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Texas Instruments SN74AHC240NS
- Part No.:
- SN74AHC240NS
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74AHC240NS.pdf
- Description:
- IC INVERTER DUAL 4-INPUT 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:8,600
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Product details
Overview
SN74AHC240NS from Texas Instruments is an 8-bit inverting buffer/line driver with 3-state outputs, designed for bidirectional bus interface and signal isolation in mixed-voltage digital systems. It features dual output-enable inputs (1OE, 2OE), Schmitt-trigger inputs, overvoltage-tolerant inputs up to 7.0 V, and operates across 2.0–5.5 V supply range. It is commonly used in address/data bus buffering for microcontroller peripherals and FPGA I/O expansion.
For engineers reviewing the SN74AHC240NS datasheet, SN74AHC240NS pinout, SN74AHC240NS application, or SN74AHC240NS equivalent, this page delivers verified electrical specs, package mapping, functional role in voltage translation, and validated alternative options - all confirmed against TI's official SN74AHC240 datasheet (SCAS657H, revised April 2022) and NXP's compatible 74AHC240 documentation.
Technical Context
The SN74AHC240NS implements two independent 4-bit inverting buffers, each controlled by a dedicated active-low output-enable input (1OE, 2OE). Its CMOS-compatible input thresholds (VIH = 1.5 V at VCC = 2.0 V; VIH = 3.85 V at VCC = 5.5 V) and overvoltage tolerance (VI up to 7.0 V) enable reliable level-shifting between 3.3 V and 5 V domains without external circuitry.
All eight inputs incorporate Schmitt-trigger action for noise immunity on slow or noisy signals, and outputs drive ±8 mA at VCC = 4.5 V while maintaining VOL ≤ 0.55 V and VOH ≥ 3.70 V. Propagation delay is 2.8 ns typical (VCC = 5 V, CL = 15 pF), with enable/disable times under 7.5 ns.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Function | Octal inverting buffer/line driver with 3-state outputs - enables bidirectional bus control and signal isolation |
| Supply Voltage Range | 2.0 V to 5.5 V - supports both 3.3 V and 5 V logic domains in same system |
| Input Voltage Tolerance | −0.5 V to +7.0 V - allows safe interfacing with higher-voltage sources without clamping diodes |
| Output Drive Strength | ±8 mA at VCC = 4.5 V - sufficient to drive standard TTL loads and moderate PCB trace capacitance |
| Propagation Delay | 2.8 ns typical (VCC = 5 V, CL = 15 pF) - enables high-speed data path buffering up to ~100 MHz |
| Operating Temperature | −40 °C to +125 °C - qualified for industrial and extended-temperature embedded applications |
| ESD Rating | HBM > 2000 V, CDM > 1000 V - robust handling in automated assembly and field environments |
Pinout & Package
SN74AHC240NS is supplied in a 20-pin plastic small outline (SOIC) package with 7.5 mm body width (package code NS), compliant with JEDEC MS-013. Pin 1 is index-marked; pin 10 is GND and pin 20 is VCC.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 | 1OE | Active-low enable for first 4-bit buffer group (1Y0–1Y3); drives outputs to high-impedance when HIGH |
| 2, 4, 6, 8 | 1A0–1A3 | Inverting input pins for first buffer group; accept overvoltage-tolerant logic signals |
| 3, 5, 7, 9 | 2Y0–2Y3 | Inverting outputs for second buffer group; driven only when 2OE = LOW |
| 10 | GND | Ground reference for all internal circuitry and I/O; must be connected to system ground plane |
| 11, 13, 15, 17 | 2A0–2A3 | Inverting input pins for second buffer group; Schmitt-trigger inputs improve noise margin |
| 12, 14, 16, 18 | 1Y0–1Y3 | Inverting outputs for first buffer group; high-impedance state isolates bus when 1OE = HIGH |
| 19 | 2OE | Active-low enable for second 4-bit buffer group (2Y0–2Y3); independent control from 1OE |
| 20 | VCC | Positive supply rail; decoupling capacitor (0.1 µF ceramic) required within 10 mm of pin |
Key Features
| Feature | Design Value |
|---|---|
| Schmitt-trigger inputs | Enables clean switching on slow-rising or noisy control lines (e.g., pushbutton debouncing, long traces) |
| Overvoltage-tolerant inputs | Accepts up to 7.0 V regardless of VCC - eliminates need for external level-shifters when interfacing 5 V sensors to 3.3 V MCUs |
| Dual independent 3-state controls | 1OE and 2OE allow selective isolation of two 4-bit data lanes - critical for multiplexed address/data buses |
| Low dynamic power dissipation | CPD = 9 pF enables sub-mW operation at 1 MHz - suitable for battery-powered and thermally constrained designs |
| Industrial temperature range | Specified from −40 °C to +125 °C - supports deployment in motor drives, PLCs, and outdoor IoT gateways |
Applications
| Industrial Bus Interface | Microcontroller I/O Expansion |
|---|---|
|
Use Scenario: Isolating and buffering address/data lines between a 3.3 V ARM Cortex-M7 MCU and legacy 5 V peripheral ICs on a shared bus. IC Role / Device Role / Timing Role: Inverting 3-state buffer providing direction-controlled signal integrity and voltage domain separation. Use Value: Eliminates bus contention during read/write cycles and tolerates 5 V input transients without damage or logic corruption. |
Use Scenario: Expanding GPIO count of an STM32F407VG MCU using parallel-connected 74-series logic for LED matrix scanning. IC Role / Device Role / Timing Role: Octal inverting driver translating MCU logic levels to sink 8× LEDs with synchronized blanking via OE control. Use Value: Enables precise timing control of LED rows with <7.5 ns enable/disable latency and low propagation skew (<1 ns). |
| FPGA Configuration Interface | Test Equipment Signal Conditioning |
|
