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onsemi MC74ACT646DWR2
- Part No.:
- MC74ACT646DWR2
- Manufacturer:
- onsemi
- Package:
- 24-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
MC74ACT646DWR2.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 24SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,704
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Product details
Overview
MC74ACT646DWR2 from onsemi is an octal registered bus transceiver with 3-state outputs and non-inverting data paths, implementing dual-directional real-time and registered data transfer between A and B buses. It features independent A/B registers, TTL-compatible inputs, 24 mA output drive, and operates at 4.5–5.5 V supply. It is used in bidirectional data buffering and register-controlled bus isolation in industrial control backplanes.
For engineers reviewing the MC74ACT646DWR2 datasheet, pinout, applications, or equivalent options, key selection criteria include clock-controlled register loading (CAB/CBA), directional control via DIR/SAB/SBA, 3-state enable via G, and SOIC-24 package compatibility with legacy 74ACT logic systems.
Technical Context
The MC74ACT646DWR2 integrates eight D-type flip-flops per bus side (A and B), enabling synchronous latching of data on LOW-to-HIGH clock transitions at CAB or CBA. Its control logic supports four distinct data-handling modes-real-time A→B, real-time B→A, stored-A→B, and stored-B→A-as defined by combinations of SAB, SBA, DIR, and G inputs.
It uses standard CMOS process with TTL-compatible input thresholds (VIH = 2.0 V min, VIL = 0.8 V max at VCC = 4.5–5.5 V), ensuring interoperability with 5 V TTL systems. Output drive capability is ±24 mA at VCC = 5.5 V, with guaranteed VOL ≤ 0.44 V and VOH ≥ 4.76 V under full load.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | 74ACT - TTL-compatible inputs, CMOS outputs, 5 V operation |
| Supply Voltage Range | 4.5 V to 5.5 V - Matches standard 5 V digital system rails |
| Output Drive | ±24 mA - Sufficient to drive multiple 74-series loads or transmission lines |
| Propagation Delay | Max 16 ns (clock-to-bus) - Enables reliable operation up to ~30 MHz system clocks |
| Input Thresholds | VIH = 2.0 V, VIL = 0.8 V - Ensures noise margin >0.4 V in 5 V TTL environments |
| 3-State Leakage | ±6.0 μA - Minimizes bus contention current when outputs are disabled |
| Operating Temperature | −40 °C to +85 °C - Qualified for industrial ambient conditions |
Pinout & Package
MC74ACT646DWR2 is housed in a 24-pin SOIC wide-body (SOIC-24 WB) package, case 751E, with 0.600-inch body width and 1.27 mm pitch. Pin 1 is marked with a notch or dot; the package is Pb-free and RoHS-compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 23 | CAB, CBA | Asynchronous clock inputs - Load A or B bus data into respective registers on rising edge |
| 2, 22 | SAB, SBA | Transmit/receive select - Enable real-time (SAB/SBA = L) or stored-data (SAB/SBA = H) transfer mode |
| 3, 21 | DIR, G | Direction and output enable - DIR controls A↔B direction; G enables/disables all outputs (active-low) |
| 4–11 | A0–A7 | Data register A inputs/outputs - Bidirectional I/O pins tied to A-side register and bus |
| 14–21 | B0–B7 | Data register B inputs/outputs - Bidirectional I/O pins tied to B-side register and bus |
| 12 | GND | Ground reference - Common return for all signals and power |
| 24 | VCC | Positive supply - 4.5–5.5 V DC power rail for logic and output stages |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent registers | Separate A- and B-side D-flip-flops allow concurrent storage and routing of two data streams |
| Multiplexed real-time/stored transfer | Single device supports both immediate pass-through and clock-synchronized buffered transfer without external logic |
| TTL-compatible inputs | Accepts standard 5 V TTL voltage levels, eliminating level-shifting in mixed-logic systems |
| 3-state output control | G and DIR jointly manage high-impedance state, enabling shared-bus arbitration in multi-device systems |
| Pb-free SOIC-24 package | RoHS-compliant 751E footprint compatible with automated SMT assembly and IPC-7351 standards |
Applications
| Industrial Backplane Interface | Microcontroller Bus Expansion |
|---|---|
Use Scenario: Isolating CPU address/data bus from peripheral modules in programmable logic controllers. IC Role / Device Role / Timing Role: Registered transceiver buffers and synchronizes burst transfers between microcontroller and I/O expansion cards. Use Value: Prevents timing skew across long traces by registering data on clock edges, improving setup/hold margins at 20+ MHz. | Use Scenario: Extending 8-bit parallel bus between MCU and external memory or display controller. IC Role / Device Role / Timing Role: Bidirectional bus repeater with storage capability to decouple master/slave timing domains. Use Value: Enables asynchronous handshaking via SAB/SBA control while maintaining data integrity during clock domain crossings. |
| Legacy System Bus Bridge | Test Equipment Data Path Control |
Use Scenario: Interfacing modern FPGA-based controllers with legacy 74ACT-based subsystems. IC Role / Device Role / Timing Role: Level- and timing-transparent bridge preserving original 74ACT electrical behavior and pinout compatibility. Use Value: Eliminates need for custom adapter PCBs by matching VIH/VIL, propagation delay, and drive strength of legacy parts. | Use Scenario: Routing stimulus/response data between test pattern generator and DUT in automated test equipment. IC Role / Device Role / Timing Role: Controlled-path transceiver enabling deterministic data capture and injection with register hold capability. Use Value: Supports precise timing alignment using CAB/CBA clocks, critical for sub-20 ns test vector resolution. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal registered transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ACT646DW | Identical logic function, same pinout, TI-manufactured; AC characteristics differ slightly (tPLH max 15 ns vs 16 ns) | Valid for drop-in replacement where TI qualification or sourcing diversity is required | Select when TI's qualification documentation or long-term availability assurance is mandated |
| 74ACT646PC | DIP-24 package (not SOIC); identical electrical specs but incompatible footprint and thermal profile | Suitable only for prototyping or through-hole legacy designs; not for SMT production | Choose only for breadboard evaluation or repair of vintage DIP-based systems |
Compared with SN74ACT646DW and 74ACT646PC, the MC74ACT646DWR2 offers identical functional behavior and timing in a Pb-free SOIC-24 package optimized for automated manufacturing, whereas SN74ACT646DW provides second-source assurance and 74ACT646PC serves niche through-hole use cases.
