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onsemi MC74ACT240N
- Part No.:
- MC74ACT240N
- Manufacturer:
- onsemi
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
MC74ACT240N.pdf
- Description:
- IC BUFF INVERT 5.5V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,875
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Product details
Overview
MC74ACT240N from onsemi is an octal 3-state buffer/line driver with TTL-compatible inputs, designed for memory address driving, clock distribution, and bidirectional bus interfacing in industrial and embedded systems. It delivers ±24 mA output drive, operates at 4.5 V to 5.5 V supply, and features propagation delays as low as 6.0 ns (typ) at 5 V.
For engineers reviewing the MC74ACT240N datasheet, pinout, applications, or equivalent options, key selection criteria include its 3-state bus-driving capability, TTL input compatibility, guaranteed 24 mA sink/source per output, and SOIC-20 package suitability for high-density PCB layouts.
Technical Context
The MC74ACT240N implements dual independent 4-bit non-inverting buffers, each controlled by a dedicated 3-state enable (OE1/OE2). Its TTL-compatible inputs accept 2.0 V VIH and 0.8 V VIL thresholds at 5 V operation, enabling direct interfacing with legacy 5 V logic families without level translation.
Each output supports high-impedance tri-state control with tPZH/tPLZ enable/disable times ≤9.5 ns (max) and tPHZ/tPLZ disable times ≤10.5 ns (max) at 5 V/50 pF, ensuring clean bus arbitration in shared-data-path applications such as address latching and peripheral multiplexing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - Ensures stable operation across standard 5 V rail tolerances without undervoltage lockout or overvoltage stress. |
| Output Drive | ±24 mA - Supports direct connection to 50 Ω transmission lines or multiple LS-TTL loads without external buffering. |
| Propagation Delay | 6.0 ns (typ) at 5 V - Enables reliable timing in sub-100 MHz address/data bus cycles with margin for setup/hold. |
| Input Thresholds | VIH = 2.0 V, VIL = 0.8 V - Guarantees noise-immune recognition of TTL-level signals from microcontrollers or legacy peripherals. |
| 3-State Leakage | ±0.5 μA (max) - Minimizes bus contention current when outputs are disabled, critical for low-power standby modes. |
| Operating Temperature | −40 °C to +85 °C - Qualified for industrial ambient environments including factory automation and motor control cabinets. |
Pinout & Package
MC74ACT240N is housed in a 20-pin SOIC wide-body (Case 751D) package measuring 12.8 mm × 7.5 mm × 2.65 mm, with 1.27 mm pitch and Pb-free finish. Pin 10 is GND and Pin 20 is VCC; dual OE controls (Pins 1 and 19) independently gate two 4-bit sections.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | Output Enable (OE1, OE2) | Active-low enables for Sections A (Pins 2–9) and B (Pins 11–18); independent control allows staggered bus access. |
| 2–5, 11–14 | Data Inputs (D1–D4, D5–D8) | Non-inverting inputs accepting TTL-compatible logic levels; no internal pull-ups or hysteresis. |
| 6–9, 15–18 | 3-State Outputs (Y1–Y4, Y5–Y8) | Buffered outputs with ±24 mA drive; high-impedance state asserted when respective OE is HIGH. |
| 10 | GND | Signal and power ground reference for all I/O and internal logic; must be low-inductance connection. |
| 20 | VCC | Primary 5 V supply; decoupling capacitor (0.1 μF ceramic) required within 5 mm of this pin. |
Key Features
| Feature | Design Value |
|---|---|
| TTL-compatible inputs | VIH = 2.0 V / VIL = 0.8 V at 5 V - Eliminates need for external level shifters when interfacing with 5 V microcontrollers or FPGAs. |
| 24 mA output sink/source | Drives up to 10 LS-TTL loads or one 50 Ω line - Reduces component count in bus-driver stages and eliminates discrete transistor buffers. |
| Dual independent 3-state controls | OE1 (Pin 1) and OE2 (Pin 19) - Enables time-multiplexed access to two memory banks or peripheral groups on a shared data bus. |
| Pb-free SOIC-20 package | RoHS-compliant, JEDEC-standard footprint - Ensures drop-in compatibility with existing 20-pin SOIC reflow profiles and pick-and-place tooling. |
Applications
| Memory Address Buffering | Microcontroller Bus Interface |
|---|---|
Use Scenario: Driving 16-bit address lines from a microcontroller to external SRAM or EPROM in an industrial PLC. IC Role / Device Role / Timing Role: Non-inverting octal buffer providing fan-out and noise immunity while maintaining tight propagation delay matching across all bits. Use Value: Prevents address skew-induced memory access errors and supports sustained 20 MHz bus clocking with deterministic timing margins. |
Use Scenario: Isolating and driving a shared 8-bit data bus between an ARM Cortex-M4 and multiple peripherals (ADC, DAC, EEPROM). IC Role / Device Role / Timing Role: Bidirectional 3-state bus transceiver section (using OE-controlled directionality) enabling conflict-free multi-peripheral communication. Use Value: Enables single-bus resource sharing without external direction-control logic, reducing PCB routing complexity and BOM count. |
| Legacy System Clock Distribution | Industrial I/O Expansion |
Use Scenario: Distributing a 5 MHz system clock from a crystal oscillator to multiple synchronous logic blocks in a test equipment chassis. IC Role / Device Role / Timing Role: Low-skew clock driver with matched trace-length compensation via identical propagation paths per output. Use Value: Maintains <100 ps inter-output skew, preventing metastability in clocked FIFOs and state machines across distributed modules. |
Use Scenario: Expanding GPIO count on a programmable logic controller by connecting 8 digital input sensors to a host MCU's limited parallel port. IC Role / Device Role / Timing Role: Input buffer stage converting noisy field-side 5 V sensor signals into clean, rail-to-rail logic levels for MCU sampling. Use Value: Provides 24 mA drive strength and ±2 kV ESD protection (HBM), eliminating need for external transient suppressors on industrial I/O lines. |
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 |
|---|---|---|---|
| SN74ACT240N | Identical electrical specs and pinout; TI-manufactured with same AC/DC characteristics and 5 V operation range. | No functional deviation - validated for identical bus-driving and memory-address roles. | Select when requiring dual-source procurement or TI-specific qualification documentation. |
| MC74ACT244N | Octal non-inverting buffer with identical pinout but single OE control (Pin 1 only); no OE2 terminal. | Lacks independent section gating - unsuitable for split-bus architectures requiring staggered enable timing. | Choose only for simpler unidirectional bus applications where dual-OE control is unnecessary. |
Compared with SN74ACT240N, MC74ACT240N offers identical performance and second-source availability; versus MC74ACT244N, it provides critical dual-OE flexibility for time-sliced bus arbitration but requires additional PCB routing for OE2.
