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onsemi MC74AC244MELG
- Part No.:
- MC74AC244MELG
- Manufacturer:
- onsemi
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
MC74AC244MELG.pdf
- Description:
- IC BUFF NON-INVERT 6V SOEIAJ-20
- Quantity:
- Payment:
- Shipping:
Inventory:3,110
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Product details
Overview
MC74AC244MELG from onsemi is an octal 3-state buffer/line driver designed for memory address driving, clock distribution, and bidirectional bus interfacing in high-density PCB layouts. It operates from 2.0 V to 6.0 V, delivers ±24 mA output drive, supports −40°C to +85°C ambient operation, and features TTL-compatible inputs only in the ACT variant - this AC version uses CMOS-compatible thresholds. It is used in industrial control backplanes and legacy microprocessor data buses.
For engineers reviewing the MC74AC244MELG datasheet, pinout, applications, or equivalent options, key selection criteria include supply voltage range (2.0–6.0 V), 3-state enable timing (tPZH/tPLZ ≤ 11.5 ns at 5 V), output drive capability (±24 mA), input threshold compatibility (VIH = 2.1 V min @ VCC = 4.5 V), and SOIC-20W package thermal resistance (96 °C/W).
Technical Context
The MC74AC244MELG implements dual 4-bit non-inverting buffers with independent 3-state controls (OE1 for pins 12/14/16/18; OE2 for pins 3/5/7/9). Its CMOS input structure ensures low static current (ICC ≤ 80 µA) and rail-to-rail input voltage tolerance (−0.5 V to VCC + 0.5 V). Output stages are push-pull with symmetrical sourcing/sinking capability.
Propagation delays are specified at CL = 50 pF: tPLH/tPHL ≤ 10.0 ns at VCC = 5.0 V, and 3-state enable/disable times (tPZH/tPLZ/tPHZ/tPLZ) range from 1.5 ns to 11.5 ns across temperature and voltage. Input capacitance is 4.5 pF; power dissipation capacitance is 45 pF.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 2.0 V to 6.0 V - supports mixed-voltage system interfacing and legacy 5 V logic domains |
| Output Drive Current | ±24 mA - sufficient to drive 50 Ω transmission lines or multiple TTL loads without external buffering |
| Propagation Delay | ≤10.0 ns @ 5 V, CL = 50 pF - enables reliable operation in 25 MHz+ address/data bus applications |
| 3-State Enable Time | tPZH ≤ 11.0 ns @ 5 V - ensures fast bus arbitration and minimizes contention windows |
| Input Thresholds | VIH = 2.1 V min @ VCC = 4.5 V; VIL = 1.35 V max - compatible with 3.3 V and 5 V CMOS logic families |
| Operating Temperature | −40°C to +85°C - qualified for industrial-grade embedded control and instrumentation environments |
| Package Thermal Resistance | 96 °C/W (SOIC-20W) - allows sustained 5 V/24 mA operation without forced cooling in typical PCB layouts |
Pinout & Package
MC74AC244MELG is housed in a 20-lead SOIC-20W (Wide Body) package per case 751D, with 1.27 mm pitch, 12.8 mm × 7.5 mm body size, and 2.5 mm height. Pin 1 is top-left corner (notch side), pin 20 is top-right.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | VCC | Positive supply rail - must be decoupled locally; supports 2.0–6.0 V operation |
| 10 | GND | Ground reference - shared return path for all I/O and supply currents |
| 2, 4, 6, 8 | Y1–Y4 (Outputs) | Buffered non-inverting outputs controlled by OE1 - high-impedance when OE1 = HIGH |
| 3, 5, 7, 9 | A1–A4 (Inputs) | Input signals for Y1–Y4 channel group - CMOS-compatible voltage thresholds |
| 12, 14, 16, 18 | Y5–Y8 (Outputs) | Buffered non-inverting outputs controlled by OE2 - high-impedance when OE2 = HIGH |
| 11, 13, 15, 17 | A5–A8 (Inputs) | Input signals for Y5–Y8 channel group - electrically identical to A1–A4 |
| 19 | OE1 | Active-low 3-state enable for Y1–Y4 - LOW enables outputs; HIGH places them in high-Z |