Availability
MC74ACT646DWR2 is available at Aetrix Electronics and suitable for industrial backplane interfaces, microcontroller bus expansion, and legacy system bus bridging requiring stable component supply and long-term manufacturability.
Supply support for MC74ACT646DWR2 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 delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.
The MC74ACT646DWR2 belongs to the 74ACT advanced CMOS logic family, designed specifically to provide TTL-compatible interface capability with improved speed, noise immunity, and drive strength for industrial and embedded control systems.
FAQ
What is the maximum clock frequency supported by MC74ACT646DWR2?
The MC74ACT646DWR2 does not specify a maximum clock frequency directly, but its worst-case propagation delay (clock-to-bus) is 16 ns at VCC = 5.5 V and TA = +85 °C. Assuming minimum pulse width and setup/hold requirements, this supports reliable operation up to approximately 30 MHz in well-designed PCB layouts with controlled impedance and proper termination.
Does MC74ACT646DWR2 support hot insertion or live bus swapping?
No, the MC74ACT646DWR2 is not rated for hot insertion. Its absolute maximum ratings do not include live insertion stress conditions, and the input structure lacks dedicated hot-swap protection circuitry. For live bus applications, external series resistors and TVS diodes are recommended, and system-level testing is required before deployment.
Can MC74ACT646DWR2 operate at 3.3 V supply?
No, MC74ACT646DWR2 is specified only for 4.5 V to 5.5 V operation. Its TTL-compatible inputs require VIH ≥ 2.0 V, and internal logic thresholds are optimized for 5 V rails. Operation below 4.5 V may result in undefined behavior, increased propagation delay, or failure to meet AC timing specifications.
How does the DIR pin affect data flow direction in MC74ACT646DWR2?
In MC74ACT646DWR2, the DIR pin determines the primary data path direction: when DIR = HIGH, data flows from A bus to B bus; when DIR = LOW, data flows from B bus to A bus. This setting interacts with SAB/SBA and G to select among real-time, stored, or isolated transfer modes - DIR alone does not enable outputs (G must be LOW).
Is MC74ACT646DWR2 pin-compatible with MC74AC646DWR2?
Yes, MC74ACT646DWR2 is pin-compatible with MC74AC646DWR2. Both share identical SOIC-24 pinout, register architecture, and control signal definitions (CAB/CBA, SAB/SBA, DIR, G). The key difference is input threshold compatibility: MC74ACT646DWR2 accepts TTL levels, while MC74AC646DWR2 requires CMOS-level inputs (VIH ≥ 3.15 V at VCC = 4.5 V).
MC74ACT646DWR2 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74ACT
- Package/Case:
- 24-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-SOIC
MC74ACT646DWR2 FAQ
1.How can I place an order for MC74ACT646DWR2 through Aetrix?
Please submit a Request for Quotation (RFQ) for MC74ACT646DWR2 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 MC74ACT646DWR2 reliable?
The price and inventory of MC74ACT646DWR2 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC74ACT646DWR2 is usually 5 days.
3.What payment methods are accepted for MC74ACT646DWR2?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC74ACT646DWR2 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC74ACT646DWR2?
MC74ACT646DWR2 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC74ACT646DWR2 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 MC74ACT646DWR2?
For technical support, including MC74ACT646DWR2 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC74ACT646DWR2 requirements.
6.How does Aetrix verify that MC74ACT646DWR2 is sourced from the original manufacturer or authorized distributors?
All MC74ACT646DWR2 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 MC74ACT646DWR2 meets industry standards.
7.What is the process for return or replacement of MC74ACT646DWR2?
All MC74ACT646DWR2 units undergo pre-shipment inspection (PSI). If there is an issue with MC74ACT646DWR2, 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 MC74ACT646DWR2 part is unused and in its original packaging.
Return procedure for MC74ACT646DWR2:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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