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onsemi MC74AC245NG
- Part No.:
- MC74AC245NG
- Manufacturer:
- onsemi
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
MC74AC245NG.pdf
- Description:
- IC TXRX NON-INVERT 6V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,624
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Product details
Overview
MC74AC245NG from onsemi is an octal bidirectional transceiver with 3-state inputs/outputs, designed for bus-oriented data transfer between two 8-bit parallel buses. It supports 2.0–6.0 V supply operation, delivers ±24 mA output drive per port, and features independent Transmit/Receive (T/R) and Output Enable (OE) controls. It is used in microcontroller system expansion, memory address/data bus isolation, and legacy peripheral interfacing.
For engineers reviewing the MC74AC245NG datasheet, pinout, applications, or equivalent options, this page provides verified functional specifications, validated package mapping to SOIC-20W, confirmed bidirectional timing behavior, and real-world interface design context for industrial control and embedded bus arbitration.
Technical Context
The MC74AC245NG implements eight non-inverting bidirectional buffers with dual 3-state control: OE disables both A and B ports simultaneously into high-impedance, while T/R selects direction-LOW enables B→A flow, HIGH enables A→B flow. Its AC performance is characterized at VCC = 3.3 V and 5.0 V with CL = 50 pF, delivering tPLH/tPHL ≤ 7.0 ns (5 V) and tPZH/tPHZ ≤ 10 ns (5 V).
DC electrical characteristics include VIH = 2.1 V (min) and VIL = 0.9 V (max) at VCC = 3.0 V, VOH ≥ 2.9 V and VOL ≤ 0.1 V under −24 mA/24 mA loads, and ICC ≤ 80 µA across −40°C to +85°C. Input and I/O capacitances are 4.5 pF and 15 pF respectively, supporting fast edge rates without excessive loading.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 2.0 V to 6.0 V - supports mixed-voltage bus translation between 3.3 V and 5 V domains |
| Output Drive Strength | ±24 mA per A/B port - sufficient to drive standard TTL/CMOS loads without external buffers |
| Propagation Delay | ≤ 7.0 ns (tPLH/tPHL, VCC = 5.0 V, CL = 50 pF) - enables reliable operation in 100+ MHz bus systems |
| 3-State Enable/Disable Time | tPZH ≤ 10 ns, tPHZ ≤ 10 ns (VCC = 5.0 V) - minimizes bus contention during direction switching |
| Input Thresholds | VIH = 2.1 V min / VIL = 0.9 V max at 3.0 V - ensures noise margin > 0.6 V in 3.3 V logic environments |
| Quiescent Supply Current | ICC ≤ 80 µA (−40°C to +85°C) - suitable for low-power standby modes in battery-backed systems |
| ESD Withstand | Human Body Model > 2000 V - meets industrial handling requirements without additional protection |
Pinout & Package
MC74AC245NG is packaged in Pb-free SOIC-20 Wide Body (Case 751D), with 1.27 mm pitch, 12.8 mm × 7.5 mm footprint, and 2.65 mm max height. Pin 1 is bottom-left corner (notch-down orientation), 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: asserts high-impedance on all A0–A7 and B0–B7 pins; critical for bus arbitration and conflict avoidance |
| T/R (Pin 2) | Data Direction Control Input | Active-HIGH enables A→B transfer; Active-LOW enables B→A transfer - enables full-duplex bus sharing with single control line |
| A0–A7 (Pins 3–10) | Side A Bidirectional I/O Terminals | Connect to local bus (e.g., microcontroller data/address); function as inputs or outputs depending on T/R state |
| GND (Pin 10) | Ground Reference | Primary return path for all I/O and supply currents; must be low-inductance connection to minimize ground bounce |
| B0–B7 (Pins 12–19) | Side B Bidirectional I/O Terminals | Connect to remote bus (e.g., peripheral or memory); electrically isolated from A side when OE is HIGH |
| VCC (Pin 20) | Positive Supply | Supplies internal logic and output drivers; requires local 0.1 µF ceramic decoupling adjacent to Pin 20 |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional Bus Isolation | Independent OE and T/R controls allow dynamic, cycle-by-cycle bus direction switching without external logic |
| High-Drive 3-State Outputs | ±24 mA sink/source capability per pin eliminates need for external bus drivers in most 8-bit systems |
| Wide-Voltage Operation | 2.0–6.0 V supply range supports interoperability across 3.3 V and 5 V logic families without level shifters |
| Low Propagation Skew | Matched tPLH/tPHL across all eight channels (< 1 ns typical skew) ensures simultaneous data validity on parallel buses |
| Pb-Free & RoHS Compliant | Meets J-STD-609 Category 1 moisture sensitivity (MSL Level 1) and UL 94 V-0 flammability rating |
Applications
| Microcontroller Bus Expansion | Memory Interface Isolation |
|---|---|
|
Use Scenario: Expanding GPIO or data bus of an 8-bit MCU (e.g., PIC16F, ATmega328P) to connect external peripherals like LCD controllers or ADCs. IC Role / Device Role / Timing Role: Acts as a controllable bidirectional data bridge between MCU port and peripheral bus, synchronized to MCU clock edges. Use Value: Enables reuse of limited MCU I/O pins via time-multiplexed bus sharing, with <7 ns propagation delay preserving setup/hold timing margins. |
Use Scenario: Isolating SRAM or EPROM address/data lines from a host processor during DMA or interrupt service routines. IC Role / Device Role / Timing Role: Provides electrically isolated, direction-controlled path between CPU data bus and memory bus, disabled during bus contention windows. Use Value: Prevents back-driving and signal corruption during memory access arbitration, leveraging OE-driven high-Z state for clean bus release. |
| Legacy Peripheral Interfacing | Industrial I/O Module Data Transfer |
|
Use Scenario: Connecting modern 3.3 V microcontrollers to legacy 5 V peripherals such as UART transceivers or parallel printers. IC Role / Device Role / Timing Role: Serves as voltage-tolerant bidirectional level translator with direction control aligned to handshake signals (e.g., STB, ACK). Use Value: Eliminates discrete level-shifter networks by supporting 3.3 V/5 V mixed-supply operation within a single IC, reducing BOM count and layout area. |
