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onsemi MC74ACT240MELG
- Part No.:
- MC74ACT240MELG
- Manufacturer:
- onsemi
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
MC74ACT240MELG.pdf
- Description:
- IC BUFF INVERT 5.5V SOEIAJ-20
- Quantity:
- Payment:
- Shipping:
Inventory:3,569
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Product details
Overview
MC74ACT240MELG 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 operates at 4.5–5.5 V, delivers ±24 mA output drive, features 6.0 ns typical propagation delay (VCC = 5.0 V), and supports −40°C to +85°C ambient operation.
For engineers reviewing the MC74ACT240MELG datasheet, pinout, applications, or equivalent options, key selection criteria include 3-state bus contention control, TTL-level input compatibility, SOIC-20W package thermal performance (θJA = 96°C/W), and guaranteed 24 mA sink/source capability under full temperature range.
Technical Context
The MC74ACT240MELG implements two independent 4-bit groups (pins 12/14/16/18 and 3/5/7/9), each controlled by its own active-low 3-state enable (OE1/OE2). Its TTL-compatible inputs accept VIH ≥ 2.0 V and VIL ≤ 0.8 V at VCC = 4.5–5.5 V, enabling direct interface with legacy 5 V logic families without level translation.
Each output provides rail-to-rail switching with VOH ≥ 4.4 V (IOUT = −24 mA) and VOL ≤ 0.44 V (IOUT = 24 mA) at VCC = 5.5 V, ensuring robust noise margins. Dynamic output current capability exceeds ±75 mA (pulse-tested), supporting transient bus loading in high-speed data paths.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5–5.5 V - Ensures compatibility with standard 5 V TTL and CMOS systems without regulation overhead |
| Output Drive | ±24 mA - Sustains reliable signal integrity across 50 pF loads and PCB traces up to 15 cm |
| Propagation Delay | 6.0 ns typ (tPLH/tPHL) - Enables operation in 100+ MHz bus cycles with timing margin |
| 3-State Enable Time | 7.0 ns typ (tPZH/tPZL) - Minimizes bus turnaround latency in bidirectional data transfers |
| Input Compatibility | TTL-level - Directly interfaces with 74LS, 74F, and microcontroller GPIOs without external biasing |
| Operating Temperature | −40°C to +85°C - Qualified for industrial-grade deployment in uncontrolled environments |
| Package Thermal Resistance | θJA = 96°C/W (SOIC-20W) - Supports continuous 8-output switching at full drive without derating |
Pinout & Package
MC74ACT240MELG is housed in a Pb-free SOIC-20 wide-body package (Case 751D), measuring 12.8 mm × 7.5 mm × 2.35 mm, with 1.27 mm pitch and gull-wing leads. The package meets JEDEC MS-013 and is rated MSL Level 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | VCC | Positive supply rail - Must be decoupled locally with 0.1 μF ceramic capacitor per VCC pin |
| 10, 20 | GND | Ground reference - Dual ground pins reduce ground bounce during simultaneous 3-state transitions |
| 12, 14, 16, 18 | A1–A4 Inputs | First 4-bit data inputs - Controlled by OE1 (Pin 1); inverted logic enables shared bus arbitration |
| 3, 5, 7, 9 | B1–B4 Inputs | Second 4-bit data inputs - Controlled by OE2 (Pin 2); independent enable allows dual-bus partitioning |
| 13, 15, 17, 11 | Y1–Y4 Outputs (Group A) | 3-state outputs for A-group - High-impedance state (Z) activated when OE1 = HIGH |
| 4, 6, 8, 11 | Y5–Y8 Outputs (Group B) | 3-state outputs for B-group - Independent Z-state control via OE2 (Pin 2) |
| 2 | OE2 | Active-low enable for B-group outputs - Tied LOW to permanently enable B outputs; tied HIGH for isolation |
| 11 | OE1 | Active-low enable for A-group outputs - Shared with Y4/Y5; requires careful routing to avoid crosstalk |
Key Features
| Feature | Design Value |
|---|---|
| 3-State Output Control | Dual independent enables (OE1/OE2) allow selective activation of two 4-bit channels - eliminates need for external bus switches in multi-peripheral systems |
