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Texas Instruments SN74LV138ATNSR
- Part No.:
- SN74LV138ATNSR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74LV138ATNSR.pdf
- Description:
- IC DECODER/DEMUX 1 X 3:8 16SO
- Quantity:
- Payment:
- Shipping:
Inventory:2,180
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Product details
Overview
SN74LV138ATNSR from Texas Instruments is a 3-line to 8-line decoder/demultiplexer IC designed for high-speed memory decoding and data routing. It operates from 4.5 V to 5.5 V, delivers max propagation delay of 7.6 ns at 5 V, supports TTL-voltage-compatible inputs, and features Ioff partial-power-down protection. It is used in address decoding for SRAM, Flash, and FPGA configuration interfaces.
For engineers reviewing the SN74LV138ATNSR datasheet, SN74LV138ATNSR pinout, SN74LV138ATNSR application, or SN74LV138ATNSR equivalent, key selection criteria include enable-input logic (G1 active-high, G2A/G2B active-low), output-active-low behavior, 16-pin SSOP package compatibility, and mixed-mode voltage operation across all ports.
Technical Context
The SN74LV138ATNSR implements positive-logic decoding with three binary select inputs (A, B, C) and three enable inputs (G1, G2A, G2B), where only one of eight outputs (Y0–Y7) goes low when enabled. Its architecture eliminates need for external inverters during decoder expansion - enabling 24-line decoding without added gates and 32-line decoding with only one inverter.
It integrates Ioff circuitry that disables outputs during partial power-down, preventing backflow current when VCC = 0 V while inputs remain biased. All inputs tolerate voltages up to 5.5 V independent of VCC, supporting mixed-voltage interfacing with legacy 3.3-V or 5-V logic domains.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - ensures stable operation across industrial-grade 5-V supply tolerances. |
| Max tpd | 7.6 ns at VCC = 5 V, CL = 15 pF - enables use in sub-100-MHz address decode paths without timing penalty. |
| Output Drive | IOL = 12 mA / IOH = –12 mA at VCC = 4.5–5.5 V - directly drives standard TTL loads or multiple 74LV inputs. |
| Ioff Current | ≤5 µA at VI/VO = 0–5.5 V - guarantees safe bus-hold and hot-insertion capability during power sequencing. |
| Input Voltage Range | –0.5 V to 7 V - supports overvoltage-tolerant interfacing with 3.3-V controllers driving 5-V logic rails. |
| Operating Temp | –40°C to +125°C - qualified for under-hood automotive, industrial control, and extended-temperature embedded systems. |
| ESD Rating | 2000-V HBM, 200-V MM, 1000-V CDM - meets robustness requirements for manufacturing and field-deployed equipment. |
Pinout & Package
SN74LV138ATNSR is housed in a 16-pin SSOP (Shrink Small Outline Package) with 0.65 mm pitch, 5.0 mm × 6.2 mm body size, and 2.0 mm max height per JEDEC MO-150. Pin 1 is located at the top-left corner with index marking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (G2A) | Active-low enable input | Must be low with G2B low and G1 high to activate decoding; enables hierarchical expansion without external inverters. |
| 2 (G2B) | Active-low enable input | Second enable leg; both G2A and G2B must be low for device activation - reduces fan-in count in multi-chip decode trees. |
| 3 (G1) | Active-high enable input | Primary chip-select signal; high enables function; complements G2A/G2B for flexible gating in memory-mapped systems. |
| 4 (C) | MSB binary select input | Most significant bit of 3-bit address; determines Y4–Y7 vs Y0–Y3 group selection when enabled. |
| 5 (B) | Mid-bit binary select input | Second address bit; combines with A and C to uniquely select one of eight outputs in active state. |
| 6 (A) | LSB binary select input | Least significant bit; resolves final output within selected group (e.g., CBA = 000 → Y0 low). |
| 7 (Y0) | Active-low decoded output | Asserts low when CBA = 000 and all enables satisfied; drives chip-select lines for peripheral devices. |
| 8 (Y1) | Active-low decoded output | Asserts low when CBA = 001; provides dedicated enable path for second memory bank or I/O device. |
| 9 (Y2) | Active-low decoded output | Asserts low when CBA = 010; used for third peripheral select or as demux data channel in control logic. |
