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onsemi MC74ACT623N
- Part No.:
- MC74ACT623N
- Manufacturer:
- onsemi
- Package:
- -
- Datasheet:
-
MC74ACT623N.pdf
- Description:
- BUS TRANSCEIVER, ACT SERIES, 1 F
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Inventory:1,780
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Product details
Overview
MC74ACT623N from ON Semiconductor is an octal bidirectional 3-state bus transceiver with TTL-compatible inputs, designed for asynchronous two-way data transfer between parallel buses. It supports A↔B direction control via T/R pin, enables isolation via dual enable pins (GAB/GBA), and delivers ±24 mA drive strength at 5 V. Used in legacy industrial backplanes and microprocessor address/data bus interfaces.
For engineers reviewing the MC74ACT623N datasheet, pinout, applications, or equivalent options, key selection criteria include its 5.0 V ±0.5 V operating range, 7.5 ns max propagation delay (A↔B), 3-state output enable/disable timing, and compatibility with TTL-level control signals in mixed-logic systems.
Technical Context
The MC74ACT623N implements a dual-enable, direction-controlled transceiver architecture where GAB enables B-side outputs and GBA enables A-side outputs, while the T/R pin determines data flow direction (A→B when HIGH, B→A when LOW). All 16 I/Os (A0–A7, B0–B7) are 3-state capable with independent control.
It operates strictly within 4.5 V to 5.5 V supply range per Recommended Operating Conditions, with TTL-compatible input thresholds (VIH = 2.0 V min, VIL = 0.8 V max at VCC = 5.5 V) and guaranteed output drive of –24 mA (IOH) and 24 mA (IOL) under load.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - defines strict 5 V TTL/CMOS interface compliance; operation outside this range invalidates specifications. |
| Propagation Delay | 1.0–8.5 ns (A↔B) - ensures sub-10 ns bus turnaround critical for 20+ MHz synchronous bus handshaking. |
| Output Drive | ±24 mA per pin - supports direct driving of 10–15 TTL loads or termination-matched stubs without buffers. |
| Input Thresholds | VIH ≥ 2.0 V, VIL ≤ 0.8 V @ 5.5 V - guarantees interoperability with standard TTL logic families and 5 V microcontrollers. |
| 3-State Enable/Disable | tPZH/tPHZ ≤ 11.0 ns - enables fast bus arbitration and prevents contention during mode switching. |
| Quiescent Current | ICC ≤ 80 µA - allows integration into low-power standby modes without significant leakage impact. |
Pinout & Package
MC74ACT623N uses a 20-pin plastic DIP package (Case 738–03, N suffix), with 0.3-inch width and standard through-hole mounting. Pin 1 is top-left corner, pin 20 bottom-right.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (GAB) | B-Side Output Enable | Active-HIGH control: drives B0–B7 outputs to high-impedance when LOW; must be synchronized with T/R for clean bus isolation. |
| 2–9 (B0–B7) | Side-B Bidirectional I/O | 3-state pins supporting data reception (input) or transmission (output) depending on T/R and GAB state. |
| 10 (GND) | Ground Reference | Primary signal return path; requires low-inductance connection to minimize ground bounce during simultaneous switching. |
| 11 (T/R) | Direction Control | HIGH = A→B, LOW = B→A; edge-sensitive timing requires stable level before data launch to avoid metastability. |
| 12–19 (A0–A7) | Side-A Bidirectional I/O | 3-state pins mirroring B-side behavior; driven by same internal transceiver core with independent enable control. |
| 20 (VCC) | Power Supply | +5 V DC supply; requires local 0.1 µF ceramic decoupling adjacent to pin to suppress switching noise. |
Key Features
| Feature | Design Value |
|---|---|
| TTL-Compatible Inputs | VIH/VIL thresholds match standard TTL logic, enabling direct interfacing with 74LS/74F families without level-shifting. |
| Dual Independent Enables | GAB and GBA allow asymmetric bus control-e.g., isolate B-bus while keeping A-bus active for diagnostics or monitoring. |
| Guaranteed 3-State Timing | tPZH/tPLZ and tPHZ/tPLZ specified over full temperature range (–40°C to +85°C), ensuring deterministic bus release in industrial environments. |
| High Sink/Source Capability | 24 mA drive supports fanout to multiple TTL inputs or resistive termination, reducing need for external drivers in backplane designs. |
Applications
| Industrial Backplane Interface | Microcontroller Address/Data Bus Extension |
|---|---|
Use Scenario: Interfacing multiple ISA-style peripheral cards to a central controller in factory automation PLC racks. IC Role / Device Role / Timing Role: Bidirectional transceiver managing shared 8-bit data/address lines between CPU and expansion slots, controlled by board-select and direction strobes. Use Value: ±24 mA drive ensures signal integrity across 15 cm backplane traces; 8.5 ns max tPLH enables 12 MHz bus clocking with setup margin. | Use Scenario: Extending Z80 or 8085 CPU address/data bus to external RAM or I/O peripherals in embedded instrumentation. IC Role / Device Role / Timing Role: Isolating and routing multiplexed AD0–AD7 lines between CPU and memory chips using T/R and GAB/GBA for cycle-specific direction control. Use Value: Guaranteed 3-state disable time (tPHZ ≤ 11 ns) prevents bus contention during memory read/write transitions. |
| Legacy Computer System Upgrade | Test Equipment Signal Routing |
Use Scenario: Retrofitting TTL-based logic analyzers or vintage computer motherboards requiring 5 V bus bridging. IC Role / Device Role / Timing Role: Replacing obsolete 74LS623 with pin-compatible AC/ACT-speed upgrade while retaining existing PCB layout and firmware. Use Value: Identical pinout and function with faster propagation (vs LS) and lower ICC reduce power and improve timing margins. | Use Scenario: Configurable signal path switching in automated test equipment (ATE) fixture controllers. IC Role / Device Role / Timing Role: Dynamically reconfiguring DUT interface connections between stimulus and measurement channels using microcontroller-driven T/R/GAB. Use Value: Dual enable pins allow independent channel gating, enabling multi-DUT parallel testing without hardware reconfiguration. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bidirectional transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ACT623N | Identical electrical specs, pinout, and timing; manufactured by Texas Instruments with same AC/ACT family characterization. | No functional difference; validated for identical legacy 5 V bus systems and replacement scenarios. | Select SN74ACT623N when TI-sourced parts are required for supply chain diversification or qualification continuity. |