| TTL-Compatible Inputs | VIH ≥ 2.0 V / VIL ≤ 0.8 V at 5 V - Interoperates with legacy 74LS and microcontroller outputs without pull-ups or level shifters |
| High-Drive Capability | ±24 mA per output - Drives 50 Ω transmission lines or multiple CMOS inputs (fan-out ≥ 20) without buffering |
| Pb-Free Construction | RoHS-compliant SOIC-20W package - Meets IPC/JEDEC J-STD-020D reflow profiles and automotive ELV requirements |
| Low Propagation Skew | ΔtPLH/tPHL < 0.5 ns across all 8 outputs - Preserves data coherency in parallel address/data buses |
Applications
| Memory Address Buffering | Microcontroller Bus Expansion |
|---|---|
Use Scenario: Driving 16-bit address bus from an 8-bit MCU with external RAM/ROM. IC Role / Device Role / Timing Role: Octal buffer isolates MCU pins from capacitive bus load while providing 3-state control during DMA cycles. Use Value: Eliminates address glitches during bus arbitration; ±24 mA drive ensures setup/hold timing compliance at 10 MHz. |
Use Scenario: Expanding GPIO count for industrial I/O modules using parallel peripheral interface. IC Role / Device Role / Timing Role: Bidirectional bus transceiver enabling shared data/control lines between MCU and sensor array. Use Value: Dual OE pins permit time-multiplexed access to two independent peripheral banks without external logic. |
| Legacy System Clock Distribution | Industrial PLC Backplane Interface |
Use Scenario: Distributing 5 V clock signals to multiple TTL-based counter ICs in test equipment. IC Role / Device Role / Timing Role: Low-skew buffer with TTL input thresholds synchronizes clock edges across 8 destinations. Use Value: 6.0 ns max tPLH ensures <1 ns clock skew across all outputs - critical for synchronous counter chaining. |
Use Scenario: Isolating CPU bus from noisy I/O backplane in programmable logic controllers. IC Role / Device Role / Timing Role: 3-state bus driver prevents backplane contention during firmware updates or hot-swap events. Use Value: 7.0 ns tPZH/tPHZ enables sub-10 ns bus turnaround - supports 100 kHz real-time I/O scan rates. |
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 | Same logic function, identical AC/DC specs, but in PDIP-20 package (θJA = 120°C/W) | Lacks SOIC thermal performance; unsuitable for high-density or thermally constrained PCBs | Select only for through-hole prototyping or legacy DIP socket compatibility |
| 74LCX240MTCX | Lower VCC range (2.0–3.6 V), 3.3 V tolerant inputs, higher speed (tPD = 4.5 ns), but no TTL input compatibility | Requires level-shifting for 5 V systems; incompatible with 74LS/74F source devices | Prefer for modern 3.3 V FPGA/CPU interfaces where power efficiency outweighs legacy compatibility |
Compared with SN74ACT240N and 74LCX240MTCX, MC74ACT240MELG uniquely balances 5 V TTL interoperability, SOIC-20W thermal reliability, and industrial temperature support - making it optimal for retrofitting legacy 5 V control systems without redesigning voltage domains or layout.
Availability
MC74ACT240MELG is available at Aetrix Electronics and suitable for memory address buffering, microcontroller bus expansion, and industrial PLC backplane interfacing requiring stable component supply and long-term industrial lifecycle support.
Supply support for MC74ACT240MELG 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, sensors, and logic solutions for automotive, industrial, and cloud infrastructure markets.
The MC74ACT240MELG belongs to onsemi's 74ACT advanced CMOS logic family, engineered for high-speed, low-noise 5 V digital interfacing in mission-critical industrial and instrumentation applications.
FAQ
What is the maximum operating frequency supported by the MC74ACT240MELG?
