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Texas Instruments SN74LV138ATPWT
- Part No.:
- SN74LV138ATPWT
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
SN74LV138ATPWT.pdf
- Description:
- IC DECODER/DEMUX 1X3:8 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,242
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Product details
Overview
SN74LV138ATPWT 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 partial-power-down via Ioff, and features TTL-voltage-compatible inputs. It is used in address decoding for SRAM/Flash systems where low-latency signal selection is critical.
For engineers reviewing the SN74LV138ATPWT datasheet, SN74LV138ATPWT pinout, SN74LV138ATPWT application, or SN74LV138ATPWT equivalent, key selection criteria include enable-input logic (G1 active-high, G2A/G2B active-low), output drive capability (±12 mA), Ioff protection for mixed-voltage system power sequencing, and TSSOP-16 package compatibility with space-constrained PCB layouts.
Technical Context
The SN74LV138ATPWT implements positive-logic 3-to-8 decoding with three binary select inputs (A, B, C) and three enable inputs (G1, G2A, G2B) - two active-low and one active-high - enabling hierarchical expansion without external inverters. Its architecture allows direct demultiplexing by using an enable input as data input.
It integrates Ioff circuitry that disables outputs during partial power-down, preventing backflow current when VCC = 0 V while other supplies remain active. All inputs tolerate voltages up to 7 V, supporting mixed-mode voltage operation across interfaces operating at different rail levels.
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 5 V, CL = 15 pF - enables use in sub-100-MHz address decode paths without adding system timing margin. |
| Ioff Support | Active at VCC = 0 V - permits safe hot-insertion and power sequencing in multi-rail systems without external isolation. |
| Output Drive | ±12 mA - sufficient to directly drive standard CMOS/TTL loads or fan-out to multiple downstream gates. |
| Input Compatibility | TTL-voltage compatible - accepts 2 V VIH / 0.8 V VIL thresholds, allowing direct interface with legacy 5-V logic families. |
| Operating Temp | –40°C to +125°C - qualified for under-hood automotive, industrial control, and extended-temperature embedded applications. |
Pinout & Package
TSSOP-16 (PW) package: 4.4 mm × 5.0 mm body, 0.65 mm pitch, 1.2 mm max height, exposed pad not present, RoHS-compliant NIPDAU finish, MSL Level-1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (G2A) | Active-low enable input | Must be low to activate decoder; used with G2B and G1 for hierarchical expansion. |
| 2 (G2B) | Active-low enable input | Second active-low enable; both G2A and G2B must be low for function enable. |
| 3 (G1) | Active-high enable input | Must be high to activate decoder; complements G2A/G2B for flexible gating logic. |
| 4 (C) | MSB select input | Binary address bit C; determines high-order output group (Y4–Y7 vs Y0–Y3). |
| 5 (B) | Mid select input | Binary address bit B; combines with A and C to uniquely select one of eight outputs. |
| 6 (A) | LSB select input | Binary address bit A; least-significant bit of 3-bit address bus. |
| 7 (Y0) | Active-low decoded output | Asserted low when A=B=C=0 and all enables active; drives memory chip-select or peripheral enable. |
| 8 (GND) | Ground reference | Primary return path for all internal logic and output currents; requires low-impedance PCB connection. |
| 9 (Y1) | Active-low decoded output | Asserted low when A=1, B=C=0; used for discrete peripheral selection in multi-device systems. |
| 10 (Y2) | Active-low decoded output | Asserted low when B=1, A=C=0; supports modular I/O expansion with dedicated line assignment. |
| 11 (Y3) | Active-low decoded output | Asserted low when A=B=1, C=0; enables partitioned memory mapping in banked architectures. |
| 12 (Y4) | Active-low decoded output | Asserted low when C=1, A=B=0; routes control signals to upper-half peripherals in 8-device clusters. |
