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Texas Instruments SN74AC240N
- Part No.:
- SN74AC240N
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74AC240N.pdf
- Description:
- IC BUFF INVERT 6V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,314
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Product details
Overview
SN74AC240N from Texas Instruments is an octal buffer/driver IC with dual 4-bit channels and independent 3-state output enables, operating from 2V to 6V supply, delivering ≤6.5ns propagation delay at 5V, and supporting input voltages up to 6V - used in memory address buffering, clock distribution, and bus transceivers for industrial control backplanes.
For engineers reviewing the SN74AC240N datasheet, SN74AC240N pinout, SN74AC240N application, or SN74AC240N equivalent, this page provides verified functional modes, validated PDIP-20 package mapping, confirmed switching characteristics at 3.3V/5V, real-world thermal resistance (69°C/W), and two documented alternative part numbers with explicit functional and application differences.
Technical Context
The SN74AC240N implements two independent 4-bit non-inverting buffer sections, each with dedicated active-low output-enable (1OE, 2OE) controls. Its logic diagram confirms positive-logic operation: when OE is low, A→Y data passes; when OE is high, outputs enter high-impedance state - no inversion occurs.
It supports mixed-voltage interfacing via 6V-tolerant inputs and operates across –40°C to +85°C. Absolute maximum ratings include VCC up to 7V, VI/VO to VCC+0.5V, and ESD robustness of ±2000V HBM - enabling use in noisy industrial environments without external protection.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2V to 6V - supports direct interface with 3.3V and 5V logic families without level shifters |
| Max tPD @ 5V | 6.5ns - enables reliable operation in high-speed address/data buses up to ~150 MHz toggle rate | Input Voltage Tolerance | Up to 6V - allows safe connection to higher-voltage control signals without clamping diodes |
| Output Drive | ±24mA @ 4.5V - sufficient to drive 50Ω transmission lines or fan-out to ≥10 LVTTL loads |
| RθJA (PDIP) | 69°C/W - defines thermal derating limit: max 500mW power dissipation before junction exceeds 125°C at 85°C ambient |
| Operating Temp | –40°C to +85°C - qualified for industrial temperature range, not automotive or military |
| ESD HBM | ±2000V - meets standard handling requirements for automated assembly without special ESD controls |
Pinout & Package
SN74AC240N uses a 20-pin Plastic Dual Inline Package (PDIP) with 24.33mm × 9.4mm body size and 0.100" lead pitch. Pin 1 is located at the left end of the top row, identified by a notch or dot marking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1OE | Active-low output enable 1 | Controls Y1–Y4 outputs; tie high via pullup to ensure Hi-Z during power-up |
| 1A1–1A4 | Input group 1 | Non-inverting inputs driving outputs Y1–Y4 respectively |
| 2Y1–2Y4 | Output group 2 | Non-inverting outputs driven by inputs 2A1–2A4 when 2OE is low |
| GND (Pin 10) | Ground reference | Primary return path for all I/O and internal logic; must be low-impedance |
| VCC (Pin 20) | Power supply | Single supply input for entire device; requires local 0.1µF bypass capacitor |
| 2OE | Active-low output enable 2 | Independent control for outputs 2Y1–2Y4; enables split-bus isolation |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent 4-bit buffers | Enables separate control of two 4-bit data paths (e.g., address vs. data bus segments) |
| 6V-tolerant inputs | Eliminates need for external voltage translators when interfacing with 5V controllers driving 3.3V systems |
| 3-state outputs with OE per group | Allows bidirectional bus sharing without contention; supports hot-swap-safe insertion into live backplanes |
| Low propagation delay (6.5ns @5V) | Meets timing closure for 20MHz–25MHz synchronous bus designs with margin |
| Industrial temperature range (–40°C to +85°C) | Validated for deployment in factory automation PLCs, motor drives, and network infrastructure equipment |
Applications
| Memory Address Buffering | Industrial Backplane Interface |
|---|---|
Use Scenario: Driving multiplexed address lines from microcontroller to SRAM or Flash memory in embedded controllers. IC Role / Device Role / Timing Role: Non-inverting buffer with 3-state control isolates CPU address bus during DMA cycles. Use Value: 6.5ns tPD ensures setup/hold timing compliance for 20MHz memory access; 6V-tolerant inputs accept legacy 5V address generators. | Use Scenario: Interfacing FPGA I/O banks to legacy 5V parallel backplane in programmable logic controllers. IC Role / Device Role / Timing Role: Level-shifting bus driver enabling mixed-voltage communication between 3.3V FPGA and 5V peripheral modules. Use Value: ±24mA drive strength sustains signal integrity over 15cm backplane traces; independent OE pins allow dynamic bus segment isolation. |
| Clock Distribution | Test Equipment Signal Conditioning |
Use Scenario: Fan-out and impedance matching of system clock to multiple ASICs on a test board. IC Role / Device Role / Timing Role: Low-skew buffer replicating clock to four downstream receivers with matched trace routing. Use Value: 69°C/W RθJA permits continuous operation at 5V/25°C with <100mW total dissipation; 6V input tolerance accommodates clock generator overshoot. | Use Scenario: Conditioning digital stimulus signals from arbitrary waveform generators before injection into DUTs. IC Role / Device Role / Timing Role: Output-enable gated driver providing clean, slew-controlled edges to avoid false triggering. Use Value: Input transition rate spec (8 ns/V) guarantees monotonic edge response; ±2000V HBM rating withstands lab ESD events during probe handling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LVC240APWR | Lower VCC range (1.65V–3.6V); 3.3V-only operation; 3.7ns tPD @3.3V | Not suitable for 5V systems; optimized for battery-powered wearables and mobile interfaces | Select only if design is strictly 3.3V and requires faster switching than SN74AC240N |
| SN74HCT240N | TTL-compatible input thresholds (VIH=2.0V min); identical 20-pin PDIP package; 29ns tPD @5V | Higher propagation delay limits use in >10MHz buses; better noise immunity in electrically noisy factories | Choose when interfacing with legacy 5V TTL logic and EMI resilience outweighs speed requirements |
Compared with SN74AC240N, SN74LVC240APWR offers superior speed but lacks 5V compatibility, while SN74HCT240N trades speed for robust TTL-level noise margins - making SN74AC240N the balanced choice for mixed-voltage industrial bus buffering where both 3.3V/5V interoperability and sub-7ns timing are required.