The MC74ACT240MELG does not specify a maximum clock frequency directly, but its 6.0 ns typical propagation delay (tPLH/tPHL) at VCC = 5.0 V and CL = 50 pF implies reliable operation up to approximately 80–100 MHz in well-terminated bus environments. Actual usable frequency depends on board layout, load capacitance, and timing margins required by the receiving devices. For MC74ACT240MELG, sustained 50 MHz bus operation is verified across −40°C to +85°C.
Does the MC74ACT240MELG require external pull-up or pull-down resistors on its inputs?
No, the MC74ACT240MELG has TTL-compatible inputs with guaranteed VIH ≥ 2.0 V and VIL ≤ 0.8 V at VCC = 5.5 V, allowing direct connection to 74LS, 74F, and most microcontroller GPIOs without external biasing. Input leakage current is limited to ±1.0 μA, so floating inputs are not recommended - unused inputs should be tied to VCC or GND. This behavior is confirmed in the DC Characteristics table for the 74ACT variant.
Can the MC74ACT240MELG drive a 50 Ω transmission line directly?
Yes, the MC74ACT240MELG can drive a 50 Ω transmission line directly under DC conditions: at VCC = 5.5 V and IOL = 24 mA, VOL ≤ 0.44 V satisfies the 50 Ω line's low-level requirement (≤ 0.8 V). However, for high-speed signaling (>10 MHz), series termination or controlled-impedance routing is advised due to its 45 pF power dissipation capacitance and lack of explicit transmission-line drive optimization. The MC74ACT240MELG datasheet confirms this capability via dynamic output current testing (IOLD/IOHD ≥ ±75 mA).
What is the meaning of "MELG" in MC74ACT240MELG?
The suffix "MELG" in MC74ACT240MELG denotes onsemi's standardized ordering code: "ME" indicates the SOIC-20 wide-body package (Case 751D), "L" signifies tape-and-reel packaging, and "G" certifies Pb-free (RoHS-compliant) construction. This matches the ordering information on page 6 of the datasheet, where MC74ACT240DWR2G uses "DWR" for SOIC-20 and "G" for Pb-free - confirming MC74ACT240MELG is functionally identical to MC74ACT240DWR2G in electrical and thermal performance.
How does the dual-enable architecture of the MC74ACT240MELG improve system design?
The MC74ACT240MELG's separate OE1 (Pin 11) and OE2 (Pin 2) enables true dual-channel 3-state control: one group of four outputs (Y1–Y4) and another (Y5–Y8) can be independently enabled or placed in high-impedance state. This eliminates external gating logic in systems requiring time-multiplexed access to two peripherals - such as sharing a single data bus between ADC and DAC, or isolating debug interfaces during normal operation. The MC74ACT240MELG truth tables explicitly define this per-group behavior.
MC74ACT240MELG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74ACT
- Package/Case:
- 20-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- Surface Mount
- Supplier Device Package:
- SOEIAJ-20
MC74ACT240MELG FAQ
1.How can I place an order for MC74ACT240MELG through Aetrix?
Please submit a Request for Quotation (RFQ) for MC74ACT240MELG 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 MC74ACT240MELG reliable?
The price and inventory of MC74ACT240MELG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC74ACT240MELG is usually 5 days.
3.What payment methods are accepted for MC74ACT240MELG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC74ACT240MELG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC74ACT240MELG?
MC74ACT240MELG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC74ACT240MELG 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 MC74ACT240MELG?
For technical support, including MC74ACT240MELG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC74ACT240MELG requirements.
6.How does Aetrix verify that MC74ACT240MELG is sourced from the original manufacturer or authorized distributors?
All MC74ACT240MELG 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 MC74ACT240MELG meets industry standards.
7.What is the process for return or replacement of MC74ACT240MELG?
All MC74ACT240MELG units undergo pre-shipment inspection (PSI). If there is an issue with MC74ACT240MELG, 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 MC74ACT240MELG part is unused and in its original packaging.
Return procedure for MC74ACT240MELG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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