| 13 (Y5) | Active-low decoded output | Asserted low when A=1, C=1, B=0; provides deterministic addressing for FPGA configuration slaves. |
| 14 (Y6) | Active-low decoded output | Asserted low when B=1, C=1, A=0; used in interrupt vector decoding for microcontroller peripherals. |
| 15 (Y7) | Active-low decoded output | Asserted low when A=B=C=1; selects highest-priority device or final memory segment in linear map. |
| 16 (VCC) | Supply voltage | 5-V nominal power rail; bypass capacitor required within 10 mm for noise suppression during switching. |
Key Features
| Feature | Design Value |
|---|---|
| Partial-power-down support | Ioff limits reverse current to ≤5 µA when VCC = 0 V, enabling safe inter-rail sequencing in multi-supply systems. |
| Low propagation delay | 7.6 ns typical at 5 V ensures decoder delay is negligible versus typical 55-ns SRAM access time. |
| Mixed-voltage interface | Inputs tolerate up to 7 V, allowing direct connection to 3.3-V or 5-V controllers without level shifters. |
| Expandable enable architecture | G1 (active-high), G2A/G2B (active-low) allow 24-line decoding without external inverters. |
| Robust ESD protection | Exceeds 2000-V HBM, 200-V MM, and 1000-V CDM - suitable for handling in non-EPA environments. |
Applications
| Memory Address Decoding | Peripheral Select Logic |
|---|---|
Use Scenario: Decoding 3-bit address bus to generate eight independent chip-select signals for parallel SRAM or Flash devices in a microcontroller-based data logger. IC Role / Device Role / Timing Role: SN74LV138ATPWT acts as a synchronous address decoder, translating CPU address lines into active-low enables synchronized with memory read/write strobes. Use Value: Eliminates need for discrete NAND gates or CPLD resources, reducing BOM count and layout area while maintaining <8 ns decode latency. | Use Scenario: Selecting among eight UART, SPI, or GPIO expanders in an industrial PLC backplane with shared data/address bus. IC Role / Device Role / Timing Role: SN74LV138ATPWT serves as a static peripheral selector, asserting individual /CS lines based on configuration register bits. Use Value: Enables deterministic, glitch-free peripheral activation with no additional timing constraints beyond setup/hold on address lines. |
| Interrupt Vector Mapping | FPGA Configuration Interface |
Use Scenario: Assigning priority-encoded interrupt requests from eight sensor nodes to a single microcontroller IRQ pin using daisy-chained priority encoding. IC Role / Device Role / Timing Role: SN74LV138ATPWT functions as a fixed-priority encoder front-end, driving interrupt request lines to a priority arbiter circuit. Use Value: Provides hardware-level interrupt prioritization without firmware overhead or CPU polling cycles. | Use Scenario: Routing configuration clock (CCLK) and data (DIN) to one of eight FPGA configuration slaves in a modular reconfigurable computing system. IC Role / Device Role / Timing Role: SN74LV138ATPWT operates as a configuration channel demultiplexer, gating CCLK/DIN to selected FPGA based on mode pins. Use Value: Reduces FPGA programming infrastructure complexity by eliminating per-device clock buffers and data switches. |
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 | Slower max tpd (21 ns @ 5 V), no Ioff, wider VCC range (2–6 V), DIP-16 only | Limited to through-hole prototyping or legacy designs; unsuitable for partial-power-down systems | Select when cost-sensitive, low-speed, or DIP-layout compatibility is required. |
| SN74LVC138APW | Same TSSOP-16 package, 3.3-V optimized (1.65–3.6 V), 6.7 ns tpd, Ioff supported | Requires level-shifting for 5-V systems; better for modern low-voltage MCU interfaces | Select for 3.3-V domains where lower power and faster timing outweigh 5-V compatibility needs. |
Compared with SN74HC138N and SN74LVC138APW, the SN74LV138ATPWT uniquely balances 5-V robustness, industrial temperature range, Ioff safety, and TSSOP-16 footprint - making it optimal for new 5-V embedded designs requiring reliability across power transitions.