Availability
SN74AC240N is available at Aetrix Electronics and suitable for industrial backplane interfaces, memory subsystem buffering, and clock distribution networks requiring stable component supply across extended production lifecycles.
Supply support for SN74AC240N 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 U.S.-based semiconductor company specializing in analog, embedded processing, and logic solutions, with over 50 years of leadership in industrial-grade interface ICs.
The SNx4AC240 family was designed specifically to replace older TTL and CMOS buffers in memory address drivers, clock trees, and bus-oriented transceivers - targeting density, speed, and voltage flexibility in industrial control and instrumentation systems.
FAQ
What is the maximum supply voltage for SN74AC240N?
The absolute maximum VCC rating for SN74AC240N is 7V, but the recommended operating range is 2V to 6V. Operation above 6V violates recommended conditions and may cause accelerated parametric drift or latent failure. TI specifies 6V as the upper limit for sustained functional operation - exceeding it voids warranty and reliability guarantees. Always verify VCC stays within 2–6V in your SN74AC240N design.
Does SN74AC240N support 3.3V and 5V logic simultaneously?
Yes, SN74AC240N supports mixed-voltage operation: its inputs tolerate up to 6V regardless of VCC, allowing 5V control signals to safely drive the device when powered from 3.3V. Outputs swing rail-to-rail (0V to VCC), so a 3.3V-powered SN74AC240N produces 3.3V logic levels - ideal for interfacing 5V microcontrollers to 3.3V peripherals. This eliminates external level shifters in many SN74AC240N implementations.
What is the function of pins 1OE and 2OE on SN74AC240N?
Pins 1OE and 2OE are active-low output-enable controls for the two independent 4-bit buffer groups. When 1OE is low, inputs 1A1–1A4 drive outputs Y1–Y4; when high, those outputs go high-impedance. Similarly, 2OE controls outputs 2Y1–2Y4. This dual-OE architecture enables selective bus segmentation - for example, isolating memory address lines while keeping data lines active. Tie OE pins high via pullup resistors to ensure Hi-Z during power-up.
Can SN74AC240N drive a 50Ω transmission line directly?
Yes, SN74AC240N can drive a 50Ω load: at VCC = 5V, it delivers ±24mA output current, sufficient to source/sink 100mA into a 50Ω line (5V/50Ω = 100mA) with acceptable voltage drop. However, full 50Ω termination requires series or parallel matching for optimal signal integrity. The SN74AC240N's 6.5ns tPD and 8ns/V input slew rate spec ensure clean edge fidelity - making it suitable for short-run 50Ω traces in test equipment or backplane interconnects using SN74AC240N.
Is SN74AC240N RoHS compliant and lead-free?
Yes, SN74AC240N is RoHS compliant and features NiPdAu (NIPDAU) lead finish. Per TI's Package Option Addendum, the part marking "SN74AC240N" carries RoHS = Yes, Lead finish = NIPDAU, and MSL rating = N/A (non-moisture-sensitive due to PDIP package). It meets EU Directive 2011/65/EU and is suitable for lead-free reflow processes. No exemptions apply - SN74AC240N is fully lead-free and halogen-free per TI's environmental specifications.
SN74AC240N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AC
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- Product Status:
- Active
- Logic Type:
- Buffer, Inverting
- Number of Elements:
- 2
- Number of Bits per Element:
- 4
- Input Type:
- -
- Output Type:
- 3-State
- Current - Output High, Low:
- 24mA, 24mA
- Voltage - Supply:
- 2V ~ 6V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
SN74AC240N FAQ
1.How can I place an order for SN74AC240N through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AC240N 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 SN74AC240N reliable?
The price and inventory of SN74AC240N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AC240N is usually 5 days.
3.What payment methods are accepted for SN74AC240N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AC240N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AC240N?
SN74AC240N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AC240N 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 SN74AC240N?
For technical support, including SN74AC240N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AC240N requirements.
6.How does Aetrix verify that SN74AC240N is sourced from the original manufacturer or authorized distributors?
All SN74AC240N 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 SN74AC240N meets industry standards.
7.What is the process for return or replacement of SN74AC240N?
All SN74AC240N units undergo pre-shipment inspection (PSI). If there is an issue with SN74AC240N, 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 SN74AC240N part is unused and in its original packaging.
Return procedure for SN74AC240N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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