| 20 | OE2 | Active-low 3-state enable for Y5–Y8 - independent control enables split-bus operation |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent 4-bit 3-state control | OE1 and OE2 allow simultaneous or staggered bus release of two 4-bit groups - critical for multiplexed address/data sharing |
| High-output drive (±24 mA) | Eliminates need for external line drivers in 5 V systems driving >10 TTL loads or 50 Ω traces |
| Low quiescent current (ICC ≤ 80 µA) | Reduces standby power in battery-backed or energy-sensitive industrial controllers |
| Wide supply range (2.0–6.0 V) | Enables direct interface between 3.3 V microcontrollers and 5 V peripheral buses without level shifters |
| Pb-free SOIC-20W package | Complies with RoHS Directive 2011/65/EU and supports standard reflow profiles (peak 260 °C) |
Applications
| Industrial Backplane Bus Driver | Microprocessor Address Buffer |
|---|---|
Use Scenario: Driving parallel address lines across a 200 mm PCB backplane with 50 Ω characteristic impedance and 30 pF/node loading. IC Role / Device Role / Timing Role: Non-inverting octal buffer providing signal integrity and fanout expansion while enabling bus isolation via 3-state control. Use Value: ±24 mA drive sustains signal edge rates >10 V/ns over 15 cm traces; tPLH ≤ 10 ns ensures setup/hold compliance at 25 MHz CPU clock. |
Use Scenario: Isolating and strengthening address signals from an 80C86 CPU to multiple memory ICs on a single-layer industrial controller board. IC Role / Device Role / Timing Role: Memory address driver with independent OE1/OE2 allowing interleaved access to ROM and RAM banks. Use Value: Dual enable pins reduce address decode logic; VIH = 2.1 V min ensures reliable recognition of 3.3 V address bits from modern peripherals. |
| Legacy System Clock Distribution | Programmable Logic Interface Buffer |
Use Scenario: Distributing a 12 MHz system clock to four CPLD configuration devices with matched trace lengths and minimal skew. IC Role / Device Role / Timing Role: Low-skew clock driver with symmetrical rise/fall times and low output impedance. Use Value: Propagation delay matching <1 ns between channels maintains <0.5 ns inter-channel skew; VOL ≤ 0.1 V ensures noise margin >0.4 V at 5 V. |
Use Scenario: Interfacing a Xilinx XC9500XL CPLD I/O bank (3.3 V LVTTL) to 5 V discrete logic on a test fixture PCB. IC Role / Device Role / Timing Role: Level-translating buffer with 5 V-tolerant inputs and 5 V output swing. Use Value: Input voltage range (−0.5 V to VCC + 0.5 V) accepts 3.3 V logic safely; VOH ≥ 4.4 V meets 5 V TTL high-level requirement. |
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 |
|---|---|---|---|
| SN74AC244N | Same AC logic family, identical DC/AC specs, but in PDIP-20 package (longer lead inductance, higher thermal resistance) | Preferred for through-hole prototyping or legacy repair; unsuitable for high-frequency or space-constrained designs | Select when manual soldering, breadboarding, or socket-based testing is required |
| MC74ACT244MELG | TTL-compatible inputs (VIH = 2.0 V min @ 5 V), otherwise identical pinout, timing, and drive strength | Better suited for mixed-logic systems with legacy TTL sources; slightly higher ICC at 5 V | Choose when interfacing directly to 74LS or 74F series outputs without level translation |
Compared with SN74AC244N and MC74ACT244MELG, the MC74AC244MELG offers optimal thermal performance (96 °C/W vs. ~120 °C/W for PDIP) and superior high-speed signal integrity in SOIC-20W, while retaining full functional equivalence with the ACT variant except for input threshold levels - making it ideal for new industrial PCB designs requiring density and reliability.