Availability
SN74LV138ATPWT is available at Aetrix Electronics and suitable for memory decoding, peripheral selection, interrupt routing, and FPGA configuration applications requiring stable component supply and long-term industrial availability.
Supply support for SN74LV138ATPWT 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 focus on reliability, scalability, and broad ecosystem support.
The SN74LV138ATPWT belongs to TI's LV logic family, engineered for high-speed 5-V operation with enhanced power-down safety and mixed-signal interface resilience in industrial and automotive control systems.
FAQ
What is the maximum propagation delay of the SN74LV138ATPWT at 5 V?
The SN74LV138ATPWT has a maximum propagation delay (tpd) of 7.6 ns at VCC = 5 V with CL = 15 pF, measured from any select or enable input to any Y output. This value is specified across –40°C to 125°C and ensures minimal timing impact in high-speed memory decode paths where the SN74LV138ATPWT is deployed.
Does the SN74LV138ATPWT support partial-power-down operation?
Yes, the SN74LV138ATPWT includes Ioff circuitry that disables all outputs when VCC = 0 V, limiting reverse current to ≤5 µA. This feature protects the device and upstream circuitry during power sequencing in multi-rail systems - a key design advantage over standard HC or HCT variants, and integral to the SN74LV138ATPWT's role in robust industrial hardware.
Can the SN74LV138ATPWT interface directly with 3.3-V microcontrollers?
Yes, the SN74LV138ATPWT accepts TTL-compatible input thresholds (VIH = 2 V min, VIL = 0.8 V max) and tolerates input voltages up to 7 V, enabling direct connection to 3.3-V GPIOs without level shifters. However, its outputs swing rail-to-rail (0 V to VCC), so interfacing with 3.3-V receivers requires VCC = 3.3 V - which the SN74LV138ATPWT does not support; it is strictly 4.5–5.5 V only.
What package type is used for the SN74LV138ATPWT?
The SN74LV138ATPWT uses a TSSOP-16 (PW) package: 4.4 mm × 5.0 mm body, 0.65 mm lead pitch, 1.2 mm maximum height, with NIPDAU lead finish and MSL Level-1 rating. This compact surface-mount package supports high-density PCB layouts and automated assembly, distinguishing the SN74LV138ATPWT from through-hole or larger SOIC alternatives.
How many enable inputs does the SN74LV138ATPWT have, and what are their logic polarities?
The SN74LV138ATPWT has three enable inputs: G1 (active-high), G2A (active-low), and G2B (active-low). All three must be asserted simultaneously - G1 = high, G2A = low, G2B = low - for the decoder to operate. This asymmetric enable structure reduces external logic when cascading multiple SN74LV138ATPWT devices for larger decode trees.
SN74LV138ATPWT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74LV
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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-TSSOP
SN74LV138ATPWT FAQ
1.How can I place an order for SN74LV138ATPWT through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LV138ATPWT 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 SN74LV138ATPWT reliable?
The price and inventory of SN74LV138ATPWT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LV138ATPWT is usually 5 days.
3.What payment methods are accepted for SN74LV138ATPWT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LV138ATPWT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74LV138ATPWT?
SN74LV138ATPWT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LV138ATPWT 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 SN74LV138ATPWT?
For technical support, including SN74LV138ATPWT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LV138ATPWT requirements.
6.How does Aetrix verify that SN74LV138ATPWT is sourced from the original manufacturer or authorized distributors?
All SN74LV138ATPWT 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 SN74LV138ATPWT meets industry standards.
7.What is the process for return or replacement of SN74LV138ATPWT?
All SN74LV138ATPWT units undergo pre-shipment inspection (PSI). If there is an issue with SN74LV138ATPWT, 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 SN74LV138ATPWT part is unused and in its original packaging.
Return procedure for SN74LV138ATPWT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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