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Texas Instruments SN74HC240NSR
- Part No.:
- SN74HC240NSR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74HC240NSR.pdf
- Description:
- IC BUFFER INVERT 6V 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:4,052
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Product details
Overview
SN74HC240NSR from Texas Instruments is an octal inverting buffer/line driver with 3-state outputs, designed for memory address and bus driving in industrial control and embedded systems. It operates from 2V to 6V, delivers ±6mA output drive at 5V, exhibits typical propagation delay of 9ns, and consumes ≤80µA ICC - enabling low-power, high-density bus interfacing.
For engineers reviewing the SN74HC240NSR datasheet, SN74HC240NSR pinout, SN74HC240NSR application, or SN74HC240NSR equivalent, this page provides verified functional mode behavior, thermal metrics for SOP-20 package, switching characteristics at 50pF/150pF loads, and validated alternatives for 3-state logic bus buffering.
Technical Context
The SN74HC240NSR implements two independent 4-bit inverting buffers, each controlled by a dedicated output-enable (OE) input. When OE is low, inverted data passes from A inputs to Y outputs; when OE is high, all eight outputs enter high-impedance state - supporting bidirectional bus arbitration and memory address latching.
Its CMOS HC-family architecture ensures compatibility with LSTTL loads (up to 15), low input current (≤1µA), and rail-to-rail output swing. The device is specified for –40°C to +85°C operation and supports 3.3V and 5V system interfaces without level translation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 2V to 6V - enables direct interface with 3.3V and 5V logic domains without voltage translation. |
| Output Drive Capability | ±6mA at 5V - sufficient to drive 15 LSTTL loads, supporting legacy TTL-compatible bus loading. |
| Propagation Delay (tpd) | 9ns typical at VCC = 4.5V, CL = 50pF - ensures timing-critical address/data path integrity in microcontroller peripheral buses. |
| Quiescent Current (ICC) | ≤80µA max at 6V - minimizes standby power in battery-backed or energy-sensitive industrial controllers. |
| Input Leakage Current | ≤1µA max - prevents unintended logic transitions on unterminated or high-impedance control lines. |
| 3-State Enable/Disable Time | ten = 25ns, tdis = 32ns max at 6V - guarantees clean bus release and acquisition during multiplexed memory access cycles. |
Pinout & Package
SOP-20 (NS) package: 12.6mm × 7.8mm body size, 12.6mm × 5.3mm footprint, surface-mount, RoHS-compliant, moisture sensitivity level 1, peak reflow 260°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1OE, 19OE | Active-low output enable inputs | Independently control 4-bit groups; low enables inverted A→Y transfer, high forces high-Z - essential for bus contention avoidance. |
| 2A1–8A4, 11A1–17A4 | Buffer input terminals | Eight logic inputs grouped into two 4-bit sets; accept standard CMOS/TTL voltage levels across full 2V–6V supply range. |
| 3Y4–9Y1, 12Y4–18Y1 | Inverting 3-state outputs | Eight buffered, inverted outputs; sink/source ±6mA; high-Z state isolates bus segments during idle or arbitration phases. |
| 10GND, 20VCC | Power supply terminals | Dedicated ground and supply pins minimize switching noise coupling; require local 0.1µF bypass capacitor per VCC pin. |
Key Features
| Feature | Design Value |
|---|---|
| Inverting 3-state buffer architecture | Enables bidirectional bus control and memory address latching without external inverters or tri-state logic gates. |
| Wide 2V–6V supply range | Supports mixed-voltage system integration - e.g., 3.3V MCU interfacing to 5V peripheral address/data buses. |
| Low 80µA max ICC | Reduces system-level quiescent power in always-on industrial I/O modules and programmable logic controllers. |
| 9ns typical tpd at 4.5V | Maintains timing margins in 20–25MHz address strobe applications, such as SRAM or FPGA configuration memory access. |
| ±6mA output drive | Drives standard LSTTL loads directly - eliminates need for discrete buffer stages in legacy backplane or ISA-style bus designs. |
Applications
| Industrial PLC Backplane Interface | Microcontroller Memory Address Buffering |
|---|---|
Use Scenario: Isolating and driving 16-bit address bus between CPU and multiple I/O expansion modules in modular PLC chassis. IC Role / Device Role / Timing Role: Inverting 3-state buffer providing address signal integrity, bus contention management, and load matching across 20cm backplane traces. Use Value: Enables deterministic address decoding with <9ns skew across all 8 bits, while high-Z state prevents signal corruption during module hot-swap events. | Use Scenario: Buffering 8-bit address lines from an ARM Cortex-M4 to external SPI flash or parallel EEPROM in space-constrained edge sensor nodes. IC Role / Device Role / Timing Role: Level-shifting and fanout buffer for memory-mapped peripherals operating at 3.3V supply with 5V-tolerant address latching requirements. Use Value: Eliminates need for discrete level translators; 2V–6V operation allows direct connection to both 3.3V MCU I/O and 5V memory VCC domains. |
| Legacy Instrumentation Bus Driver | Programmable Logic Control Panel Interface |
Use Scenario: Driving 8-bit data bus between FPGA-based controller and vintage GPIB or IEEE-488 peripheral cards requiring LSTTL-compatible drive strength. IC Role / Device Role / Timing Role: High-current inverting line driver ensuring signal rise/fall times <15ns under 15 LSTTL load conditions. Use Value: Meets GPIB timing spec for data setup/hold without added RC networks; ±6mA drive sustains signal integrity over 30cm ribbon cable runs. | Use Scenario: Interfacing pushbutton matrix and LED status indicators to a PIC18F microcontroller in HVAC control panels with EMI-prone 24VAC environments. IC Role / Device Role / Timing Role: Isolated input conditioning and output buffering stage decoupling noisy 24VAC field wiring from sensitive MCU GPIOs. Use Value: 1µA max input leakage prevents false triggering from capacitive coupling; 3-state outputs allow shared LED driver bus with dynamic scan control. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting 3-state buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT240NSR | TTL-input thresholds (VIH = 2.0V min), identical pinout and drive capability | Better noise immunity in mixed 5V TTL/CMOS systems; not suitable for 2V–3.3V-only operation | Select when interfacing legacy 5V TTL logic with guaranteed VIH/VIL margins; avoid for sub-3.3V supply rails. |
| 74LCX240MTCX | Lower VCC range (2.0V–3.6V), higher speed (tpd = 5.5ns typ), different SOP-20 footprint (7.5mm × 4.4mm) | Optimized for 3.3V-only portable/embedded systems; incompatible with 5V bus domains | Choose for ultra-low-power, high-speed 3.3V applications where 5V tolerance is unnecessary and board space is constrained. |
Compared with SN74HC240NSR, SN74HCT240NSR offers superior noise margin in 5V TTL environments but sacrifices 2V operation; 74LCX240MTCX delivers faster switching and lower static power at 3.3V but lacks 5V compatibility and requires PCB layout revision due to smaller body size.
