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Texas Instruments SN74HCT240NE4
- Part No.:
- SN74HCT240NE4
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74HCT240NE4.pdf
- Description:
- IC INVERTER DUAL 4-INPUT 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,018
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Product details
Overview
SN74HCT240NE4 from Texas Instruments is an octal inverting buffer/line driver with 3-state outputs, designed for memory address and bus driving in 5V TTL-compatible systems. It operates from 4.5V to 5.5V, delivers ±6mA output drive, exhibits 12ns typical propagation delay, and draws ≤80μA quiescent current. It is used in industrial control backplanes and legacy microprocessor address latching.
For engineers reviewing the SN74HCT240NE4 datasheet, SN74HCT240NE4 pinout, SN74HCT240NE4 application, or SN74HCT240NE4 equivalent, key selection criteria include its dual 4-bit inverted 3-state architecture, TTL-input compatibility, high-current bus-driving capability, and PDIP-20 package suitability for through-hole prototyping and legacy board replacement.
Technical Context
The SN74HCT240NE4 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 - enabling bidirectional bus sharing without external logic.
Its HCT logic family ensures CMOS power efficiency with TTL voltage-level input thresholds (VIH = 2.0V min, VIL = 0.8V max), allowing direct interfacing with legacy 74LS and 74F devices while maintaining low ICC (≤80μA) and robust noise immunity (≥0.4V DC noise margin at VCC = 5V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5V–5.5V - compatible with standard 5V logic rails and tolerant of ±5% regulation variation |
| Propagation Delay | 12ns typical (CL = 50pF, VCC = 5.5V) - supports 30+ MHz bus toggle rates in address/data path applications |
| Output Drive | ±6mA at 5V - drives up to 15 LSTTL loads directly, eliminating need for external bus transceivers |
| Input Compatibility | TTL-voltage level (VIH ≥ 2.0V, VIL ≤ 0.8V) - interoperable with 74LS, 74F, and other bipolar logic families |
| Quiescent Current | ≤80μA max - enables low-power operation in always-on control logic and standby-bus keeper circuits |
| 3-State Enable Time | 19ns typical (ten, CL = 50pF, VCC = 5.5V) - ensures fast bus arbitration and minimal contention window during enable transitions |
| Input Leakage | ≤1μA max - prevents unintended logic switching on unterminated or high-impedance control lines |
Pinout & Package
SN74HCT240NE4 is supplied in a 20-pin plastic dual in-line package (PDIP), 24.33mm × 9.4mm body size, with 0.1-inch lead pitch and through-hole mounting. The package includes internal ground/power planes optimized for noise suppression in mixed-signal industrial environments.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1OE, 19 | Input | Active-low enable for first 4-bit inverting buffer (controls Y1–Y4) |
| 1A1–1A4, 2–4,8 | Input | Inverting data inputs for first buffer group (driven to Y1–Y4) |
| 1Y1–1Y4, 12,14,16,18 | Output | Inverted outputs of first buffer group (high-impedance when 1OE = high) |
| 2OE, 1 | Input | Active-low enable for second 4-bit inverting buffer (controls Y5–Y8) |
| 2A1–2A4, 11,13,15,17 | Input | Inverting data inputs for second buffer group (driven to Y5–Y8) |
| 2Y1–2Y4, 3,5,7,9 | Output | Inverted outputs of second buffer group (high-impedance when 2OE = high) |
| VCC, 20 | Power | +5V supply connection - requires local 0.1μF ceramic bypass capacitor |
| GND, 10 | Ground | Circuit reference return - must be connected to low-impedance system ground plane |
Key Features
| Feature | Design Value |
|---|---|
| Inverting 3-state architecture | Dual independent 4-bit groups allow selective bus isolation and polarity inversion without external inverters |
| TTL-compatible inputs | Accepts standard 74LS logic thresholds, enabling drop-in replacement in legacy designs without level-shifting |
| High-output current drive | ±6mA per output sustains signal integrity across long PCB traces and multi-load buses |
| Low quiescent power | 80μA max ICC enables use in battery-backed or energy-constrained control subsystems |
| Robust ESD protection | Rated to ±20mA clamp current - withstands handling and board-level transient events per JEDEC JESD22-A114 |
Applications
| Memory Address Buffering | Industrial Backplane Interface |
|---|---|
Use Scenario: Driving 16-bit address bus between microcontroller and multiple SRAM/ROM chips in PLC mainboard. IC Role / Device Role / Timing Role: Inverting 3-state buffer isolating CPU address lines during DMA cycles and enabling memory chip select decoding. Use Value: Eliminates bus contention during memory access arbitration; 12ns tpd ensures setup/hold timing compliance with 8MHz Z80 or 68K derivatives. | Use Scenario: Interfacing field I/O modules to central controller via shared parallel backplane in factory automation rack. IC Role / Device Role / Timing Role: Bidirectional bus driver translating TTL-level signals across 30cm backplane traces with noise margin preservation. Use Value: ±6mA drive compensates for trace capacitance and contact resistance; PDIP package allows hot-swap module replacement without rework. |
| Legacy Microprocessor Support | Test Equipment Signal Conditioning |
Use Scenario: Replacing obsolete 74LS240 in vintage computer repair and retro-computing expansion cards. IC Role / Device Role / Timing Role: Pin-compatible 5V logic buffer providing identical functionality with lower power and improved noise immunity. Use Value: Direct substitution without PCB modification; 80μA ICC reduces thermal load in densely packed ISA-style slots. | Use Scenario: Level-shifting and fan-out buffering for digital stimulus signals in automated test equipment (ATE) pattern generators. IC Role / Device Role / Timing Role: Isolating FPGA I/O banks from DUT interface connectors while inverting control strobes for timing alignment. Use Value: Dual OE inputs permit synchronized enable/disable of stimulus and capture paths; 3-state outputs prevent signal corruption during test mode transitions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT240N | Same silicon, identical electrical specs, same PDIP-20 package but RoHS-compliant lead finish (NIPDAU) | No functional difference; suitable for new designs requiring RoHS compliance | Select SN74HCT240N for production builds requiring full RoHS certification; SN74HCT240NE4 remains valid for legacy-replacement and non-RoHS environments. |
| 74ACT240PC | Higher speed (tpd = 8.5ns typ), 5V-only supply, ACT family - no TTL input compatibility | Requires redesign of upstream drivers to meet ACT VIH/VIL; not drop-in for LS/F interfaces | Choose 74ACT240PC only when upgrading entire signal chain for >50MHz operation and full 5V CMOS compatibility is confirmed. |
Compared with SN74HCT240N and 74ACT240PC, SN74HCT240NE4 uniquely balances TTL interoperability, industrial temperature range (–40°C to +85°C), and proven reliability in long-lifecycle embedded systems - making it optimal for maintenance, repair, and legacy continuity programs where pin-and-function equivalence is mandatory.
