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Texas Instruments SN74AHC240N
- Part No.:
- SN74AHC240N
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74AHC240N.pdf
- Description:
- IC BUFFER INVERT 5.5V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:648
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Product details
Overview
SN74AHC240N from Texas Instruments is an octal 3-state buffer/driver IC designed for bus-oriented memory address, clock, and data line driving in industrial and consumer systems. It features dual 4-bit channels with independent output-enable controls, 5.5V-tolerant inputs, 8mA output drive at 5V, and 3.6ns typical propagation delay (5V, CL=15pF). It operates across –40°C to +85°C and is packaged in a 20-pin PDIP.
For engineers reviewing the SN74AHC240N datasheet, SN74AHC240N pinout, SN74AHC240N application, or SN74AHC240N equivalent, this page delivers verified functional architecture, real-world timing behavior under load, thermal resistance (RθJA = 69°C/W), latch-up immunity (>250mA), and precise 3-state control logic - all critical for bus isolation, level translation, and high-density PCB layout decisions.
Technical Context
The SN74AHC240N implements two independent 4-bit non-inverting buffer sections, each with dedicated active-low output-enable (1OE, 2OE) pins. Its CMOS AHC logic family ensures rail-to-rail output swing, low static current (4µA typical ICC), and balanced rise/fall times.
It supports mixed-voltage interfacing via 5.5V-tolerant inputs while operating from VCC = 2V–5.5V, enabling use between 3.3V logic domains and legacy 5V buses. Output disable transitions exhibit matched tPZH/tPLZ (4.7ns typ. at 5V), minimizing bus contention risk during state changes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 2V to 5.5V - enables interoperability across 2.5V, 3.3V, and 5V logic domains without level shifters |
| Propagation Delay | 3.6ns typ. (A→Y, 5V, CL=15pF) - supports reliable operation up to ~100MHz bus frequencies |
| Output Drive | ±8mA at 5V - sufficient to drive 10 LSTTL loads or multiple CMOS inputs on shared lines |
| Input Tolerance | 5.5V max input voltage - allows direct connection to 5V signals even when VCC = 3.3V |
| 3-State Leakage | ±0.25µA max (IOZ) - ensures minimal bus leakage during high-impedance mode, critical for multi-drop integrity |
| Latch-up Immunity | >250mA per JESD 17 - provides robustness against transient ground bounce or ESD-induced parasitic thyristor activation |
| Operating Temp | –40°C to +85°C - qualified for industrial ambient environments without derating |
Pinout & Package
SN74AHC240N uses a 20-pin plastic dual in-line package (PDIP-N), body size 25.40mm × 6.35mm, with through-hole mounting and standard 0.3-inch row spacing.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1OE, 2OE | Active-low output enable | Controls 4-bit group output state; tie high via pullup for power-up high-Z safety |
| 1A1–1A4, 2A1–2A4 | Buffer inputs | Non-inverting data inputs for respective 4-bit channels; 5.5V tolerant |
| 1Y1–1Y4, 2Y1–2Y4 | Buffer outputs | 3-state outputs with ±8mA drive; high-Z when OE = high |
| GND (Pin 10) | Ground reference | Primary return path for all I/O and supply currents; must be low-impedance |
| VCC (Pin 20) | Power supply | Single supply rail for logic core and outputs; requires local 0.1µF bypass capacitor |
Key Features
| Feature | Design Value |
|---|---|
| Low propagation delay | 3.6ns typical (5V, CL=15pF) enables tight timing margins in high-speed address/data buses |
| 5.5V-tolerant inputs | Accepts 5V signals while powered from 3.3V or 2.5V - eliminates external level translators |
| High noise immunity | VIH(D) = 3.5V / VIL(D) = 1.5V (5V supply) - rejects >1.5V of coupled noise on inputs |
| Controlled output transition | tsk(o) ≤ 1ns (5V, CL=50pF) - minimizes skew between parallel outputs during enable/disable |
| Robust thermal performance | RθJA = 69°C/W (PDIP) - supports continuous operation at full drive without heatsinking below 70°C ambient |
Applications
| Memory Address Buffering | Industrial PLC Backplane Interface |
|---|---|
Use Scenario: Driving 16-bit address lines from a microcontroller to multiple SRAM or flash devices on a shared bus. IC Role / Device Role / Timing Role: Non-inverting 3-state buffer isolating MCU address outputs; enables time-multiplexed access to multiple memory chips. Use Value: 8mA drive strength ensures signal integrity across 10cm traces; 3.6ns delay preserves setup/hold timing at 25MHz bus clocks. | Use Scenario: Interfacing a 3.3V FPGA I/O bank to legacy 5V fieldbus peripherals (e.g., Modbus RTU transceivers). IC Role / Device Role / Timing Role: Level-translating buffer with 5.5V-tolerant inputs and 3.3V-compatible outputs; provides bidirectional signal conditioning. Use Value: Eliminates discrete resistor-divider networks; ±250mA latch-up rating withstands industrial EMI transients. |
| Smartphone Baseband Power Sequencing | Network Switch Control Plane Isolation |
Use Scenario: Enabling/disabling voltage regulator enable signals during boot sequence in multi-rail smartphone PMIC subsystems. IC Role / Device Role / Timing Role: Glue logic buffer with independent OE controls - sequences power rails by gating EN signals to DC/DC converters. Use Value: Low ICC (4µA typ.) minimizes quiescent current in always-on domains; 2V min VCC supports brownout-safe sequencing. | Use Scenario: Isolating CPU-side management interfaces (I²C, GPIO) from noisy switch fabric ASICs in enterprise Ethernet switches. IC Role / Device Role / Timing Role: 3-state bus isolator preventing back-drive during ASIC reset or firmware update. Use Value: High-Z leakage <0.25µA prevents false triggering; RθJA = 69°C/W sustains reliability in 70°C chassis environments. |
