My Inquiry
My Account
Texas Instruments SN74ALS540-1NSR
- Part No.:
- SN74ALS540-1NSR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74ALS540-1NSR.pdf
- Description:
- IC BUFFER INVERT 5.5V 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:2,002
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SN74ALS540-1NSR from Texas Instruments is an octal inverting buffer/line driver with 3-state outputs, designed for bus interfacing and memory address register buffering in industrial digital systems. It features pnp input structure for reduced DC loading, data flowthrough pinout (inputs and outputs on opposite sides), and supports 48 mA low-level output current (IOL) at VCC = 4.75–5.25 V - enabling direct drive of heavy capacitive loads or multiple TTL inputs.
For engineers reviewing the SN74ALS540-1NSR datasheet, SN74ALS540-1NSR pinout, SN74ALS540-1NSR application, or SN74ALS540-1NSR equivalent, key selection criteria include its -1 version's enhanced 48 mA sink capability, SOP-20 (NS) package compatibility with high-density PCB layouts, 3-state NOR-gated enable logic (OE1/OE2), and ALS-family propagation delays under 14 ns.
Technical Context
This device implements dual 2-input NOR gates controlling eight independent inverting 3-state outputs. Its pnp input stage lowers input current draw versus standard TTL, reducing loading on preceding logic stages. The data flowthrough layout places all eight A-inputs on one side and Y-outputs on the opposite side - optimizing trace routing for parallel bus applications.
Output enable is active-low logic: either OE1 or OE2 high forces all outputs into high-impedance state. Propagation delay (tPLH/tPHL) ranges from 2–12 ns at VCC = 4.5–5.5 V and CL = 50 pF, while enable/disable times (tPZH/tPZL/tPHZ/tPLZ) span 1–28 ns - supporting reliable timing in synchronous address/data latching circuits.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - compatible with standard 5 V TTL/ALS logic rails and tolerant of supply ripple. |
| IOL (max) | 48 mA - enables driving up to 16 standard TTL loads or long PCB traces without external buffers. |
| VOH / VOL | ≥2.0 V @ IOL = 48 mA / ≤0.5 V @ IOL = 48 mA - ensures robust noise margins in noisy industrial environments. |
| tPLH / tPHL | 2–12 ns - supports >50 MHz bus operation with margin when paired with matched trace lengths. |
| θJA (NS) | 60 °C/W - allows sustained operation at full load in ambient temperatures up to 70 °C with minimal heatsinking. |
| Input Structure | pnp-based - reduces input current to ≤ –0.2 mA (IIL), minimizing loading on microcontroller GPIO or FPGA I/O banks. |
| 3-State Control | Dual NOR-gated OE1/OE2 - provides flexible bus arbitration: either enable line high disables all outputs simultaneously. |
Pinout & Package
SOP-20 (NS) package: 20-pin small-outline plastic package, 0.65 mm lead pitch, 7.5 mm × 5.6 mm body size, 2.0 mm max height, RoHS-compliant NiPdAu lead finish, MSL Level-1 (unlimited reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | A1–A8 Inputs | Inverting data inputs; accept standard TTL/ALS logic levels (VIH ≥ 2 V, VIL ≤ 0.8 V). |
| 9 | GND | Ground reference for all internal circuitry and output drivers. |
| 10, 11 | OE1, OE2 | Active-high 3-state enable inputs; NOR logic - either high disables all Y outputs. |
| 12, 13, 14, 15, 16, 17, 18, 19 | Y1–Y8 Outputs | Inverting 3-state outputs; sink up to 48 mA each when enabled and low. |
| 20 | VCC | +5 V supply rail; decoupling capacitor (0.1 µF) required adjacent to pin for noise suppression. |
Key Features
| Feature | Design Value |
|---|---|
| Inverting octal buffer function | Provides true logic inversion (A → ¬Y) across all eight channels - simplifies address/data polarity alignment in memory subsystems. |
| Data flowthrough pinout | Inputs (A1–A8) on left side, outputs (Y1–Y8) on right side - eliminates layer crossings and minimizes crosstalk in dense 8-bit bus routing. |
