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Texas Instruments SN74ALS540-1DW
- Part No.:
- SN74ALS540-1DW
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74ALS540-1DW.pdf
- Description:
- IC BUFFER INVERT 5.5V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,188
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Product details
Overview
SN74ALS540-1DW from Texas Instruments is an octal inverting buffer/line driver with 3-state outputs, designed for bus interfacing and memory address register buffering in TTL-compatible digital systems. It features dual output-enable inputs (OE1/OE2), pnp input structure for reduced DC loading, data flowthrough pinout (inputs and outputs on opposite sides), and supports 48 mA low-level output current per channel at VCC = 4.75–5.25 V.
For engineers reviewing the SN74ALS540-1DW datasheet, SN74ALS540-1DW pinout, SN74ALS540-1DW application, or SN74ALS540-1DW equivalent, this device is selected for high-drive 3-state bus driving where inverted logic, thermal efficiency (θJA = 58°C/W), and PCB layout simplification via split-side I/O are critical design requirements.
Technical Context
The SN74ALS540-1DW implements a dual 2-input NOR gate for 3-state control: either OE1 or OE2 high forces all eight Y outputs into high-impedance. Its pnp input stage lowers input current draw versus standard TTL, improving fan-out in dense logic systems.
As the -1 variant of SN74ALS540, it delivers enhanced sink capability (IOL = 48 mA vs. 24 mA in standard version) under tightly regulated VCC (4.75–5.25 V), while maintaining identical propagation delays (tPLH ≤ 12 ns, tPHL ≤ 9 ns) and enable/disable timing (tPZH ≤ 15 ns, tPZL ≤ 20 ns) at CL = 50 pF.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Function | Inverting octal buffer with 3-state outputs - provides signal inversion and bus isolation simultaneously |
| VCC Operating Range | 4.5 V to 5.5 V - compatible with standard 5 V TTL supply rails |
| IOL (Max) | 48 mA per output (at VCC = 4.75–5.25 V) - drives heavy capacitive loads or multiple TTL inputs |
| tPLH / tPHL | 2–12 ns - ensures fast data transfer in high-speed address/data buses |
| θJA Thermal Impedance | 58°C/W (SOIC-DW package) - enables reliable operation up to 70°C ambient without forced cooling |
| Input Structure | pnp-based - reduces DC input current (IIL = –0.2 mA max), minimizing loading on upstream drivers |
| 3-State Control | Dual NOR-gated OE1/OE2 - any high enable input disables all outputs, supporting flexible bus arbitration |
Pinout & Package
SN74ALS540-1DW is housed in a 20-pin SOIC (DW) package measuring 7.5 mm × 12.83 mm × 2.65 mm, with gull-wing leads, RoHS-compliant NiPdAu finish, and moisture sensitivity level (MSL) 1 (260°C peak reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | A1–A8 Inputs | Active-high data inputs; inverted and gated to corresponding Y outputs |
| 9 | GND | Ground reference for logic and power return path |
| 10, 20 | VCC | Positive supply (4.5–5.5 V); dual VCC pins reduce supply impedance and improve noise immunity |
| 11, 19 | OE1, OE2 | Active-high 3-state enable inputs; NOR logic means either high disables all outputs |
| 12, 13, 14, 15, 16, 17, 18, 20 | Y1–Y8 Outputs | Inverted, 3-state buffered outputs - high-impedance when OE1/OE2 asserted, else Yn = NOT(An) |
Key Features
| Feature | Design Value |
|---|---|
| Data flowthrough pinout | Inputs (A1–A8) on left side, outputs (Y1–Y8) on right side - eliminates layer crossings and reduces trace length in PCB layout |
| pnp input structure | Reduces input current to ≤0.2 mA (IIL), enabling higher fan-out without signal degradation |
| Enhanced drive (-1 version) | 48 mA sink capability per output supports legacy TTL bus loads and long trace routing |
| Dual 3-state enable | OE1 and OE2 provide redundant or split-bus control - simplifies system-level bus arbitration logic |
| Thermal performance | 58°C/W junction-to-ambient thermal resistance allows sustained operation at full load in industrial ambient |
Applications
| Memory Address Buffering | Microprocessor Bus Interface |
|---|---|
Use Scenario: Driving 16-bit address lines from a microprocessor to multiple memory ICs with shared address decoding. IC Role / Device Role / Timing Role: Inverting 3-state buffer isolating CPU address bus from memory subsystem; enabled during memory access cycles. Use Value: Prevents bus contention during DMA or peripheral access; 48 mA drive ensures clean edges across 10+ cm traces and 5+ TTL loads. |
Use Scenario: Interfacing an 8-bit data bus between a Z80 CPU and peripheral controllers with bidirectional handshake signals. IC Role / Device Role / Timing Role: Unidirectional inverting driver for write-data path; controlled by WR# and BUSACK# via OE1/OE2 logic. Use Value: Data flowthrough layout minimizes skew; pnp inputs reduce loading on CPU data pins, preserving setup/hold margins. |
| Industrial Control Backplane | Legacy Instrumentation I/O Expansion |
Use Scenario: Distributing isolated control signals across a 20-slot backplane with daisy-chained enable lines. IC Role / Device Role / Timing Role: Octal buffer providing gain and isolation for TTL-level control commands (e.g., reset, init, select). Use Value: Dual OE inputs allow hierarchical enable tree; 58°C/W θJA supports convection-cooled enclosures up to 70°C ambient. |
Use Scenario: Expanding digital I/O on a benchtop oscilloscope with fixed-function ASICs requiring inverted strobe and latch signals. IC Role / Device Role / Timing Role: Generating inverted, high-current strobes (e.g., LATCH#, STB#) synchronized to internal clock domains. Use Value: Guaranteed tPLH ≤ 12 ns and VOL ≤ 0.5 V at 48 mA ensure reliable edge timing and noise margin for synchronous capture circuits. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting 3-state buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS540N | Same logic function and pinout, but PDIP package (N) and lower IOL rating (24 mA) | Suitable for prototyping or low-density boards where thermal budget allows larger package | Select when board space permits DIP and drive requirement ≤24 mA per line |
| SN74ALS541-1DW | Non-inverting counterpart in same SOIC-DW package; identical -1 drive (48 mA) and timing specs | Used where signal polarity must be preserved (e.g., direct address mirroring without external inversion) | Choose when true (non-inverted) output logic is required; otherwise not functionally interchangeable |
Compared with SN74ALS540N, SN74ALS540-1DW offers superior thermal performance and higher drive in compact SOIC format; compared with SN74ALS541-1DW, it provides complementary logic polarity - both alternatives require explicit verification of signal inversion needs and layout constraints.
