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onsemi MC74AC245MG
- Part No.:
- MC74AC245MG
- Manufacturer:
- onsemi
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
MC74AC245MG.pdf
- Description:
- IC TXRX NON-INVERT 6V SOEIAJ-20
- Quantity:
- Payment:
- Shipping:
Inventory:1,482
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Product details
Overview
MC74AC245MG from onsemi is an octal bidirectional transceiver with 3-state inputs/outputs, designed for bus interface applications between two data buses. It supports 2.0–6.0 V supply operation, delivers ±24 mA output drive at both A and B ports, and uses active-HIGH Transmit/Receive (T/R) and active-HIGH Output Enable (OE) control logic. It is used in microprocessor bus buffering, memory address/data bus isolation, and level-translating I/O expansion.
For engineers reviewing the MC74AC245MG datasheet, pinout, applications, or equivalent options, key selection criteria include bidirectional bus direction control timing (tPLH/tPHL ≤ 7.0 ns @ 5 V), 3-state enable/disable latency (tPZH/tPHZ ≤ 10 ns), output drive strength (±24 mA), and SOIC-20W Pb-free packaging compatibility with industrial temperature range (−40°C to +85°C).
Technical Context
The MC74AC245MG implements eight independent non-inverting bidirectional buffers with dual 3-state control: OE disables both A and B ports simultaneously into high-impedance, while T/R selects data flow direction (A→B when HIGH, B→A when LOW). Its AC characteristics are specified at CL = 50 pF and VCC = 5.0 V ±0.5 V, with propagation delays guaranteed ≤ 7.0 ns (tPLH/tPHL) and output enable/disable times ≤ 11.0 ns (tPZH/tPHZ).
It operates across a wide VCC range (2.0–6.0 V) with TTL-compatible input thresholds only in the ACT variant - the MC74AC245MG uses CMOS-compatible VIH/VIL (e.g., VIH = 2.1 V min @ VCC = 3.0 V), enabling interoperability with mixed-voltage systems. Input leakage (IIN ≤ ±1.0 µA) and 3-state off-state current (IOZT ≤ ±6.0 µA) ensure low standby power in bus-hold or hot-swap scenarios.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2.0 V to 6.0 V - supports direct interfacing with 3.3 V and 5 V logic domains without level shifters. |
| Output Drive | ±24 mA per pin - sufficient to drive standard TTL loads and multiple CMOS inputs on shared buses. |
| Propagation Delay | ≤ 7.0 ns @ 5 V, CL = 50 pF - enables reliable operation in high-speed bus cycles up to ~70 MHz. |
| 3-State Enable Time | tPZH ≤ 10 ns @ 5 V - ensures fast bus arbitration and minimizes contention windows during direction switching. |
| Input Thresholds | VIH = 2.1 V min @ 3.0 V; VIL = 0.9 V max @ 3.0 V - CMOS-compatible thresholds prevent false triggering in noisy environments. |
| Operating Temp | −40°C to +85°C - qualified for industrial-grade embedded control, instrumentation, and communications equipment. |
| ESD Rating | > 2000 V HBM - provides robust handling during PCB assembly and field service without external protection. |
Pinout & Package
MC74AC245MG is housed in a 20-pin SOIC Wide Body (SOIC-20W, Case 751D) package with 0.300-inch body width, 1.27 mm pitch, and Pb-free finish (G suffix). Pin 1 is top-left corner, with GND at pin 10 and VCC at pin 20.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| OE (Pin 1) | Global 3-State Enable Input | Active-HIGH signal that places all A0–A7 and B0–B7 pins in high-Z state - essential for bus sharing and conflict avoidance. |
| T/R (Pin 2) | Data Direction Control Input | Active-HIGH selects A→B transfer; active-LOW selects B→A - enables dynamic bidirectional bus arbitration without external logic. |
| A0–A7 (Pins 3–10) | Side A Bidirectional I/O Terminals | Connect to one bus segment (e.g., microcontroller side); function as inputs or outputs depending on T/R state. |
| GND (Pin 10) | Ground Reference | Common return path for all signals and supply current - must be low-inductance connection to minimize ground bounce. |
| B0–B7 (Pins 11–18) | Side B Bidirectional I/O Terminals | Connect to second bus segment (e.g., peripheral/memory side); mirror A-side behavior under T/R control. |