Availability
SN74HC240NSR is available at Aetrix Electronics and suitable for industrial PLC backplanes, microcontroller memory expansion, legacy instrumentation bus interfaces, and programmable logic control panel designs requiring stable component supply and long-term lifecycle support.
Supply support for SN74HC240NSR 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 ICs, with decades of heritage in industry-standard logic families.
The SN74HC240NSR belongs to TI's 74HC high-speed CMOS logic product line, engineered for reliable 3-state bus interfacing in industrial automation, test equipment, and legacy system upgrades where robustness and wide supply range are critical.
FAQ
What is the maximum operating temperature for SN74HC240NSR?
The SN74HC240NSR is rated for operation from –40°C to +85°C ambient temperature. This industrial-grade temperature range ensures reliable performance in programmable logic controllers, factory automation hardware, and outdoor-rated instrumentation enclosures without derating. Thermal metrics including RθJA = 113.4°C/W confirm adequate heat dissipation in standard FR-4 PCB layouts with 2oz copper.
Does SN74HC240NSR support 3.3V logic levels?
Yes, SN74HC240NSR fully supports 3.3V operation: its 2V–6V supply range includes 3.3V nominal, and input thresholds scale with VCC (VIH ≈ 0.7×VCC, VIL ≈ 0.3×VCC). At 3.3V, it delivers ≥4.5mA drive and maintains <12ns propagation delay - making SN74HC240NSR suitable for mixed-voltage MCU peripheral interfaces without level shifters.
How does the 3-state enable function work on SN74HC240NSR?
SN74HC240NSR has two independent active-low output-enable inputs (1OE on Pin 1, 2OE on Pin 19). When either OE is low, its corresponding 4-bit group (e.g., 1A1–1A4 → 1Y1–1Y4) passes inverted data; when high, those four outputs enter high-impedance state. This dual-OE architecture allows selective bus segment isolation - critical for multi-master memory or I/O expansion schemes.
Can SN74HC240NSR drive standard TTL loads?
Yes, SN74HC240NSR is explicitly characterized to drive up to 15 LSTTL loads per output, meeting legacy TTL fanout requirements. Its ±6mA output drive at 5V exceeds the 0.4mA sink / 0.04mA source needed for standard TTL, and its output voltage specs (VOH ≥ 4.4V, VOL ≤ 0.26V at 6mA) ensure noise margins >0.4V - validating direct interface with 74LS and 74ALS families.
What is the recommended bypass capacitor for SN74HC240NSR?
Texas Instruments recommends a 0.1µF ceramic capacitor placed as close as possible to the VCC (Pin 20) and GND (Pin 10) pins of SN74HC240NSR. For systems with high-frequency noise or multiple switching devices, paralleling a 1µF capacitor improves low-frequency decoupling. This minimizes supply rail disturbance during output transitions and ensures stable 3-state control timing per the device's switching characteristics table.
SN74HC240NSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HC
- Package/Case:
- 20-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- 7.8mA, 7.8mA
- Voltage - Supply:
- 2V ~ 6V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SO
SN74HC240NSR FAQ
1.How can I place an order for SN74HC240NSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HC240NSR 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 SN74HC240NSR reliable?
The price and inventory of SN74HC240NSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HC240NSR is usually 5 days.
3.What payment methods are accepted for SN74HC240NSR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HC240NSR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HC240NSR?
SN74HC240NSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HC240NSR 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 SN74HC240NSR?
For technical support, including SN74HC240NSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HC240NSR requirements.
6.How does Aetrix verify that SN74HC240NSR is sourced from the original manufacturer or authorized distributors?
All SN74HC240NSR 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 SN74HC240NSR meets industry standards.
7.What is the process for return or replacement of SN74HC240NSR?
All SN74HC240NSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74HC240NSR, 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 SN74HC240NSR part is unused and in its original packaging.
Return procedure for SN74HC240NSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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