| -1 version enhanced drive | Guaranteed 48 mA IOL (vs. 24 mA in standard version) - eliminates need for external driver stages in high-fanout control bus designs. |
| pnp input structure | Reduces input current to ≤ –0.2 mA (IIL) - preserves drive strength of weak-sourcing controllers like legacy microprocessors or CPLD I/O. |
| 3-state NOR enable architecture | Single-point bus disable via OE1 or OE2 - enables clean, glitch-free bus sharing among multiple devices without external logic. |
Applications
| Industrial PLC Backplane Interface | Legacy Microprocessor Address Latch |
|---|---|
Use Scenario: Isolating and driving 8-bit address/data buses between CPU and peripheral modules in programmable logic controller racks. IC Role / Device Role / Timing Role: Inverting 3-state buffer providing level-shifting, fanout expansion, and bus contention control. Use Value: 48 mA sink capability drives long backplane traces and multiple slot connectors without signal degradation or timing skew. |
Use Scenario: Latching and buffering 8-bit address lines from Z80 or 8085 microprocessors to static RAM or I/O peripherals. IC Role / Device Role / Timing Role: Octal inverting latch driver synchronizing address setup/hold timing with memory access cycles. Use Value: Sub-14 ns propagation delay ensures setup time compliance with 4–6 MHz CPU clock domains and fast SRAM access. |
| Test Equipment Signal Conditioning | Automated Test Fixture Bus Driver |
Use Scenario: Conditioning digital stimulus signals in automated test equipment where precise edge integrity and load tolerance are critical. IC Role / Device Role / Timing Role: Inverting buffer isolating pattern generator outputs from variable capacitive DUT loads. Use Value: pnp inputs minimize source loading, while 3-state control enables dynamic bus reconfiguration during multi-step test sequences. |
Use Scenario: Driving 8-bit control buses to relay matrices, multiplexers, or sensor interface boards in production test fixtures. IC Role / Device Role / Timing Role: High-current 3-state driver enabling simultaneous activation of multiple test paths without ground bounce. Use Value: Dual OE pins allow hierarchical enable sequencing - e.g., global reset followed by per-subsystem activation - reducing inrush current peaks. |
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 functionality but PDIP-20 package; IOL limited to 24 mA (non–1 version). | Preferred for prototyping or through-hole assembly; unsuitable for high-current or space-constrained designs. | Select only if SOP-20 footprint is unavailable and 24 mA drive suffices. |
| SN74LS240N | LS-family equivalent; lower IOL (15 mA), higher ICC (25 mA), slower tPLH (25 ns typical), no -1 variant. | Compatible with legacy LS-based systems but lacks enhanced drive and speed of ALS-1 series. | Choose only for backward compatibility with existing LS designs where power and speed budgets permit. |
Compared with SN74ALS540N and SN74LS240N, SN74ALS540-1NSR delivers 100% higher output sink current in a surface-mount package with 50% faster propagation delay - making it optimal for modern industrial control boards requiring compact layout, high reliability, and robust bus drive.
Availability
SN74ALS540-1NSR is available at Aetrix Electronics and suitable for industrial PLC backplanes, legacy microprocessor address latching, and automated test fixture bus driving requiring stable component supply across extended product lifecycles.
Supply support for SN74ALS540-1NSR 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-grade logic families.
SN74ALS540-1NSR belongs to the ALS (Advanced Low-Power Schottky) logic family, engineered for high-speed, low-power operation in industrial control, instrumentation, and legacy computing systems.
FAQ
What is the maximum output sink current for SN74ALS540-1NSR?