| VCC (Pin 20) | Positive Supply Rail | Primary power source (2.0–6.0 V); decoupling capacitor (0.1 µF ceramic) required within 5 mm of this pin. |
Key Features
| Feature | Design Value |
|---|---|
| Octal bidirectional data path | Eight independent A↔B channels controlled by single T/R line - reduces component count vs. discrete unidirectional buffers. |
| Simultaneous 3-state control | Single OE input disables all 16 I/Os - eliminates bus contention during reset, sleep, or multi-master arbitration. |
| High-output drive (±24 mA) | Drives 10+ LSTTL loads or 20+ CMOS inputs - eliminates need for external bus drivers in mid-density systems. |
| Wide VCC operating range | 2.0–6.0 V operation - supports legacy 5 V, modern 3.3 V, and mixed-supply backplane designs without voltage translation. |
| Pb-free SOIC-20W package | RoHS-compliant, JEDEC-standard footprint - ensures drop-in compatibility with existing SOIC-20 assembly lines and reflow profiles. |
Applications
| Microprocessor Bus Buffering | Memory Address/Data Isolation |
|---|---|
Use Scenario: Interfacing an 8-bit microcontroller data bus to external peripherals with different timing or voltage requirements. IC Role / Device Role / Timing Role: Bidirectional data transceiver managing real-time A↔B data flow under CPU control via T/R and OE. Use Value: Eliminates bus contention during read/write cycles and supports hot-plug peripheral detection via 3-state isolation. | Use Scenario: Isolating RAM/ROM address and data lines from a shared system bus during DMA or debug access. IC Role / Device Role / Timing Role: Direction-controlled buffer enabling CPU-initiated memory transfers while blocking spurious noise coupling. Use Value: Prevents memory corruption during bus arbitration and allows clean bus release before peripheral access. |
| I/O Expansion Interface | Level-Translating Logic Bridge |
Use Scenario: Extending GPIO count of an MCU using parallel I/O expanders or FPGA configuration interfaces. IC Role / Device Role / Timing Role: Bidirectional repeater relaying status/control signals between host and slave devices. Use Value: Maintains signal integrity over longer traces and supports synchronous handshaking protocols like STROBE/ACK. | Use Scenario: Connecting 3.3 V FPGA I/O banks to 5 V legacy peripherals (e.g., displays, sensors, DACs). IC Role / Device Role / Timing Role: Voltage-tolerant transceiver translating logic levels while preserving timing margins. Use Value: Enables interoperability without external level shifters - VIH/VIL thresholds scale with VCC, supporting mixed-supply operation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LVC245A | 3.3 V only (1.65–3.6 V), lower drive (±24 mA), faster tPLH (≤ 5.2 ns @ 3.3 V), smaller TSSOP-20 package. | Optimized for low-voltage portable/embedded systems; not suitable for 5 V buses. | Select when system VCC is strictly 3.3 V and board space is constrained. |
| 74ACT245 | TTL-compatible inputs (VIH = 2.0 V min @ 5 V), identical SOIC-20W package and pinout, same AC/DC specs except input thresholds. | Preferred where legacy TTL logic coexists; requires no input conditioning in mixed-logic designs. | Choose when interfacing with older 5 V TTL components or where guaranteed VIH/VIL margins are critical. |
Compared with SN74LVC245A and 74ACT245, the MC74AC245MG offers broader VCC flexibility (2.0–6.0 V) and CMOS-compatible thresholds ideal for mixed-voltage industrial control, whereas SN74LVC245A targets compact 3.3 V designs and 74ACT245 prioritizes TTL interoperability.
Availability
MC74AC245MG is available at Aetrix Electronics and suitable for industrial control panels, test equipment interfaces, and embedded communication gateways requiring stable component supply and long-term manufacturability.
Supply support for MC74AC245MG 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 focused on energy-efficient innovation for automotive, industrial, cloud, and IoT applications.
The MC74AC245MG belongs to onsemi's 74AC logic family, engineered for high-speed, low-power bus interface solutions in industrial and computing infrastructure where reliability, wide supply tolerance, and robust ESD performance are critical.