| 10 (Y3) | Active-low decoded output | Asserts low when CBA = 011; supports four-device decode before requiring cascading or additional logic. |
| 11 (Y4) | Active-low decoded output | Asserts low when CBA = 100; extends decode range into upper half of 8-output space for larger memory maps. |
| 12 (Y5) | Active-low decoded output | Asserts low when CBA = 101; enables selective access to fifth peripheral without full address bus decoding. |
| 13 (Y6) | Active-low decoded output | Asserts low when CBA = 110; supports modular system design with up to eight independently enabled subsystems. |
| 14 (Y7) | Active-low decoded output | Asserts low when CBA = 111; final output for full 3-bit decode; often used for boot-ROM or diagnostic module select. |
| 15 (GND) | Ground reference | Primary return path for all internal logic and output currents; requires low-impedance PCB connection. |
| 16 (VCC) | Positive supply | 5-V nominal supply input; decoupling capacitor (0.1 µF ceramic) required within 5 mm of this pin. |
Key Features
| Feature | Design Value |
|---|---|
| TTL-voltage-compatible inputs | Accepts 0.8 V/2.0 V logic thresholds at 5-V VCC - interoperates directly with legacy 74LS and microcontroller GPIOs. |
| Ioff partial-power-down support | Disables outputs when VCC = 0 V, blocking reverse current flow - essential for hot-swap and multi-rail power sequencing. |
| Mixed-mode voltage operation | Inputs tolerate up to 5.5 V regardless of VCC level - allows interfacing between 3.3-V controllers and 5-V peripherals. |
| Low ground bounce (VOLP < 0.8 V) | Minimizes noise coupling during simultaneous output switching - improves signal integrity in dense PCB layouts. |
| High noise immunity (VIH/VIL margins) | Guaranteed 1.2 V noise margin at 5-V VCC - resists EMI-induced glitches in industrial environments. |
Applications
| Memory Address Decoding | FPGA Configuration Interface |
|---|---|
|
Use Scenario: Selecting one of eight memory banks (e.g., SRAM, Flash, EEPROM) in a microcontroller-based data logger. IC Role / Device Role / Timing Role: Acts as address-space partitioner mapping A15–A13 to Y0–Y7, enabling bank-switched memory expansion. Use Value: Reduces MCU GPIO usage by replacing discrete NAND gates; 7.6 ns tpd ensures no impact on 20-ns memory access cycles. |
Use Scenario: Routing configuration bitstreams from SPI flash to multiple FPGA configuration pins during power-up. IC Role / Device Role / Timing Role: Demultiplexes CONFIG_DONE, INIT_B, and PROGRAM_B signals based on mode strap inputs. Use Value: Eliminates need for programmable logic; active-low outputs match FPGA reset/enable polarity natively. |
| Industrial I/O Expansion | Automotive Diagnostic Module |
|
Use Scenario: Enabling eight isolated analog input channels in a PLC analog acquisition module. IC Role / Device Role / Timing Role: Drives enable inputs of eight precision op-amp buffers or multiplexers in sequence. Use Value: Ioff protection prevents leakage when analog front-end is powered down independently of main controller. |
Use Scenario: Selecting among eight CAN transceiver nodes in an OBD-II diagnostic gateway unit. IC Role / Device Role / Timing Role: Generates chip-select signals for individual CAN PHYs based on diagnostic request ID. Use Value: –40°C to +125°C rating ensures reliability in engine bay mounting; 5-V tolerance matches automotive 5-V supply rails. |
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 tpd (21 ns typ at 5 V), no Ioff, CMOS input thresholds. | Suitable for cost-sensitive consumer designs but lacks partial-power-down safety for hot-swap systems. | Choose SN74HC138N only if operating below 4.5 V or when Ioff is not required. |
| 74LVC138APW | 3.3-V optimized (1.65–3.6 V), 5.5-V tolerant inputs, 6.2 ns tpd, Ioff supported, TSSOP-16 package. | Better suited for modern low-voltage microcontrollers; incompatible with pure 5-V-only systems without level translation. | Select 74LVC138APW when main system runs at 3.3 V and requires tighter timing or lower power. |
Compared with SN74HC138N and 74LVC138APW, SN74LV138ATNSR uniquely balances 5-V operation, sub-8-ns speed, Ioff safety, and industrial temperature range - making it optimal for legacy 5-V embedded systems requiring robust power sequencing and minimal timing overhead.
