-16 package - making it ideal for modern mixed-voltage industrial and embedded systems requiring reliable, expandable decoding.
Availability
SN74LVC138ANSR is available at Aetrix Electronics and suitable for LED matrix displays, memory address decoding, industrial I/O expansion, and programmable logic interfaces requiring stable component supply and industrial temperature support.
Supply support for SN74LVC138ANSR 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 specializing in analog, embedded processing, and logic ICs, with leadership in industrial, automotive, and communications markets.
The SN74LVC138ANSR belongs to TI's LVC logic family, designed for low-voltage, high-speed, mixed-signal interfacing in space- and power-constrained embedded systems.
FAQ
What is the recommended operating voltage range for SN74LVC138ANSR?
The SN74LVC138ANSR operates from 1.65 V to 3.6 V. Operation below 1.65 V may cause unreliable logic transitions or increased propagation delay; above 3.6 V risks permanent damage. For stable performance across temperature, maintain VCC within this range using a well-bypassed supply - the SN74LVC138ANSR is not rated for 5 V operation despite its 5.5 V-tolerant inputs.
How does the enable logic work on SN74LVC138ANSR?
The SN74LVC138ANSR requires G1 = high, G2A = low, and G2B = low simultaneously to activate decoding. If any enable is violated (e.g., G1 low or G2A high), all eight outputs (Y0–Y7) go high-impedance (logic high). This three-input enable scheme allows flexible cascading - for example, using G1 of a second SN74LVC138ANSR as a higher-order select line controlled by an additional address bit.
Can SN74LVC138ANSR drive LEDs directly?
Yes, the SN74LVC138ANSR can directly sink up to 24 mA per output (at VCC = 3 V), sufficient for standard 5–20 mA indicator LEDs. When used as a column driver in an LED matrix, connect LED anodes to VCC and cathodes to Y0–Y7. Ensure total device supply current remains within 100 mA (per TI spec) and use series resistors to limit per-LED current - the SN74LVC138ANSR's active-low outputs simplify low-side switching without external transistors.
Is SN74LVC138ANSR pin-compatible with SN74HC138?
No, SN74LVC138ANSR is not pin-compatible with SN74HC138. While both are 16-pin 3-to-8 decoders with identical pin numbering (G2B, G2A, G1, C, B, A, Y0, GND, Y1–Y7, VCC), the SN74HC138 uses different enable logic: G1 and G2 are active-low, and G2 is a dual-input OR (G2A + G2B). The SN74LVC138ANSR uses separate G2A/G2B inputs and active-high G1 - requiring PCB redesign and firmware logic adjustment if substituted.
What package type is SN74LVC138ANSR supplied in?
The SN74LVC138ANSR is supplied in the SOP-16 (NS) package: a 16-pin plastic small-outline package with 300 mil width, 1.27 mm pin pitch, and dimensions of 9.90 mm × 3.91 mm. It is RoHS-compliant, lead-finish NIPDAU, and rated MSL Level-1 (unlimited floor life at ≤30°C/60% RH). This package is compatible with standard SOIC footprints and reflow profiles.
SN74LVC138ANSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74LVC
- Package/Case:
- 16-SOIC (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-SO
SN74LVC138ANSR FAQ
1.How can I place an order for SN74LVC138ANSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LVC138ANSR 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 SN74LVC138ANSR reliable?
The price and inventory of SN74LVC138ANSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LVC138ANSR is usually 5 days.
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SN74LVC138ANSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LVC138ANSR 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 SN74LVC138ANSR?
For technical support, including SN74LVC138ANSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LVC138ANSR requirements.
6.How does Aetrix verify that SN74LVC138ANSR is sourced from the original manufacturer or authorized distributors?
All SN74LVC138ANSR 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 SN74LVC138ANSR meets industry standards.
7.What is the process for return or replacement of SN74LVC138ANSR?
All SN74LVC138ANSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74LVC138ANSR, 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 SN74LVC138ANSR part is unused and in its original packaging.
Return procedure for SN74LVC138ANSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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