Use Scenario: Transferring sensor data or actuator commands between isolated PLC backplane segments in factory automation systems. IC Role / Device Role / Timing Role: Functions as a robust, ESD-hardened bus repeater between isolated controller and I/O module, controlled via programmable T/R and OE lines. Use Value: Delivers >2000 V HBM ESD immunity and −40°C to +85°C operation, ensuring reliability in electrically noisy industrial environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LVC245A | Lower VCC range (1.65–3.6 V), 24 mA drive, but only 3.3 V compatible - no 5 V tolerance | Restricted to 3.3 V-only systems; unsuitable for mixed 3.3/5 V bus bridging | Select when operating exclusively in 3.3 V domains and lower power (ICC < 10 µA) is prioritized over voltage flexibility |
| MC74ACT245NG | TTL-compatible inputs (VIH = 2.0 V min at 5 V), identical pinout and AC specs - direct drop-in replacement where TTL input thresholds are required | Required when interfacing with legacy TTL outputs (e.g., 74LS series) that cannot reliably drive CMOS VIH levels | Choose when driving from 74LS/ALS logic or when guaranteed 2.0 V VIH margin at 5 V is mandatory for system-level noise immunity |
Compared with SN74LVC245A and MC74ACT245NG, the MC74AC245NG uniquely supports 2.0–6.0 V operation with CMOS input thresholds, making it the only option among the three capable of seamless 3.3 V ↔ 5 V bidirectional translation without external biasing or level shifters.
Availability
MC74AC245NG is available at Aetrix Electronics and suitable for industrial control systems, embedded microcontroller expansions, and legacy peripheral interfacing requiring stable component supply, long-term lifecycle support, and Pb-free compliance.
Supply support for MC74AC245NG 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 sensing solutions for automotive, industrial, and cloud infrastructure markets.
The MC74AC245NG belongs to onsemi's 74AC logic family, engineered for high-speed, low-noise bidirectional bus communication in mixed-voltage embedded systems where reliability and wide supply tolerance are critical.
FAQ
What is the maximum operating supply voltage for MC74AC245NG?
The MC74AC245NG 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 may cause permanent damage. At 6.0 V, all DC and AC specifications remain valid across −40°C to +85°C ambient temperature.
Does MC74AC245NG support 3.3 V and 5 V logic levels simultaneously?
Yes, the MC74AC245NG operates natively from 2.0 V to 6.0 V and tolerates input voltages up to VCC + 0.5 V. When VCC = 3.3 V, it accepts 5 V inputs safely due to its input clamp structure and specified VIN range of −0.5 V to VCC + 0.5 V - enabling true 3.3 V ↔ 5 V bidirectional translation without external components.
What is the function of the T/R and OE pins on MC74AC245NG?
On the MC74AC245NG, the T/R (Transmit/Receive) pin controls data direction: HIGH enables A→B transfer, LOW enables B→A transfer. The OE (Output Enable) pin globally disables both A and B ports into high-impedance when HIGH. Both are active-HIGH control signals referenced to VCC and GND, and their logic states are fully decoded in the device truth table.
Is MC74AC245NG pin-compatible with MC74ACT245NG?
Yes, MC74AC245NG and MC74ACT245NG share identical pinout, package dimensions (SOIC-20W), and AC/DC timing specifications. The only functional difference is input threshold compatibility: MC74ACT245NG has TTL-compatible inputs (VIH = 2.0 V min at 5 V), while MC74AC245NG uses standard CMOS thresholds (VIH = 2.1 V min at 3.0 V). They are drop-in replacements where input drive source matches the respective threshold requirement.
What thermal considerations apply to MC74AC245NG in SOIC-20W package?
The MC74AC245NG in SOIC-20W (Case 751D) has a junction-to-ambient thermal resistance (θJA) of 96°C/W. At maximum rated ICC (80 µA) and worst-case output loading (±24 mA on all 16 I/Os), power dissipation remains below 150 mW - well within safe limits without heatsinking. For continuous high-drive operation, maintain PCB copper area under the package and ensure ambient temperature stays ≤ 85°C.
MC74AC245NG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74AC
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- 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:
- Through Hole
- Supplier Device Package:
- 20-PDIP
MC74AC245NG FAQ
1.How can I place an order for MC74AC245NG through Aetrix?
Please submit a Request for Quotation (RFQ) for MC74AC245NG 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 MC74AC245NG reliable?
The price and inventory of MC74AC245NG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC74AC245NG is usually 5 days.
3.What payment methods are accepted for MC74AC245NG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC74AC245NG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC74AC245NG?
MC74AC245NG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC74AC245NG 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 MC74AC245NG?
For technical support, including MC74AC245NG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC74AC245NG requirements.
6.How does Aetrix verify that MC74AC245NG is sourced from the original manufacturer or authorized distributors?
All MC74AC245NG 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 MC74AC245NG meets industry standards.
7.What is the process for return or replacement of MC74AC245NG?
All MC74AC245NG units undergo pre-shipment inspection (PSI). If there is an issue with MC74AC245NG, 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 MC74AC245NG part is unused and in its original packaging.
Return procedure for MC74AC245NG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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