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Texas Instruments SN74HCT240N
- Part No.:
- SN74HCT240N
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74HCT240N.pdf
- Description:
- IC BUFFER INVERT 5.5V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,920
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Product details
Overview
SN74HCT240N 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 supports high-density bus interfacing in industrial control and embedded data paths.
For engineers reviewing the SN74HCT240N datasheet, SN74HCT240N pinout, SN74HCT240N application, or SN74HCT240N equivalent, this page provides verified functional mode behavior, thermal resistance values for PDIP-20, 3-state timing parameters under 50pF load, and direct substitution guidance against industry-standard HCT-family alternatives.
Technical Context
The SN74HCT240N implements two independent 4-bit inverting buffers, each controlled by a dedicated output-enable (OE) input. When OE is low, inverted logic passes from A inputs to Y outputs; when OE is high, all eight outputs enter high-impedance state-enabling bidirectional bus sharing without external isolation.
Its HCT logic family ensures TTL-input voltage compatibility (VIH = 2V, VIL = 0.8V) while maintaining CMOS power efficiency. The device meets standard 5V digital system requirements with 80μA max ICC and 1μA max input current, supporting stable operation across –40°C to +85°C ambient.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5V–5.5V - Ensures robust operation across industrial 5V rail tolerances. |
| Propagation Delay | 12ns typical at 5V/50pF - Enables reliable timing in 25MHz+ address/data bus cycles. |
| Output Drive | ±6mA at 5V - Sufficient to drive 15 LSTTL loads directly without buffering. |
| Input Compatibility | TTL-voltage compatible (VIH ≥ 2V, VIL ≤ 0.8V) - Interoperates with legacy 74LS and microcontroller GPIOs. |
| Quiescent Current | 80μA max - Supports low-power standby modes in battery-backed systems. |
| 3-State Enable Time | 29ns max at 5.5V/50pF - Limits bus contention window during direction switching. |
| Thermal Resistance | RθJA = 84.6°C/W (PDIP-20) - Defines maximum power dissipation before junction overheating at 85°C ambient. |
Pinout & Package
SN74HCT240N uses a 20-pin plastic dual in-line package (PDIP), body size 24.33mm × 6.35mm, with through-hole mounting and standard 0.3-inch row spacing. Pin 1 is marked by a notch or dot; pin 10 is GND and pin 20 is VCC.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | Output Enable (1OE, 2OE) | Active-low enables respective 4-bit inverting buffer sections; high = high-Z output. |
| 2–4, 6–8, 11–13, 15–17 | Inputs (1A1–1A4, 2A1–2A4) | Eight TTL-compatible digital inputs; each drives corresponding inverted output. |
| 3, 5, 7, 9, 12, 14, 16, 18 | Outputs (1Y1–1Y4, 2Y1–2Y4) | Inverted buffered outputs; tri-state capable; sink/source up to ±6mA. |
| 10 | GND | Ground reference for logic and power; must be low-impedance connection. |
| 20 | VCC | Positive supply (4.5–5.5V); requires local 0.1μF bypass capacitor per device. |
Key Features
| Feature | Design Value |
|---|---|
| Inverting 3-State Buffers | Two independent 4-bit sections enable selective bus isolation without signal inversion conflict. |
| TTL-Compatible Inputs | Accepts standard LS-TTL logic thresholds, eliminating level-shifting in mixed-logic designs. |
| Low Power Consumption | 80μA max ICC allows integration into power-constrained subsystems without thermal derating. |
| High-Current Outputs | ±6mA drive capability supports direct fanout to multiple LSTTL inputs or LED indicators. |
| Controlled Switching | Specified tdis/ten/tt ensure predictable bus release timing and minimize glitches during state transitions. |
Applications
| Memory Address Buffering | Industrial Bus Transceiver |
|---|---|
Use Scenario: Driving 16-bit address lines from a microcontroller to SRAM or EPROM chips in a PLC backplane. IC Role / Device Role / Timing Role: Inverting 3-state buffer isolating CPU address bus from memory during DMA cycles. Use Value: Prevents bus contention via independent OE control; 12ns tpd maintains 25MHz address setup timing. | Use Scenario: Bidirectional data routing between two isolated CAN controller modules sharing a common RS-485 physical layer. IC Role / Device Role / Timing Role: Direction-controlled line driver enabling half-duplex bus arbitration with precise enable/disable timing. Use Value: ±6mA drive sustains signal integrity over 15m cable runs; 29ns ten ensures clean bus turnaround. |
| Legacy System Interface | Test Equipment Signal Conditioning |
Use Scenario: Adapting modern FPGA I/O banks to legacy 74LS-based peripheral cards in automated test fixtures. IC Role / Device Role / Timing Role: Level-translating inverting buffer matching LS input thresholds while sourcing adequate current. Use Value: TTL-compatible VIH/VIL eliminates external bias networks; PDIP-20 simplifies hand-soldered prototyping. | Use Scenario: Isolating and amplifying digital trigger signals in oscilloscope front-end logic before ADC sampling. IC Role / Device Role / Timing Role: Low-skew inverting buffer conditioning edge-sensitive strobes with minimal added jitter. Use Value: 12ns tpd and <1ns skew between channels preserve sub-40ns pulse fidelity for 25MHz sampling clocks. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT240DW | SOIC-20 package; RθJA = 109.1°C/W vs. 84.6°C/W for PDIP; identical electrical specs. | Suitable for surface-mount production; less thermal margin than PDIP in convection-cooled enclosures. | Select SN74HCT240DW for automated assembly where board space is constrained and airflow is assured. |
| 74HCT240N (Nexperia) | Same pinout and DC specs; tpd = 14ns typical (vs. 12ns); IOZ = ±5μA max (vs. ±10μA). | Valid drop-in replacement in non-critical timing paths; slightly higher off-state leakage may affect ultra-low-power sleep modes. | Choose 74HCT240N when sourcing diversification is required and 2ns tpd margin is acceptable. |
Compared with SN74HCT240DW and 74HCT240N, the SN74HCT240N offers superior thermal performance in through-hole layouts and tighter propagation delay, making it preferred for thermally demanding or timing-critical industrial control boards.