Availability
SN74LV138ATNSR is available at Aetrix Electronics and suitable for memory address decoding, FPGA configuration interfaces, industrial I/O expansion, and automotive diagnostic modules requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for SN74LV138ATNSR 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 solutions, with decades of experience in high-reliability industrial and automotive IC design.
The SN74LV138ATNSR belongs to TI's LV logic family, engineered for 5-V systems requiring low-noise, fast propagation, and robust power-down behavior - targeting memory subsystems and real-time control applications.
FAQ
What is the maximum propagation delay of SN74LV138ATNSR at 5 V?
The maximum propagation delay (tpd) of SN74LV138ATNSR is 7.6 ns under recommended conditions: VCC = 5 V ± 0.5 V, CL = 15 pF, TA = –40°C to 125°C. This value applies to transitions at A/B/C, G1, or G2A/G2B inputs driving any Y output, ensuring predictable timing in high-speed memory decode paths where SN74LV138ATNSR is deployed.
Does SN74LV138ATNSR support partial power-down operation?
Yes, SN74LV138ATNSR includes Ioff circuitry that disables all outputs when VCC = 0 V, limiting Ioff current to ≤5 µA across full input/output voltage range (0–5.5 V). This feature prevents damaging backflow current during power sequencing or hot-swap events - a critical capability confirmed in the SCLS691 datasheet and validated for SN74LV138ATNSR's SSOP package.
Can SN74LV138ATNSR interface directly with 3.3-V microcontrollers?
Yes, SN74LV138ATNSR accepts input voltages up to 5.5 V independent of VCC, so 3.3-V GPIOs can drive its A, B, C, G1, G2A, and G2B pins without level shifters. Its VIH = 2.0 V and VIL = 0.8 V at 5-V VCC provide 1.2 V noise margin, ensuring reliable recognition of 3.3-V logic levels - a documented capability specific to SN74LV138ATNSR and its LV family.
What package type is used for SN74LV138ATNSR?
SN74LV138ATNSR uses a 16-pin SSOP (Shrink Small Outline Package) with 0.65 mm lead pitch, 5.0 mm × 6.2 mm body dimensions, and JEDEC MO-150 compliance. The "NS" in the part number explicitly denotes the SOP/SSOP variant, and the ordering table confirms SN74LV138ATNSR is supplied in tape-and-reel format (2000 units/reel) with marking "74LV138AT".
How does the enable-input logic work on SN74LV138ATNSR?
SN74LV138ATNSR requires G1 high AND G2A low AND G2B low to activate decoding. When enabled, outputs Y0–Y7 go low corresponding to the 3-bit code on A (LSB), B, and C (MSB); all outputs remain high otherwise. This three-input enable scheme reduces external gate count in multi-decoder systems - a functional behavior verified in the device's truth table and logic diagram for SN74LV138ATNSR.
SN74LV138ATNSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74LV
- Package/Case:
- 16-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Type:
- Decoder/Demultiplexer
- Circuit:
- 1 x 3:8
- Independent Circuits:
- 1
- Current - Output High, Low:
- 12mA, 12mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SO
SN74LV138ATNSR FAQ
1.How can I place an order for SN74LV138ATNSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LV138ATNSR 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 SN74LV138ATNSR reliable?
The price and inventory of SN74LV138ATNSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LV138ATNSR is usually 5 days.
3.What payment methods are accepted for SN74LV138ATNSR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LV138ATNSR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74LV138ATNSR?
SN74LV138ATNSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LV138ATNSR 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 SN74LV138ATNSR?
For technical support, including SN74LV138ATNSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LV138ATNSR requirements.
6.How does Aetrix verify that SN74LV138ATNSR is sourced from the original manufacturer or authorized distributors?
All SN74LV138ATNSR 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 SN74LV138ATNSR meets industry standards.
7.What is the process for return or replacement of SN74LV138ATNSR?
All SN74LV138ATNSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74LV138ATNSR, 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 SN74LV138ATNSR part is unused and in its original packaging.
Return procedure for SN74LV138ATNSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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