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Texas Instruments SN74AHCT540NSR
- Part No.:
- SN74AHCT540NSR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74AHCT540NSR.pdf
- Description:
- IC BUFFER INVERT 5.5V 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:5,907
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Product details
Overview
SN74AHCT540NSR from Texas Instruments is an octal noninverting buffer/driver with 3-state outputs, designed for bus line driving and memory address register buffering in 5-V digital systems. It features TTL-compatible inputs, ±8 mA output drive, 4.4 V minimum VOH at –8 mA, 0.36 V maximum VOL at 8 mA, and operates from –40°C to 125°C.
For engineers reviewing the SN74AHCT540NSR datasheet, SN74AHCT540NSR pinout, SN74AHCT540NSR application, or SN74AHCT540NSR equivalent, key selection criteria include 3-state control architecture (dual active-low OE), input voltage compatibility with legacy TTL logic, bus-hold immunity requirements, thermal performance in SOP-20 packages, and compatibility with high-speed 5-V CMOS system interfaces.
Technical Context
The SN74AHCT540NSR implements dual independent 3-state enable controls (OE1 and OE2) feeding eight noninverting buffer channels. Each channel's output enters high-impedance when either OE is high, enabling bidirectional bus arbitration without external logic.
Its TTL-voltage-compatible inputs accept 0.8 V VIH and 2.0 V VIH thresholds, ensuring interoperability with 5-V TTL families. Propagation delay is 6.0 ns typical (CL = 15 pF), with 1 ns minimum pulse width tolerance and 20 ns/V input transition rate support.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - ensures stable operation across industrial-grade 5-V rail tolerances |
| Output Drive | ±8 mA - sufficient to drive standard 50-pF loads at ≤10 ns propagation with defined VOH/VOL |
| VOH / VOL | ≥3.94 V / ≤0.36 V at ±8 mA - meets 5-V CMOS logic-high/low thresholds under full load |
| Propagation Delay | 6.0 ns typical (A→Y, CL = 15 pF) - supports ≤100 MHz bus toggle rates in point-to-point configurations |
| Input Compatibility | TTL-voltage - accepts 0.8 V low and 2.0 V high thresholds, enabling direct interface with 74LS/74F logic |
| ESD Rating | ±2000 V HBM - exceeds JEDEC JESD22-A114A, suitable for assembly environments without Class 0 ESD controls |
| Operating Temp | –40°C to 125°C - qualified for extended-temperature industrial and automotive under-hood applications |
Pinout & Package
SOP-20 (NS) package: 7.2 mm × 6.2 mm body, 0.65 mm lead pitch, gull-wing leads, RoHS-compliant NiPdAu finish, MSL Level-1 (260°C reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | OE1, OE2 | Active-low 3-state enables - independent control of two groups of four outputs each |
| 2–9 | A1–A8 | Buffer inputs - TTL-compatible, no internal pullups; must be tied to VCC/GND if unused |
| 10 | GND | Ground reference - requires local 0.1 µF bypass capacitor per VCC pin |
| 11–18 | Y1–Y8 | Noninverting 3-state outputs - high-impedance when OE1 or OE2 is high; fanout ≥20 LS-TTL loads |
| 20 | VCC | 5-V supply - decoupling required within 5 mm of pin; supports ICC ≤40 µA static current |
Key Features
| Feature | Design Value |
|---|---|
| Dual 3-state enable | Independent OE1/OE2 pins allow partitioned bus control - e.g., split memory/data lanes without glue logic |
| TTL input compatibility | VIH = 2.0 V min, VIL = 0.8 V max - eliminates level-shifting when interfacing with legacy 74LS systems |
| High noise immunity | 2000 V HBM ESD rating and latch-up immunity >250 mA - reduces field failure risk in noisy industrial environments |
| Low power consumption | ICC ≤40 µA at 5.5 V - enables use in always-on subsystems without thermal derating |
| Thermal robustness | RθJA = 60°C/W (NS package) - sustains continuous 8-mA output loading at 125°C ambient with <10°C junction rise |
Applications
| Memory Address Buffering | Industrial Bus Interface |
|---|---|
Use Scenario: Driving 16-bit address lines from a microcontroller to SRAM or Flash memory in programmable logic controllers. IC Role / Device Role / Timing Role: Noninverting buffer with 3-state outputs isolates MCU address bus during DMA cycles and enables shared memory access. Use Value: Ensures clean 5-V address transitions with ≤6 ns skew across all 8 bits, preventing memory access collisions in real-time control loops. | Use Scenario: Interfacing a PLC CPU module to multiple I/O expansion cards over a parallel backplane bus. IC Role / Device Role / Timing Role: Octal driver buffers address/data signals while enabling/disabling segments via OE1/OE2 for hot-swap isolation. Use Value: Dual OE control allows dynamic segmentation of 16-bit bus into two 8-bit zones, reducing contention and simplifying firmware address mapping. |
| Legacy System Upgrade | Test Equipment Signal Conditioning |
Use Scenario: Replacing obsolete 74LS244 in aging test fixtures requiring TTL-compatible inputs and CMOS-level outputs. IC Role / Device Role / Timing Role: Pin-compatible drop-in replacement providing higher drive strength and lower static current than LS logic. Use Value: Eliminates need for external pullups or level shifters while improving signal integrity on long PCB traces (>15 cm). | Use Scenario: Conditioning digital stimulus signals from FPGA-based pattern generators before routing to DUT inputs. IC Role / Device Role / Timing Role: Output buffer with controlled edge rates (20 ns/V input slew) and 3-state capability for multiplexed signal routing. Use Value: Prevents signal reflections on 50-Ω coaxial paths by matching source impedance and enabling clean signal gating during test sequence transitions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal 3-state buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AHCT244NSR | Same AHCT family, identical electrical specs, but dual 4-bit noninverting buffers with separate OE per group (OE1A/OE1B, OE2A/OE2B) | Offers finer-grained 4-bit enable control vs. SN74AHCT540NSR's 4+4 grouping - better for asymmetric bus partitioning | Select SN74AHCT244NSR when independent control of two 4-bit sub-buses is required; otherwise SN74AHCT540NSR provides simpler layout with shared OE logic |
| 74LVC244APW | 3.3-V only (1.65–3.6 V), lower drive (±24 mA), smaller TSSOP-20 package (6.5 × 6.4 mm), 3.5 ns typical tPD | Not 5-V compatible; requires level translation when interfacing with 5-V systems - unsuitable for direct SN74AHCT540NSR replacement | Choose 74LVC244APW only in new 3.3-V designs prioritizing speed and density; avoid in mixed-voltage or legacy 5-V upgrades |
Compared with SN74AHCT244NSR and 74LVC244APW, the SN74AHCT540NSR uniquely balances 5-V TTL compatibility, dual-OE flexibility, and SOP-20 manufacturability - making it optimal for industrial control retrofits where voltage alignment and board space are constrained.