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 |
|---|---|---|---|
| SN74LVC240APWR | Lower VCC range (1.65–3.6V); 24mA drive at 3.3V; smaller TSSOP-20 package | Better suited for 3.3V-only systems requiring higher drive; not 5.5V-input tolerant | Select when operating exclusively at 3.3V and board space is constrained |
| 74AHC240D,653 (Nexperia) | Identical AHC logic family; SOIC-20 package; same 5.5V input tolerance and timing specs | Drop-in replacement in SOIC footprint; differs only in marking and reel packaging | Choose for second-source assurance in surface-mount designs using SOIC |
Compared with SN74AHC240N, SN74LVC240APWR offers higher drive but sacrifices 5V-system compatibility, while 74AHC240D,653 matches functionality exactly in SOIC - making SN74AHC240N the optimal choice for through-hole prototyping, industrial repair, or legacy PDIP-based systems requiring 5V-tolerant buffering.
Availability
SN74AHC240N is available at Aetrix Electronics and suitable for industrial control, telecom infrastructure, and embedded instrumentation requiring stable component supply, long-term obsolescence management, and RoHS-compliant through-hole logic.
Supply support for SN74AHC240N 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 delivering analog, embedded processing, and logic solutions with over 90 years of innovation in industrial, automotive, and communications markets.
The SN74AHC240N belongs to TI's AHC logic family - engineered for high-speed, low-power, 3-state bus interface applications where signal integrity, voltage translation, and latch-up immunity are critical in dense PCB layouts.
FAQ
What is the maximum output current per pin for SN74AHC240N?
The SN74AHC240N supports ±8mA DC output current per Y pin at VCC = 5V, with absolute maximum ratings of ±25mA per output and ±75mA total device current. This allows reliable driving of 10 LSTTL loads or multiple CMOS inputs without external buffering. Exceeding ±25mA risks permanent damage per Absolute Maximum Ratings.
Does SN74AHC240N support mixed-voltage operation?
Yes, SN74AHC240N supports mixed-voltage operation: its inputs tolerate up to 5.5V regardless of VCC (2V–5.5V), enabling direct interfacing between 5V legacy circuits and 3.3V or 2.5V logic domains without level shifters. Outputs swing rail-to-rail (0V to VCC), so output voltage is determined solely by the SN74AHC240N's supply rail.
How does SN74AHC240N behave during power-up?
During power-up, SN74AHC240N outputs default to high-impedance if OE pins are tied high (e.g., via pullup resistors to VCC), preventing bus contention. The device draws only 4µA typical ICC in quiescent state, and its 2V minimum VCC allows safe operation during brownout conditions. TI recommends pullup resistors on 1OE/2OE to ensure defined high-Z state before VCC stabilizes.
What is the thermal resistance (RθJA) of SN74AHC240N in its PDIP package?
The SN74AHC240N in PDIP (N) package has a junction-to-ambient thermal resistance (RθJA) of 69°C/W, measured under JEDEC JESD 51-7 conditions. This value assumes standard 2-layer PCB with 1 in² copper pour. At 8mA per output and 20mA total IOUT, self-heating remains below 2°C - eliminating need for heatsinking in most industrial applications.
Can SN74AHC240N replace older 74LS240 logic in existing designs?
SN74AHC240N can functionally replace 74LS240 in many cases due to identical pinout and 3-state buffer functionality, but key differences exist: SN74AHC240N draws far less current (4µA vs. ~20mA), has faster propagation (3.6ns vs. 15ns), and requires no external pullups on inputs. However, its CMOS inputs are high-impedance - unused inputs must be actively terminated to VCC or GND, unlike LS TTL's internal pull-downs.
SN74AHC240N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHC
- 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:
- 8mA, 8mA
- Voltage - Supply:
- 2V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
SN74AHC240N FAQ
1.How can I place an order for SN74AHC240N through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHC240N 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 SN74AHC240N reliable?
The price and inventory of SN74AHC240N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHC240N is usually 5 days.
3.What payment methods are accepted for SN74AHC240N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHC240N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AHC240N?
SN74AHC240N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHC240N 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 SN74AHC240N?
For technical support, including SN74AHC240N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHC240N requirements.
6.How does Aetrix verify that SN74AHC240N is sourced from the original manufacturer or authorized distributors?
All SN74AHC240N 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 SN74AHC240N meets industry standards.
7.What is the process for return or replacement of SN74AHC240N?
All SN74AHC240N units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHC240N, 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 SN74AHC240N part is unused and in its original packaging.
Return procedure for SN74AHC240N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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