Availability
MC74ACT240N is available at Aetrix Electronics and suitable for industrial control systems, legacy instrumentation upgrades, and embedded memory interface designs requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for MC74ACT240N 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
onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, logic, and sensing solutions for automotive, industrial, and cloud infrastructure markets.
The MC74ACT240N belongs to onsemi's advanced CMOS logic family, engineered specifically for robust 5 V bus interfacing in industrial and legacy-system upgrade applications where TTL compatibility and high noise immunity are mandatory.
FAQ
What is the maximum operating supply voltage for MC74ACT240N?
The MC74ACT240N has an absolute maximum VCC rating of +6.5 V, but its recommended operating range is strictly 4.5 V to 5.5 V. Operation outside this window risks violating input threshold specifications and may cause excessive ICC or reduced noise margin. The MC74ACT240N must be powered within 4.5–5.5 V to guarantee full compliance with VOH/VOL, propagation delay, and 3-state leakage specs.
Does MC74ACT240N support mixed-voltage interfacing, such as 3.3 V inputs?
No - the MC74ACT240N is not designed for 3.3 V input compatibility. Its VIH minimum is 2.0 V at 5 V VCC, and it lacks input clamp diodes or level-shifting circuitry. Applying 3.3 V logic signals may result in marginal or undefined switching behavior. For mixed-voltage systems, use a dedicated level translator or select a 3.3 V–tolerant buffer like the MC74LCX240 instead of the MC74ACT240N.
How does the dual OE architecture of MC74ACT240N improve bus arbitration?
The MC74ACT240N uses separate OE1 (Pin 1) and OE2 (Pin 19) to independently control two 4-bit sections (Y1–Y4 and Y5–Y8). This allows time-staggered enable/disable sequencing - for example, asserting OE1 first to drive lower address bits while holding OE2 inactive - preventing bus contention during partial writes. This capability is absent in single-OE alternatives like the MC74ACT244N and is intrinsic to the MC74ACT240N's design.
What is the thermal resistance (θJA) of MC74ACT240N in its SOIC-20 package?
The MC74ACT240N in SOIC-20 (Case 751D) has a junction-to-ambient thermal resistance (θJA) of 96 °C/W, as specified in the Maximum Ratings table. This value assumes standard JEDEC 2-layer board conditions (1-inch² copper pad). Under worst-case 5.5 V/24 mA per output operation, junction temperature rise remains within safe limits (<140 °C) up to +85 °C ambient, confirming suitability for enclosed industrial enclosures without forced airflow.
Is MC74ACT240N pin-compatible with older 74AC240 devices?
Yes - the MC74ACT240N shares identical pinout, package dimensions, and DC/AC timing behavior with the MC74AC240, except for input threshold levels. While the MC74AC240 requires ≥3.15 V VIH at 4.5 V VCC, the MC74ACT240N accepts ≥2.0 V, making it backward-compatible in all circuits where the AC version was used, but with improved noise immunity and TTL interoperability. Both devices use the same SOIC-20 footprint and can be substituted without PCB changes.
MC74ACT240N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74ACT
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Logic Type:
- Buffer, Inverting
- Number of Elements:
- 2
- Number of Bits per Element:
- 4
- Input Type:
- -
- Output Type:
- 3-State
- Current - Output High, Low:
- 24mA, 24mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
MC74ACT240N FAQ
1.How can I place an order for MC74ACT240N through Aetrix?
Please submit a Request for Quotation (RFQ) for MC74ACT240N 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 MC74ACT240N reliable?
The price and inventory of MC74ACT240N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC74ACT240N is usually 5 days.
3.What payment methods are accepted for MC74ACT240N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC74ACT240N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC74ACT240N?
MC74ACT240N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC74ACT240N 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 MC74ACT240N?
For technical support, including MC74ACT240N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC74ACT240N requirements.
6.How does Aetrix verify that MC74ACT240N is sourced from the original manufacturer or authorized distributors?
All MC74ACT240N 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 MC74ACT240N meets industry standards.
7.What is the process for return or replacement of MC74ACT240N?
All MC74ACT240N units undergo pre-shipment inspection (PSI). If there is an issue with MC74ACT240N, 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 MC74ACT240N part is unused and in its original packaging.
Return procedure for MC74ACT240N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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