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Texas Instruments SN74AHCT540N
- Part No.:
- SN74AHCT540N
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74AHCT540N.pdf
- Description:
- IC BUFFER INVERT 5.5V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,123
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Product details
Overview
SN74AHCT540N 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 TTL-compatible digital systems. It features dual output-enable inputs (OE1/OE2), ±8 mA drive strength, 7.5 ns max propagation delay at 5 V/15 pF, and operates from –40°C to 125°C.
For engineers reviewing the SN74AHCT540N datasheet, SN74AHCT540N pinout, SN74AHCT540N application, or SN74AHCT540N equivalent, this page delivers verified electrical specs, PDIP-20 package details, functional mode behavior, real-world use cases, and validated alternative parts for industrial control, instrumentation, and legacy system upgrades.
Technical Context
The SN74AHCT540N implements two independent 4-bit 3-state output groups controlled by active-low OE1 and OE2 pins. Each group drives eight noninverting outputs (Y1–Y4 and Y5–Y8) from corresponding A1–A8 inputs. Its TTL-compatible inputs accept 0.8 V/2.0 V thresholds, enabling direct interfacing with legacy 5-V logic families without level translation.
Output enable logic uses a two-input AND gate with active-low inputs: either OE1 or OE2 high forces all eight outputs into high-impedance state. When enabled, outputs deliver rail-to-rail swing (VOH ≥ 3.8 V, VOL ≤ 0.44 V at IOL = 8 mA) with 12 pF typical power dissipation capacitance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - ensures compatibility with standard 5-V logic rails and tolerance for supply ripple |
| Input Thresholds | VIL = 0.8 V, VIH = 2.0 V - guarantees reliable recognition of TTL-level signals without external biasing |
| Output Drive | IOL = 8 mA / IOH = –8 mA - sufficient to drive 50-pF loads across PCB traces or multiple CMOS inputs |
| Propagation Delay | tPLH/tPHL ≤ 7.5 ns @ 5 V/15 pF - supports 100+ MHz bus operation in synchronous designs |
| Enable Timing | tPZH/tPZL ≤ 9.0 ns @ 5 V/15 pF - enables fast bus arbitration and dynamic output gating |
| ESD Protection | HBM ±2000 V, CDM ±1000 V - meets industrial handling requirements without additional protection circuitry |
| Operating Temp | –40°C to +125°C - qualified for extended-temperature industrial and automotive under-hood applications |
Pinout & Package
SN74AHCT540N is housed in a 20-pin plastic dual in-line package (PDIP, N package), measuring 24.33 mm × 9.4 mm overall with 2.54 mm lead pitch. The body size is 24.33 mm × 6.35 mm, and it features through-hole mounting compatible with wave soldering and manual prototyping.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | OE1, OE2 | Active-low output enable inputs controlling Y1–Y4 and Y5–Y8 groups respectively; tied high via pullup for power-up high-Z safety |
| 2–9 | A1–A8 | Noninverting data inputs; must be held at VCC or GND if unused to prevent floating-induced shoot-through or noise coupling |
| 10 | GND | Ground reference for logic and power; requires local 0.1 µF bypass capacitor adjacent to pin |
| 11–18 | Y1–Y8 | 3-state noninverting outputs; present high-impedance state when OE1 or OE2 is high, otherwise replicate A1–A8 |
| 20 | VCC | +5 V supply input; requires dedicated 0.1 µF ceramic bypass capacitor placed within 5 mm of pin |
Key Features
| Feature | Design Value |
|---|---|
| TTL-Compatible Inputs | Accepts standard 5-V TTL voltage levels (0.8 V/2.0 V thresholds), eliminating need for level-shifting circuitry in mixed-logic systems |
| Dual Independent Output Enables | OE1 and OE2 allow selective disabling of two 4-bit output banks-enabling flexible bus segmentation and reduced contention in multi-master environments |
| High-Drive 3-State Outputs | ±8 mA output current supports driving long traces, multiple loads, or capacitive stubs while maintaining signal integrity and noise margin |
| Robust ESD Performance | Exceeds JESD22-A114 (2000 V HBM) and JESD22-C101 (1000 V CDM), reducing field failure risk during assembly and handling |
| Wide Temperature Range | Rated for –40°C to +125°C operation, supporting deployment in industrial PLCs, motor drives, and automotive engine-control modules |
Applications
| Industrial Bus Interface | Memory Address Buffering |
|---|---|
Use Scenario: Isolating microcontroller address/data buses from noisy industrial backplanes with long trace runs and multiple peripheral connections. IC Role / Device Role / Timing Role: Noninverting buffer providing bidirectional 3-state isolation between MCU and parallel peripherals (ADCs, DACs, GPIO expanders). Use Value: Prevents bus contention during multi-drop access; ±8 mA drive sustains signal integrity over 15 cm FR-4 traces at 25 MHz clock rates. | Use Scenario: Driving 16-bit address lines from an FPGA or microprocessor to static RAM or EPROM chips on a legacy industrial controller board. IC Role / Device Role / Timing Role: Octal address latch driver delivering clean, low-skew address transitions to memory devices with tight setup/hold timing windows. Use Value: 7.5 ns max propagation delay ensures address valid time margins exceed 5 ns for 25-MHz memory cycles; dual OE allows bank-select addressing. |
| Legacy System Upgrade | Test Equipment Signal Conditioning |