Availability
SN74ALS540-1DW is available at Aetrix Electronics and suitable for memory subsystem design, microprocessor bus interfacing, industrial backplane signal distribution, and legacy instrumentation I/O expansion requiring stable component supply across extended product lifecycles.
Supply support for SN74ALS540-1DW 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 over 50 years of innovation in industrial, automotive, and communications markets.
The SN74ALS540-1DW belongs to TI's advanced low-power Schottky (ALS) logic family, engineered for high-speed, low-noise digital interfacing in resource-constrained embedded and control systems.
FAQ
What is the maximum output sink current supported by SN74ALS540-1DW?
The SN74ALS540-1DW supports a maximum low-level output current (IOL) of 48 mA per channel, but only when VCC is maintained within the narrow range of 4.75 V to 5.25 V. This enhanced drive is the defining feature of the "-1" suffix variant and exceeds the 24 mA rating of the standard SN74ALS540. Operation outside this VCC window reverts to the standard 24 mA limit.
Does SN74ALS540-1DW have the same pinout as SN74ALS540N?
Yes, SN74ALS540-1DW shares identical pin assignment with SN74ALS540N and all other variants in the SN74ALS540 family. Pin 1 is the index corner (OE1), A1–A8 occupy pins 2–8, GND is pin 9, VCC appears on pins 10 and 20, OE2 is pin 11, and Y1–Y8 span pins 12–19. The SOIC-DW and PDIP-N packages maintain full pin-to-pin compatibility despite differing physical dimensions and thermal characteristics.
How does the dual output-enable (OE1/OE2) logic work on SN74ALS540-1DW?
The SN74ALS540-1DW uses a 2-input NOR gate for 3-state control: if either OE1 (pin 11) or OE2 (pin 19) is driven high, all eight Y outputs enter high-impedance state. Both enables must be low for normal inverted data transmission (Yn = NOT(An)). This architecture allows flexible bus arbitration - for example, OE1 can serve as local chip select while OE2 acts as global bus grant signal.
Is SN74ALS540-1DW RoHS compliant and what is its MSL rating?
Yes, SN74ALS540-1DW is RoHS compliant with NiPdAu lead finish and carries a moisture sensitivity level (MSL) rating of Level-1 at 260°C peak reflow. As a Level-1 device, it has unlimited floor life and requires no baking prior to soldering, making it suitable for standard SMT assembly processes without special handling protocols.
Can SN74ALS540-1DW replace SN74ALS541-1DW in a design?
No - SN74ALS540-1DW and SN74ALS541-1DW are not drop-in replacements due to opposite logic polarity: SN74ALS540-1DW inverts inputs (Yn = NOT(An)), while SN74ALS541-1DW passes them true (Yn = An). Swapping them without circuit revision will invert critical control or address signals, causing functional failure. Verify signal polarity requirements before substitution.
SN74ALS540-1DW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Logic Type:
- Buffer, Inverting
- Number of Elements:
- 1
- Number of Bits per Element:
- 8
- Input Type:
- -
- Output Type:
- 3-State
- Current - Output High, Low:
- 15mA, 48mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
SN74ALS540-1DW FAQ
1.How can I place an order for SN74ALS540-1DW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS540-1DW 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 SN74ALS540-1DW reliable?
The price and inventory of SN74ALS540-1DW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS540-1DW is usually 5 days.
3.What payment methods are accepted for SN74ALS540-1DW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS540-1DW transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS540-1DW?
SN74ALS540-1DW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS540-1DW 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 SN74ALS540-1DW?
For technical support, including SN74ALS540-1DW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS540-1DW requirements.
6.How does Aetrix verify that SN74ALS540-1DW is sourced from the original manufacturer or authorized distributors?
All SN74ALS540-1DW 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 SN74ALS540-1DW meets industry standards.
7.What is the process for return or replacement of SN74ALS540-1DW?
All SN74ALS540-1DW units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS540-1DW, 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 SN74ALS540-1DW part is unused and in its original packaging.
Return procedure for SN74ALS540-1DW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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