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Texas Instruments SN74ALS540-1NS
- Part No.:
- SN74ALS540-1NS
- Manufacturer:
- Texas Instruments
- Package:
- -
- Datasheet:
-
SN74ALS540-1NS.pdf
- Description:
- INVERTER DUAL 8-INPUT 20SO
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Inventory:3,120
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Product details
Overview
SN74ALS540-1NS from Texas Instruments is an octal inverting buffer/line driver with 3-state outputs, designed for bus interface and memory address register buffering in TTL-compatible digital systems. It features inverted data flow, dual 3-state enable inputs (OE1/OE2), 48 mA low-level output drive capability (–1 version), and operates at 4.5–5.5 V supply. It is used in industrial control backplanes and legacy microprocessor address/data bus isolation.
For engineers reviewing the SN74ALS540-1NS datasheet, SN74ALS540-1NS pinout, SN74ALS540-1NS application, or SN74ALS540-1NS equivalent, key selection criteria include its 48 mA IOL rating (–1 variant), pnp-input architecture reducing DC loading, data flowthrough pinout (inputs/outputs on opposite sides), and SOP-20 package compatibility with space-constrained PCB layouts.
Technical Context
This device implements a dual-NOR 3-state control gate: either OE1 or OE2 high forces all eight Y outputs into high-impedance state. Its pnp input structure lowers input current draw versus standard TTL, improving fanout in dense logic systems.
The SN74ALS540-1NS delivers inverted output logic (Y = NOT A) with propagation delays as low as 2 ns (tPHL) and disable times down to 1 ns (tPHZ), supporting reliable timing in 5 V synchronous bus architectures up to ~50 MHz effective data rates.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Function | Inverting octal buffer with 3-state outputs (Y = NOT A) |
| Supply Voltage | 4.5–5.5 V - compatible with standard 5 V TTL and ALS logic rails |
| Low-Level Output Current (IOL) | 48 mA - enables direct driving of heavy capacitive loads or multiple TTL inputs without external buffers |
| Propagation Delay (tPHL) | 2–9 ns - ensures tight timing margins in high-speed address latching and bus arbitration |
| 3-State Enable Logic | 2-input NOR gate (OE1, OE2) - supports flexible bus sharing via active-low or OR-ed enable signals |
| Input Structure | pnp-based - reduces DC input loading to ≤ –0.2 mA, increasing fanout in cascaded ALS logic |
| Operating Temperature | 0°C to 70°C - rated for commercial-grade industrial control and instrumentation environments |
Pinout & Package
SOP-20 (Small Outline Package, 20-pin) with 0.65 mm lead pitch, 7.5 mm × 5.6 mm body, and 2.0 mm max height per JEDEC MO-150. RoHS-compliant, NIPDAU lead finish, MSL Level-1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | A1–A8 Inputs | Active-high data inputs; inverted at corresponding Y outputs |
| 9 | GND | Ground reference for logic and output stages |
| 10, 20 | VCC | Positive supply (4.5–5.5 V); dual power pins reduce switching noise |
| 11, 19 | OE1, OE2 | Active-high 3-state enable inputs; NOR logic - either high disables all outputs |
| 12, 13, 14, 15, 16, 17, 18, 20 | Y1–Y8 Outputs | Inverted, 3-state outputs; sink up to 48 mA each when enabled and low |
Key Features
| Feature | Design Value |
|---|---|
| Data flowthrough pinout | Inputs (A1–A8) on left side, outputs (Y1–Y8) on right side - simplifies PCB trace routing across bus lines |
| Enhanced output drive (–1 version) | 48 mA IOL rating at VCC = 4.75–5.25 V - eliminates need for external drivers in memory address buffering |
| pnp input stage | Reduces input current to –0.2 mA max - increases effective fanout by >2× vs. standard TTL inputs |
| Low propagation delay | tPHL/tPLH ≤ 9 ns - supports reliable operation in 20+ MHz bus clock domains |
| 3-state disable speed | tPHZ/tPLZ ≤ 12 ns - enables fast bus turnaround in bidirectional data transfer protocols |
Applications
| Industrial Backplane Bus Interface | Microprocessor Address Latching |
|---|---|
Use Scenario: Isolating CPU address bus from peripheral expansion slots in programmable logic controllers (PLCs). IC Role / Device Role / Timing Role: Inverting 3-state buffer that enables/disables address signals during DMA cycles using OE1/OE2 control. Use Value: 48 mA drive strength ensures clean signal integrity across 15 cm backplane traces loaded with 12+ TTL inputs. |
Use Scenario: Latching 8-bit address segments for EPROM or I/O port decoding in Z80- or 8085-based embedded systems. IC Role / Device Role / Timing Role: Inverting address buffer synchronized to WR or MREQ strobes to prevent address glitches during memory access. Use Value: Sub-10 ns tPHL guarantees setup time compliance for 4 MHz system clocks with 250 ns minimum address hold windows. |
| Legacy Instrumentation Data Bus | TTL-to-ALS Logic Translation |
Use Scenario: Driving multiplexed sensor data lines from analog front-end ADCs to microcontroller input ports in test equipment. IC Role / Device Role / Timing Role: 3-state line driver enabling shared data bus arbitration between multiple ADC channels. Use Value: Dual OE inputs allow independent channel gating, while pnp inputs minimize loading on high-impedance ADC output stages. |
Use Scenario: Interfacing 74LS-series control logic to newer ALS-based subsystems requiring lower input current and higher noise margin. IC Role / Device Role / Timing Role: Level-shifting and fanout buffer preserving signal polarity inversion where required by downstream decode logic. Use Value: VIH/VIL thresholds (2.0 V/0.8 V) and 400 mV noise margin ensure robust operation across voltage and temperature variation. |
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 standard (non–1) version with 24 mA max IOL | Lower drive capability limits use in high-capacitance or multi-load bus scenarios | Select only if load capacitance < 50 pF and fanout ≤ 8 TTL inputs |
| SN74ALS541-1NSR | Non-inverting octal 3-state buffer; identical –1 drive (48 mA IOL), same SOP-20 package | Requires logic inversion upstream/downstream if system design assumes inverted data path | Choose when true (non-inverted) output logic is required for address/data alignment |
Compared with SN74ALS540N, SN74ALS540-1NS provides double the output sink current for robust bus driving; compared with SN74ALS541-1NSR, it delivers inverted logic essential for specific address decode or complemented control signal generation without added gates.