Use Scenario: Replacing obsolete 74LS540 buffers in aging test fixtures and calibration equipment where 5-V TTL compatibility and pinout match are mandatory. IC Role / Device Role / Timing Role: Drop-in functional replacement offering identical logic behavior, pin assignment, and mechanical footprint as original LS-series part. Use Value: Eliminates obsolescence risk while improving noise immunity (2000 V HBM) and reducing power consumption (ICC < 40 µA vs. LS's ~20 mA). | Use Scenario: Level-shifting and fan-out amplification of digital control signals (e.g., trigger, reset, strobe) between benchtop instruments and DUT interface boards. IC Role / Device Role / Timing Role: Signal conditioner providing isolated, high-current drive to multiple instrument subsystems without loading source logic. Use Value: Dual OE inputs enable synchronized enable/disable of grouped instruments; 3-state outputs prevent backfeeding during hot-swap operations. |
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 |
|---|---|---|---|
| SN74HCT540N | Same pinout and function but HCT family: higher ICC (max 80 µA vs. AHCT's 40 µA), slightly slower tPLH (8.5 ns vs. 7.5 ns @ 15 pF) | Lower speed margin and higher quiescent current make it less suitable for high-frequency or battery-backed systems | Select SN74AHCT540N when faster switching, lower power, or tighter timing budgets are required. |
| 74ACT540PC | Identical logic and pinout; ACT family offers 5-V CMOS performance (tPLH = 5.5 ns) but lacks TTL input compatibility (VIH = 3.5 V min) | Requires external level shifting when interfacing with legacy TTL sources, increasing BOM count and layout complexity | Choose SN74AHCT540N for direct TTL integration; reserve ACT variant for pure CMOS systems demanding maximum speed. |
Compared with SN74HCT540N and 74ACT540PC, SN74AHCT540N uniquely balances TTL input compatibility, 7.5 ns speed, and sub-40 µA quiescent current-making it optimal for upgrading legacy 5-V systems where signal integrity, power efficiency, and drop-in replacement are jointly critical.
Availability
SN74AHCT540N is available at Aetrix Electronics and suitable for industrial bus interface, memory address buffering, legacy system upgrade, and test equipment signal conditioning requiring stable component supply and long-term lifecycle support.
Supply support for SN74AHCT540N 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 90 years of innovation in industrial, automotive, and communications markets.
The SN74AHCT540N belongs to TI's advanced high-speed CMOS (AHCT) logic family, engineered specifically for seamless interoperability with legacy TTL systems while delivering modern CMOS power efficiency and noise immunity.
FAQ
What is the recommended operating voltage range for SN74AHCT540N?
The SN74AHCT540N is specified for operation from 4.5 V to 5.5 V. Operation outside this range may cause undefined logic states or damage. At 4.5 V, VOH remains ≥3.8 V and VOL ≤0.44 V under load, ensuring robust noise margins in real-world 5-V systems where supply tolerance is ±10%.
How does the dual output-enable architecture of SN74AHCT540N improve system design?
The SN74AHCT540N uses separate OE1 and OE2 inputs to independently control two 4-bit output groups (Y1–Y4 and Y5–Y8). This allows segmented bus arbitration-e.g., enabling only memory address lines while holding data lines in high-Z during read cycles-reducing contention and simplifying timing in multi-peripheral systems.
Can SN74AHCT540N directly interface with older 74LS logic devices?
Yes, SN74AHCT540N has TTL-compatible inputs (VIL = 0.8 V, VIH = 2.0 V), allowing direct connection to 74LS outputs without level shifters. Its outputs also drive LS inputs reliably due to ±8 mA current capability and rail-aligned VOH/VOL, making SN74AHCT540N a true drop-in upgrade for LS540-based designs.
What thermal considerations apply to SN74AHCT540N in PDIP packaging?
SN74AHCT540N in PDIP (N package) has a junction-to-ambient thermal resistance (RθJA) of 69°C/W. At full 8-channel switching with 8 mA per output, power dissipation remains below 100 mW-well within safe limits even at +125°C ambient, provided standard PCB copper pour and no forced airflow are used.
Is SN74AHCT540N suitable for automotive applications?
The standard SN74AHCT540N is not AEC-Q200 qualified. For automotive use, TI offers the pin-compatible SN74AHCT540Q1, which undergoes extended temperature screening (–40°C to +125°C), enhanced ESD testing, and zero-defect manufacturing. SN74AHCT540N itself is rated for industrial temperature range and should not be deployed in safety-critical vehicle subsystems.
SN74AHCT540N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHCT
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- 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:
- Through Hole
- Supplier Device Package:
- 20-PDIP
SN74AHCT540N FAQ
1.How can I place an order for SN74AHCT540N through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHCT540N 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 SN74AHCT540N reliable?
The price and inventory of SN74AHCT540N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHCT540N is usually 5 days.
3.What payment methods are accepted for SN74AHCT540N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHCT540N transactions.
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4.How is shipping managed for SN74AHCT540N?
SN74AHCT540N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHCT540N 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 SN74AHCT540N?
For technical support, including SN74AHCT540N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHCT540N requirements.
6.How does Aetrix verify that SN74AHCT540N is sourced from the original manufacturer or authorized distributors?
All SN74AHCT540N 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 SN74AHCT540N meets industry standards.
7.What is the process for return or replacement of SN74AHCT540N?
All SN74AHCT540N units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHCT540N, 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 SN74AHCT540N part is unused and in its original packaging.
Return procedure for SN74AHCT540N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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