Availability
SN74AHCT540NSR is available at Aetrix Electronics and suitable for industrial automation, test equipment, and legacy system upgrades requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.
Supply support for SN74AHCT540NSR 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 for industrial, automotive, and communications markets.
The SN74AHCT540NSR belongs to TI's advanced high-speed CMOS (AHCT) logic family, engineered for seamless 5-V TTL-to-CMOS interfacing in mission-critical industrial control and instrumentation systems.
FAQ
What is the maximum operating temperature range for the SN74AHCT540NSR?
The SN74AHCT540NSR is rated for operation from –40°C to +125°C ambient temperature. This extended range is validated per TI's industrial qualification standards and supports deployment in harsh environments such as motor drives, factory automation controllers, and outdoor telecom infrastructure where thermal cycling and sustained high-temperature operation occur. The SN74AHCT540NSR maintains specified VOH/VOL and timing parameters across this full range.
Does the SN74AHCT540NSR require external pull-up resistors on its OE pins?
Yes - to ensure predictable high-impedance state during power-up or brownout conditions, both OE1 and OE2 pins of the SN74AHCT540NSR should be tied to VCC through pull-up resistors. TI recommends values between 4.7 kΩ and 10 kΩ, selected based on the driving source's current-sinking capability. Leaving OE pins floating risks undefined output states and potential bus contention in multi-driver systems.
Can the SN74AHCT540NSR drive a 50-pF load while maintaining its specified propagation delay?
Yes - the SN74AHCT540NSR's switching characteristics table specifies tPLH/tPHL = 6.0 ns (typical) and 10 ns (max) at CL = 50 pF and VCC = 5 V. This confirms reliable operation into heavier capacitive loads common in backplane routing or multi-drop bus configurations. For best results, maintain short trace lengths and minimize stubs to avoid exceeding the 50-pF design target.
Is the SN74AHCT540NSR pin-compatible with the obsolete SN74LS244N?
No - although both are octal 3-state buffers, the SN74AHCT540NSR uses a different pinout: OE1/OE2 are on pins 1/19, while SN74LS244N places OE on pins 1/19 but with inverted logic (active-high). Additionally, SN74AHCT540NSR has inputs on pins 2–9 and outputs on 11–18, whereas SN74LS244N maps inputs to 2–5/11–14 and outputs to 3–6/12–15. Direct replacement requires PCB redesign or adapter circuitry.
What is the recommended bypass capacitor value for the VCC pin of the SN74AHCT540NSR?
Texas Instruments recommends a 0.1 µF ceramic capacitor placed as close as possible (<5 mm) to the VCC pin (pin 20) of the SN74AHCT540NSR. For systems with multiple logic devices sharing the same 5-V rail, adding a bulk 1 µF–10 µF tantalum or aluminum electrolytic capacitor nearby improves low-frequency noise suppression. The 0.1 µF cap must be X7R or better dielectric with low ESL to effectively filter high-frequency switching transients generated by the SN74AHCT540NSR's 8-mA output transitions.
SN74AHCT540NSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHCT
- 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:
- 8mA, 8mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SO
SN74AHCT540NSR FAQ
1.How can I place an order for SN74AHCT540NSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHCT540NSR 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 SN74AHCT540NSR reliable?
The price and inventory of SN74AHCT540NSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHCT540NSR is usually 5 days.
3.What payment methods are accepted for SN74AHCT540NSR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHCT540NSR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AHCT540NSR?
SN74AHCT540NSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHCT540NSR 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 SN74AHCT540NSR?
For technical support, including SN74AHCT540NSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHCT540NSR requirements.
6.How does Aetrix verify that SN74AHCT540NSR is sourced from the original manufacturer or authorized distributors?
All SN74AHCT540NSR 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 SN74AHCT540NSR meets industry standards.
7.What is the process for return or replacement of SN74AHCT540NSR?
All SN74AHCT540NSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHCT540NSR, 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 SN74AHCT540NSR part is unused and in its original packaging.
Return procedure for SN74AHCT540NSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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