Availability
SN74HCT240N is available at Aetrix Electronics and suitable for industrial control panels, legacy system upgrades, and test equipment requiring stable component supply with long-term PDIP availability.
Supply support for SN74HCT240N 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 and embedded processing technologies, with over 50 years of leadership in logic IC design and manufacturing.
The SN74HCT240N belongs to TI's 74HCT logic family, engineered for TTL-compatible interfacing in industrial, automotive, and communications systems where reliability, noise immunity, and 5V operation are essential.
FAQ
What is the function of the two output-enable pins on the SN74HCT240N?
The SN74HCT240N has two independent output-enable inputs: 1OE (pin 1) controls the first four inverting buffers (1A1–1A4 → 1Y1–1Y4), and 2OE (pin 19) controls the second group (2A1–2A4 → 2Y1–2Y4). When either OE is low, its associated outputs pass inverted input data; when high, those outputs go high-impedance. This allows selective bus partitioning without disabling the entire device. The SN74HCT240N thus supports granular control in multi-segment memory or peripheral buses.
Does the SN74HCT240N require external pull-up resistors on its outputs?
No, the SN74HCT240N does not require external pull-up resistors on its outputs when used in standard 3-state bus applications. Its outputs actively drive both logic high and low states with ±6mA capability, and enter true high-impedance (not weak pull-up) when disabled. Pull-ups are only needed if open-drain emulation is required-functionality not supported by the SN74HCT240N's push-pull architecture.
Can the SN74HCT240N operate reliably at 4.5V supply voltage?
Yes, the SN74HCT240N is fully specified for operation from 4.5V to 5.5V. At 4.5V, its VOH remains ≥3.7V (with 6mA load) and VOL stays ≤0.33V, meeting TTL output thresholds. Propagation delay increases to 32ns max (vs. 29ns at 5.5V), but remains within system timing budgets for ≤20MHz bus operation. The SN74HCT240N maintains full functionality across this range without derating.
What is the maximum capacitive load the SN74HCT240N can drive while maintaining timing specs?
The SN74HCT240N's switching characteristics are guaranteed for CL = 50pF and CL = 150pF loads. At 50pF, tpd is 32ns max (5.5V); at 150pF, tpd rises to 48ns max. Beyond 150pF, timing degrades nonlinearly and is not characterized. For reliable 25MHz operation, total net capacitance-including trace, stubs, and receiver inputs-must remain ≤150pF. The SN74HCT240N's 6mA drive strength supports this within typical PCB layouts.
Is the SN74HCT240N RoHS compliant and lead-free?
Yes, the SN74HCT240N is RoHS compliant and features lead-free (NiPdAu) termination. Per TI's packaging documentation, it carries "Yes" in the RoHS column and "NIPDAU" as the lead finish. The device meets JEDEC J-STD-020 moisture sensitivity Level-1 (unlimited floor life at ≤30°C/85% RH) and is rated for reflow up to 260°C peak. The SN74HCT240N is qualified for industrial temperature range (–40°C to +85°C) and shipped in tube packaging (20 units per tube).
SN74HCT240N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HCT
- 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:
- 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
SN74HCT240N FAQ
1.How can I place an order for SN74HCT240N through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HCT240N 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 SN74HCT240N reliable?
The price and inventory of SN74HCT240N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HCT240N is usually 5 days.
3.What payment methods are accepted for SN74HCT240N?
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4.How is shipping managed for SN74HCT240N?
SN74HCT240N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HCT240N 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 SN74HCT240N?
For technical support, including SN74HCT240N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HCT240N requirements.
6.How does Aetrix verify that SN74HCT240N is sourced from the original manufacturer or authorized distributors?
All SN74HCT240N 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 SN74HCT240N meets industry standards.
7.What is the process for return or replacement of SN74HCT240N?
All SN74HCT240N units undergo pre-shipment inspection (PSI). If there is an issue with SN74HCT240N, 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 SN74HCT240N part is unused and in its original packaging.
Return procedure for SN74HCT240N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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