Availability
MC74AC244MELG is available at Aetrix Electronics and suitable for industrial backplane bus drivers, microprocessor address buffering, and legacy clock distribution systems requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for MC74AC244MELG 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 manufacturer specializing in energy-efficient power management, analog, logic, and sensor solutions for automotive, industrial, and cloud infrastructure markets.
The MC74AC244MELG belongs to onsemi's 74AC logic family, engineered for high-speed, low-power, 3-state bus interface applications in industrial control, instrumentation, and legacy computing systems where reliability and wide voltage operation are essential.
FAQ
What is the maximum operating supply voltage for MC74AC244MELG?
The MC74AC244MELG supports a DC supply voltage range of −0.5 V to +6.5 V, with recommended operation from 2.0 V to 6.0 V. Absolute maximum VCC is 6.5 V; exceeding this risks permanent damage. At 6.0 V, output drive remains ±24 mA, and propagation delay improves slightly versus 5.0 V operation - verified per datasheet Section 2 (Maximum Ratings) and Section 3 (Recommended Operating Conditions).
Does MC74AC244MELG support 3.3 V logic inputs?
Yes, MC74AC244MELG accepts 3.3 V logic inputs reliably: its VIH minimum is 2.1 V at VCC = 4.5 V and 2.75 V at VCC = 5.5 V, well above 3.3 V logic HIGH thresholds. Input voltage range extends to −0.5 V to VCC + 0.5 V, ensuring robustness against overshoot. This is confirmed in DC Characteristics Table (Page 3) under VIH/VIL conditions for 74AC devices.
What is the thermal resistance (θJA) of MC74AC244MELG?
The MC74AC244MELG in SOIC-20W (case 751D) has a junction-to-ambient thermal resistance (θJA) of 96 °C/W, as specified in the Maximum Ratings table (Page 2). This value assumes standard JEDEC 2S2P board conditions and enables continuous operation at full output load (±24 mA per pin) up to +85°C ambient without heatsinking - validated in thermal characterization notes (JESD51-7 compliant).
How many independent 3-state control inputs does MC74AC244MELG have?
The MC74AC244MELG has two independent active-low 3-state enable inputs: OE1 (pin 19) controls outputs Y1–Y4 (pins 2,4,6,8), and OE2 (pin 20) controls outputs Y5–Y8 (pins 12,14,16,18). This dual-enable architecture allows selective bus partitioning - e.g., isolating memory address upper/lower bytes - as defined in the Truth Tables (Pages 1–2) and Pinout Diagram.
Is MC74AC244MELG pin-compatible with MC74ACT244MELG?
Yes, MC74AC244MELG is pin-compatible with MC74ACT244MELG: both share identical SOIC-20W pinout, terminal functions, and AC/DC timing specifications except for input threshold levels (ACT has TTL-compatible VIH/VIL). No PCB changes are required when substituting between them - confirmed by onsemi's ordering information table (Page 5) and package mechanical drawings (Case 751D).
MC74AC244MELG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74AC
- Package/Case:
- 20-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Logic Type:
- Buffer, Non-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:
- 2V ~ 6V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOEIAJ-20
MC74AC244MELG FAQ
1.How can I place an order for MC74AC244MELG through Aetrix?
Please submit a Request for Quotation (RFQ) for MC74AC244MELG 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 MC74AC244MELG reliable?
The price and inventory of MC74AC244MELG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC74AC244MELG is usually 5 days.
3.What payment methods are accepted for MC74AC244MELG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC74AC244MELG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC74AC244MELG?
MC74AC244MELG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC74AC244MELG 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 MC74AC244MELG?
For technical support, including MC74AC244MELG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC74AC244MELG requirements.
6.How does Aetrix verify that MC74AC244MELG is sourced from the original manufacturer or authorized distributors?
All MC74AC244MELG 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 MC74AC244MELG meets industry standards.
7.What is the process for return or replacement of MC74AC244MELG?
All MC74AC244MELG units undergo pre-shipment inspection (PSI). If there is an issue with MC74AC244MELG, 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 MC74AC244MELG part is unused and in its original packaging.
Return procedure for MC74AC244MELG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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