FAQ
What is the maximum recommended supply voltage for MC74AC245MG?
The absolute maximum DC supply voltage (VCC) for MC74AC245MG is +6.5 V, but the recommended operating range is 2.0 V to 6.0 V. Operating consistently above 6.0 V risks permanent damage per the datasheet's Maximum Ratings table. For reliable long-term use in industrial applications, design with VCC ≤ 6.0 V and include transient suppression if exposed to inductive load switching. The MC74AC245MG is rated for continuous operation at 6.0 V with full parameter guarantees.
Does MC74AC245MG support hot-swapping or live insertion?
MC74AC245MG is not explicitly qualified for hot-swap operation, but its high-impedance 3-state outputs (IOZT ≤ ±6.0 µA), robust ESD rating (>2000 V HBM), and rail-to-rail input tolerance (VIN = −0.5 V to VCC +0.5 V) provide inherent resilience during live insertion. To safely implement hot-swap, ensure OE is held LOW (disabled) until VCC stabilizes, and use series current-limiting resistors on A/B lines. The MC74AC245MG's design supports such practices but requires external sequencing control.
How does the T/R pin control data direction in MC74AC245MG?
The T/R (Transmit/Receive) pin on MC74AC245MG is an active-HIGH control: when T/R = HIGH, data flows from A ports (A0–A7) to B ports (B0–B7); when T/R = LOW, data flows from B to A. This direction control operates independently of OE - if OE is HIGH, both sides are in high-Z regardless of T/R state. The MC74AC245MG truth table confirms that T/R determines functional direction only when OE is LOW, making it ideal for synchronous bus arbitration protocols.
Can MC74AC245MG be used for level translation between 3.3 V and 5 V logic?
Yes - MC74AC245MG supports level translation because its input thresholds (VIH/VIL) scale with VCC, and it tolerates input voltages from −0.5 V to VCC +0.5 V. When powered at 3.3 V, it reliably accepts 5 V inputs (within absolute max rating), and when powered at 5 V, it outputs 5 V logic compatible with 3.3 V receivers (via series resistor or internal clamping). However, for guaranteed safe 5 V → 3.3 V translation, verify receiver input tolerance; the MC74AC245MG itself does not clamp or regulate output voltage beyond its VCC rail.
What is the thermal resistance (θJA) of MC74AC245MG in its SOIC-20W package?
The junction-to-ambient thermal resistance (θJA) for MC74AC245MG in the SOIC-20W (Case 751D) package is 96°C/W, as specified in the Maximum Ratings table. This value assumes standard JEDEC 2-layer board conditions (1 inch² copper pad, 2 oz Cu). Under full-load conditions (all outputs sourcing/sinking 24 mA), power dissipation may reach ~120 mW, resulting in ~11.5°C junction rise above ambient - well within the 140°C max TJ limit. The MC74AC245MG's low θJA supports reliable operation in enclosed industrial enclosures without forced airflow.
MC74AC245MG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74AC
- Package/Case:
- 20-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Logic Type:
- Transceiver, Non-Inverting
- Number of Elements:
- 1
- Number of Bits per Element:
- 8
- 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
MC74AC245MG FAQ
1.How can I place an order for MC74AC245MG through Aetrix?
Please submit a Request for Quotation (RFQ) for MC74AC245MG 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 MC74AC245MG reliable?
The price and inventory of MC74AC245MG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC74AC245MG is usually 5 days.
3.What payment methods are accepted for MC74AC245MG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC74AC245MG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC74AC245MG?
MC74AC245MG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC74AC245MG 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 MC74AC245MG?
For technical support, including MC74AC245MG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC74AC245MG requirements.
6.How does Aetrix verify that MC74AC245MG is sourced from the original manufacturer or authorized distributors?
All MC74AC245MG 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 MC74AC245MG meets industry standards.
7.What is the process for return or replacement of MC74AC245MG?
All MC74AC245MG units undergo pre-shipment inspection (PSI). If there is an issue with MC74AC245MG, 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 MC74AC245MG part is unused and in its original packaging.
Return procedure for MC74AC245MG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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