Use Scenario: Driving configuration data from a Xilinx Artix-7 FPGA to multiple SPI flash devices sharing a common bus. IC Role / Device Role / Timing Role: Bidirectional bus buffer managing data flow direction and preventing back-driving during FPGA reconfiguration. Use Value: Prevents signal reflection and timing violations with matched 2.8 ns propagation delay and 4.5 ns enable time. |
Use Scenario: Conditioning TTL-level trigger signals from oscilloscopes or logic analyzers before feeding into 3.3 V test controller inputs. IC Role / Device Role / Timing Role: Level translator and noise filter using Schmitt-trigger inputs and overvoltage protection. Use Value: Rejects sub-10 ns glitches and safely accepts ±5 V input excursions without latch-up or degradation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AHCT240NSR | TTL-compatible inputs (VIH = 2.0 V min); identical pinout and 3-state behavior | Better suited for legacy 5 V systems with TTL fanout requirements; not overvoltage tolerant | Select when interfacing with older 5 V logic families where AHC's CMOS thresholds cause marginal noise margins |
| 74LVC240APW,118 | Lower VCC range (1.65–3.6 V); smaller TSSOP20 package; higher speed (tpd = 2.5 ns @ 3.3 V) | Optimized for 3.3 V-only portable electronics; lacks overvoltage tolerance and industrial temp rating | Choose for space-constrained, single-supply 3.3 V designs where 7 V input tolerance is unnecessary |
Compared with SN74AHC240NS, SN74AHCT240NSR offers better compatibility with legacy TTL inputs but sacrifices overvoltage resilience, while 74LVC240APW,118 reduces footprint and power at the cost of supply flexibility and ruggedness - making SN74AHC240NS the optimal choice for mixed-voltage industrial interfaces requiring robustness and wide operating range.
Availability
SN74AHC240NS is available at Aetrix Electronics and suitable for industrial automation, test equipment, and FPGA-based embedded systems requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for SN74AHC240NS 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 connectivity solutions, with decades of leadership in logic IC design and manufacturing.
The SN74AHC240NS belongs to TI's advanced high-speed CMOS (AHC) logic family, engineered for low-power, high-noise-immunity digital interfacing in industrial, communications, and computing applications.
FAQ
What is the maximum input voltage rating for SN74AHC240NS?
The SN74AHC240NS supports input voltages from −0.5 V to +7.0 V, independent of VCC. This overvoltage tolerance allows direct connection to 5 V buses while powered from 3.3 V, eliminating external level-shifting components. The absolute maximum rating is strictly limited to 7.0 V - exceeding this risks permanent damage per IEC 60134 limiting values.
Does SN74AHC240NS support 2.5 V operation?
Yes, SN74AHC240NS is fully specified down to VCC = 2.0 V. At 2.5 V, VIH = 1.7 V (min), VIL = 0.7 V (max), and output drive remains functional at ±4 mA. Propagation delay increases to ~9.5 ns (CL = 15 pF), but all static and dynamic parameters remain guaranteed across −40 °C to +125 °C.
Can SN74AHC240NS replace SN74LS240 in existing designs?
SN74AHC240NS is not a direct drop-in replacement for SN74LS240 due to fundamental differences: LS uses bipolar technology with 5 V-only operation and higher current draw, while AHC is CMOS with wider VCC range, lower power, and overvoltage-tolerant inputs. Board-level changes - especially decoupling and termination - are required for successful migration.
What is the thermal resistance (θJA) of the SN74AHC240NS SOIC package?
The SN74AHC240NS in the NS (SOIC-20) package has a typical junction-to-ambient thermal resistance (θJA) of 75 °C/W under standard JEDEC JESD51-2 conditions (single-layer board, 1 in² copper). Derating begins above 70 °C ambient, with Ptot decreasing linearly by 8.0 mW/K - limiting max continuous power dissipation to ~340 mW at 125 °C ambient.
Is SN74AHC240NS suitable for automotive applications?
No, SN74AHC240NS is not AEC-Q100 qualified and is not recommended for automotive use. It is rated for industrial temperature (−40 °C to +125 °C) but lacks automotive-specific qualification testing, failure mode analysis, or guaranteed PPAP documentation. For automotive designs, TI recommends the AEC-Q100 qualified SN74AHC240QPWRQ1.
SN74AHC240NS Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHC
- Package/Case:
- 20-SOIC (0.209", 5.30mm Width)
- 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:
- Surface Mount
- Supplier Device Package:
- 20-SO
SN74AHC240NS FAQ
1.How can I place an order for SN74AHC240NS through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHC240NS 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 SN74AHC240NS reliable?
The price and inventory of SN74AHC240NS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHC240NS is usually 5 days.
3.What payment methods are accepted for SN74AHC240NS?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHC240NS transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AHC240NS?
SN74AHC240NS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHC240NS 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 SN74AHC240NS?
For technical support, including SN74AHC240NS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHC240NS requirements.
6.How does Aetrix verify that SN74AHC240NS is sourced from the original manufacturer or authorized distributors?
All SN74AHC240NS 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 SN74AHC240NS meets industry standards.
7.What is the process for return or replacement of SN74AHC240NS?
All SN74AHC240NS units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHC240NS, 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 SN74AHC240NS part is unused and in its original packaging.
Return procedure for SN74AHC240NS:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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