The SN74ALS540-1NSR guarantees a minimum low-level output current (IOL) of 48 mA per channel when VCC is between 4.75 V and 5.25 V. This is the defining feature of the "-1" suffix variant and exceeds the 24 mA rating of the standard SN74ALS540. Operation outside this VCC range reverts to the standard 24 mA specification. The SN74ALS540-1NSR must be operated within its recommended conditions to ensure this performance.
Does SN74ALS540-1NSR support true or inverted data output?
SN74ALS540-1NSR provides inverted data output: each Yn output is the logical complement of its corresponding An input (Yn = ¬An). This distinguishes it from the SN74ALS541-1NSR, which provides true (non-inverting) outputs. The inversion is inherent to the device's internal circuit design and cannot be disabled or configured.
What is the purpose of the dual OE inputs (OE1 and OE2) on SN74ALS540-1NSR?
The SN74ALS540-1NSR uses a 2-input NOR gate for 3-state control: if either OE1 or OE2 is driven high, all eight outputs enter high-impedance state. This architecture allows flexible bus arbitration - for example, OE1 can serve as a system-wide enable while OE2 acts as a local subsystem override. Both inputs must be low to activate the outputs.
Can SN74ALS540-1NSR be used in place of SN74ALS540NSR?
Yes, SN74ALS540-1NSR is a direct functional upgrade to SN74ALS540NSR, sharing identical pinout, package (SOP-20), and logic behavior. The only difference is the guaranteed 48 mA IOL (vs. 24 mA) under specified VCC conditions. No PCB changes are required, but designers should verify that the higher output current does not exceed trace current-carrying capacity or cause excessive voltage drop in the ground path.
What thermal considerations apply to SN74ALS540-1NSR in continuous operation?
SN74ALS540-1NSR has a junction-to-ambient thermal resistance (θJA) of 60 °C/W in the NS package. At maximum rated IOL = 48 mA per output and worst-case VOL = 0.5 V, total power dissipation can reach ~200 mW. With a 70 °C ambient limit, junction temperature remains below 190 °C - well within the 150 °C storage limit but approaching the absolute maximum operating junction temperature. Adequate board copper area and airflow are recommended for sustained full-load operation.
SN74ALS540-1NSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 20-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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-SO
SN74ALS540-1NSR FAQ
1.How can I place an order for SN74ALS540-1NSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS540-1NSR 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 SN74ALS540-1NSR reliable?
The price and inventory of SN74ALS540-1NSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS540-1NSR is usually 5 days.
3.What payment methods are accepted for SN74ALS540-1NSR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS540-1NSR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS540-1NSR?
SN74ALS540-1NSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS540-1NSR 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 SN74ALS540-1NSR?
For technical support, including SN74ALS540-1NSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS540-1NSR requirements.
6.How does Aetrix verify that SN74ALS540-1NSR is sourced from the original manufacturer or authorized distributors?
All SN74ALS540-1NSR 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 SN74ALS540-1NSR meets industry standards.
7.What is the process for return or replacement of SN74ALS540-1NSR?
All SN74ALS540-1NSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS540-1NSR, 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 SN74ALS540-1NSR part is unused and in its original packaging.
Return procedure for SN74ALS540-1NSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SN74ALS540-1NSR Tags
-
SN74LVC1G17DBVR
Texas Instruments
-
SN74LVC1G07DCKR
Texas Instruments
-
SN74LVC1G17DCKR
Texas Instruments
-
SN74LVC1G07DBVR
Texas Instruments
-
SN74LVC1G125DCKR
Texas Instruments
-
SN74AHCT1G126DBVR
Texas Instruments
-
SN74LVC1G125DBVR
Texas Instruments
-
SN74AHCT1G125DBVR
Texas Instruments
-
SN74LVC2G17DBVR
Texas Instruments
-
SN74LVC2G07DCKR
Texas Instruments
-
SN74LVC1G34DCKR
Texas Instruments
-
SN74LVC2G17DCKR
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