| 74LCX623M | Lower voltage operation (2.5 V–3.6 V), higher speed (tPLH ≤ 5.5 ns), but incompatible 5 V TTL input thresholds and reduced drive (±24 mA only at 3.3 V). | Requires level translation for 5 V systems; suited for newer low-voltage mixed-signal boards, not drop-in replacement. | Choose 74LCX623M only for new 3.3 V designs where power efficiency and speed outweigh legacy compatibility needs. |
Compared with SN74ACT623N, MC74ACT623N offers identical performance and fit but differs in manufacturer qualification and traceability; versus 74LCX623M, it provides guaranteed 5 V TTL interoperability and robust drive at legacy supply rails, making it irreplaceable in fielded 5 V infrastructure.
Availability
MC74ACT623N is available at Aetrix Electronics and suitable for industrial backplane interfaces, microcontroller bus extension, legacy computer upgrades, and test equipment signal routing requiring stable component supply across extended product lifecycles.
Supply support for MC74ACT623N 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
ON Semiconductor is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.
The MC74ACT623N belongs to ON Semiconductor's legacy 74ACT logic family, engineered specifically for high-speed, 5 V TTL-compatible bus interfacing in industrial control and retro-computing systems where reliability and long-term availability are critical.
FAQ
What is the recommended operating voltage range for the MC74ACT623N?
The MC74ACT623N is specified for operation only between 4.5 V and 5.5 V DC. Operation below 4.5 V risks failure to meet VIH/VIL thresholds and output drive guarantees; above 5.5 V exceeds absolute maximum ratings and may cause permanent damage. The MC74ACT623N does not support 3.3 V or mixed-voltage operation without external level translation.
How does the T/R pin control data direction in the MC74ACT623N?
In the MC74ACT623N, the T/R pin is a static direction selector: when HIGH, data flows from A-side inputs (A0–A7) to B-side outputs (B0–B7); when LOW, data flows from B-side inputs to A-side outputs. This control is asynchronous and must be stable before valid data is applied to avoid bus contention or undefined states.
Can the MC74ACT623N be used with 3.3 V logic systems?
No-the MC74ACT623N is not 3.3 V compatible. Its inputs require TTL-level thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V at 5.5 V), and its outputs swing rail-to-rail at 5 V. Direct connection to 3.3 V systems risks overvoltage damage to downstream receivers and violates input voltage limits. Level-shifting circuitry is mandatory for interoperability with 3.3 V logic.
What is the maximum capacitive load the MC74ACT623N can drive reliably?
The MC74ACT623N AC characteristics (propagation delay, enable/disable timing) are characterized at CL = 50 pF. While it can drive heavier loads, exceeding 50 pF increases propagation delay nonlinearly and may degrade timing margins. For reliable operation beyond 50 pF, derating analysis or buffer insertion is recommended-especially in MC74ACT623N-based backplane designs with distributed capacitance.
Does the MC74ACT623N support hot-swap or live-insertion capability?
No-the MC74ACT623N lacks built-in hot-swap protection features such as power-up sequencing control, Ioff partial power-down, or bus-fault tolerance. Applying signal inputs before VCC stabilization or during power ramp may cause latch-up or excessive ICC. System-level protection (e.g., series resistors, power sequencing ICs) is required for safe hot-swap use of the MC74ACT623N.
MC74ACT623N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Logic Type:
- -
- Number of Elements:
- -
- Number of Bits per Element:
- -
- Input Type:
- -
- Output Type:
- -
- Current - Output High, Low:
- -
- Voltage - Supply:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
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- Mounting Type:
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- Supplier Device Package:
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MC74ACT623N FAQ
1.How can I place an order for MC74ACT623N through Aetrix?
Please submit a Request for Quotation (RFQ) for MC74ACT623N 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 MC74ACT623N reliable?
The price and inventory of MC74ACT623N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC74ACT623N is usually 5 days.
3.What payment methods are accepted for MC74ACT623N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC74ACT623N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC74ACT623N?
MC74ACT623N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC74ACT623N 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 MC74ACT623N?
For technical support, including MC74ACT623N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC74ACT623N requirements.
6.How does Aetrix verify that MC74ACT623N is sourced from the original manufacturer or authorized distributors?
All MC74ACT623N 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 MC74ACT623N meets industry standards.
7.What is the process for return or replacement of MC74ACT623N?
All MC74ACT623N units undergo pre-shipment inspection (PSI). If there is an issue with MC74ACT623N, 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 MC74ACT623N part is unused and in its original packaging.
Return procedure for MC74ACT623N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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