Availability
SN74HCT240NE4 is available at Aetrix Electronics and suitable for industrial control backplanes, legacy microprocessor support, and test equipment signal conditioning requiring stable component supply over extended product lifecycles.
Supply support for SN74HCT240NE4 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 for industrial, automotive, and communications markets.
The SN74HCT240NE4 belongs to TI's 74HCT logic family, engineered for TTL-compatible interfacing in 5V systems where low power, noise immunity, and bus-driving capability are critical - particularly in industrial automation and legacy computing infrastructure.
FAQ
What is the operating temperature range for SN74HCT240NE4?
The SN74HCT240NE4 is rated for industrial operation from –40°C to +85°C. This range is validated per TI's recommended operating conditions and supports deployment in factory-floor controllers, outdoor instrumentation, and unregulated enclosure environments where ambient temperatures exceed commercial-grade limits. The PDIP package's thermal resistance (RθJA = 84.6°C/W) ensures safe junction temperatures under typical 5V/10mA load conditions.
Does SN74HCT240NE4 support non-inverting operation?
No, SN74HCT240NE4 provides only inverting logic function: Y = NOT(A) when enabled. It does not include non-inverting buffer sections or configuration pins for polarity reversal. For non-inverting 3-state buffering, designers must select SN74HCT244NE4 (octal non-inverting buffer) or cascade two SN74HCT240NE4 devices - though the latter adds propagation delay and increases board area.
Can SN74HCT240NE4 drive a 50pF bus load with guaranteed timing?
Yes, SN74HCT240NE4 specifies 12ns typical propagation delay (tpd) and 19ns typical enable time (ten) under CL = 50pF, VCC = 5.5V, TA = 25°C conditions. These values are production-tested and guaranteed across the full industrial temperature range per TI's switching characteristics table, ensuring reliable timing margin for 8–10MHz synchronous bus applications.
Is SN74HCT240NE4 pin-compatible with older 74LS240 devices?
Yes, SN74HCT240NE4 maintains identical pinout, function table, and DC electrical behavior (VIH/VIL, VOH/VOL) as 74LS240, enabling direct replacement in existing PCBs. Key advantages include lower ICC (80μA vs. 19mA), higher noise immunity, and improved output drive (±6mA vs. ±8mA sink, but with symmetrical source capability), making it a drop-in upgrade for reliability and power savings.
What decoupling capacitor value is recommended for SN74HCT240NE4?
Texas Instruments recommends a 0.1μF ceramic capacitor placed as close as possible to the VCC (pin 20) and GND (pin 10) pins of SN74HCT240NE4. This value is validated for noise suppression across the device's operating frequency range and complements the internal power distribution network. For systems with high di/dt transients, paralleling with a 1μF tantalum capacitor further stabilizes rail voltage during simultaneous output switching.
SN74HCT240NE4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HCT
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- 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:
- 6mA, 6mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
SN74HCT240NE4 FAQ
1.How can I place an order for SN74HCT240NE4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HCT240NE4 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 SN74HCT240NE4 reliable?
The price and inventory of SN74HCT240NE4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HCT240NE4 is usually 5 days.
3.What payment methods are accepted for SN74HCT240NE4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HCT240NE4 transactions.
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4.How is shipping managed for SN74HCT240NE4?
SN74HCT240NE4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HCT240NE4 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 SN74HCT240NE4?
For technical support, including SN74HCT240NE4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HCT240NE4 requirements.
6.How does Aetrix verify that SN74HCT240NE4 is sourced from the original manufacturer or authorized distributors?
All SN74HCT240NE4 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 SN74HCT240NE4 meets industry standards.
7.What is the process for return or replacement of SN74HCT240NE4?
All SN74HCT240NE4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74HCT240NE4, 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 SN74HCT240NE4 part is unused and in its original packaging.
Return procedure for SN74HCT240NE4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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