Availability
SN74ALS540-1NS is available at Aetrix Electronics and suitable for industrial backplane interfaces, microprocessor address latching, and legacy instrumentation data buses requiring stable component supply across extended production lifecycles.
Supply support for SN74ALS540-1NS 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 founded in 1930, specializing in analog, embedded processing, and logic ICs with broad industrial, automotive, and communications portfolio coverage.
SN74ALS540-1NS belongs to TI's legacy ALS (Advanced Low-Power Schottky) logic family, engineered for high-speed, low-power 5 V TTL-compatible digital interfacing in industrial control and computing infrastructure.
FAQ
What is the maximum output sink current for SN74ALS540-1NS?
The SN74ALS540-1NS supports up to 48 mA per output (IOL) when VCC is maintained between 4.75 V and 5.25 V. This enhanced drive capability-specific to the "–1" variant-is confirmed in the recommended operating conditions table of the SDAS025D datasheet and enables direct connection to heavy capacitive loads or multiple TTL inputs without external amplification. The standard SN74ALS540 offers only 24 mA IOL.
Does SN74ALS540-1NS have true or inverted output logic?
SN74ALS540-1NS provides inverted output logic: each Y output equals the logical complement of its corresponding A input (Yn = NOT An). This is explicitly stated in the device description ("The SN74ALS540 provides inverted data") and distinguishes it from the SN74ALS541 series, which delivers true (non-inverted) outputs. The inversion is implemented at the gate level and requires no external components.
What package type and dimensions does SN74ALS540-1NS use?
SN74ALS540-1NS uses the SOP-20 (Small Outline Package, 20-pin) with package drawing NS, measuring 7.5 mm × 5.6 mm × 2.0 mm max height and 0.65 mm lead pitch. Its land pattern follows JEDEC MO-150, and it features NIPDAU lead finish with MSL Level-1 rating. Pin 1 orientation is quadrant Q1 in tape-and-reel packaging, per TI's package materials documentation.
How does the 3-state enable logic work on SN74ALS540-1NS?
The SN74ALS540-1NS uses a dual-input NOR gate for 3-state control: outputs go high-impedance when either OE1 or OE2 is driven high. Both enables must be low to activate the outputs. This architecture allows flexible bus sharing-e.g., OE1 tied to a system controller and OE2 to a local peripheral-without requiring external logic to combine enable signals.
Is SN74ALS540-1NS compatible with standard 5 V TTL logic levels?
Yes, SN74ALS540-1NS is fully compatible with standard 5 V TTL: VIH = 2.0 V min, VIL = 0.8 V max, VOH = 2.4 V min (at IOL = 12 mA), and VOL = 0.4 V max. Its pnp input structure draws less current than standard TTL, improving noise margin and fanout. These values are specified over 0°C to 70°C and align with TTL interface requirements defined in the SDAS025D datasheet.
SN74ALS540-1NS Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Logic Type:
- -
- Number of Elements:
- -
- Number of Bits per Element:
- -
- Input Type:
- -
- Output Type:
- -
- Current - Output High, Low:
- -
- Voltage - Supply:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
SN74ALS540-1NS FAQ
1.How can I place an order for SN74ALS540-1NS through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS540-1NS 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 SN74ALS540-1NS reliable?
The price and inventory of SN74ALS540-1NS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS540-1NS is usually 5 days.
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SN74ALS540-1NS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS540-1NS 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 SN74ALS540-1NS?
For technical support, including SN74ALS540-1NS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS540-1NS requirements.
6.How does Aetrix verify that SN74ALS540-1NS is sourced from the original manufacturer or authorized distributors?
All SN74ALS540-1NS 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 SN74ALS540-1NS meets industry standards.
7.What is the process for return or replacement of SN74ALS540-1NS?
All SN74ALS540-1NS units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS540-1NS, 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 SN74ALS540-1NS part is unused and in its original packaging.
Return procedure for SN74ALS540-1NS:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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