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onsemi MC74AC652N
- Part No.:
- MC74AC652N
- Manufacturer:
- onsemi
- Package:
- -
- Datasheet:
-
MC74AC652N.pdf
- Description:
- REGISTERED BUS TRANSCEIVER
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Product details
Overview
MC74AC652N from ON Semiconductor is an octal registered bus transceiver with non-inverting 3-state outputs, designed for bidirectional data flow between A and B buses in TTL/CMOS systems. It features independent A/B registers, real-time and stored-data multiplexing, 24 mA output drive, and operates at 2.0–6.0 V supply. Used in backplane interface logic and memory address/data bus isolation.
For engineers reviewing the MC74AC652N datasheet, pinout, applications, or equivalent options, this page provides verified functional role, timing behavior, register control logic, 3-state enable sequencing, and direct replacement guidance for legacy DIP-24 logic designs.
Technical Context
The MC74AC652N implements dual 8-bit D-type flip-flop registers clocked by separate CAB (A→B) and CBA (B→A) inputs, enabling asynchronous storage of data from either bus. Its SAB/SBA select lines determine real-time or registered transfer mode, while GAB/GBA independently enable A→B and B→A 3-state outputs.
It supports mixed-voltage operation (2.0–6.0 V), delivers ±24 mA per output at VCC = 5.0 V, and exhibits propagation delays as low as 1.5 ns (tPHL, A→B path, 5 V). Input thresholds are CMOS-compatible (VIH = 2.1 V min @ 3 V), and it meets industrial temperature range (−40°C to +85°C).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Function | Octal registered transceiver with independent A/B storage and non-inverting 3-state outputs |
| Supply Voltage Range | 2.0 V to 6.0 V - supports mixed-voltage system interfacing and 3.3 V/5 V coexistence |
| Output Drive | ±24 mA per pin - sufficient to drive standard TTL loads and multiple CMOS inputs without buffering |
| Propagation Delay | 1.5 ns min (tPHL, A→B path, 5 V) - enables high-speed bus handshaking in real-time transfer mode |
| Operating Temperature | −40°C to +85°C - qualified for industrial-grade embedded control and instrumentation applications |
| Input Thresholds | VIH = 2.1 V min @ 3.0 V - ensures reliable CMOS-level recognition across full VCC range |
| 3-State Enable Logic | GAB and GBA are active-low - allows independent direction control and bus contention avoidance |
Pinout & Package
MC74AC652N is housed in a 300-mil 24-pin plastic dual-in-line package (PDIP-24, Case 724), with 0.3-inch width and through-hole mounting. Pin 1 is top-left corner (notch-up orientation); VCC on pin 24, GND on pin 12.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A7 | Data Register A Inputs / Outputs | Bi-directional I/O pins for A bus; register input when clocked, output when enabled and not isolated |
| B0–B7 | Data Register B Inputs / Outputs | Bi-directional I/O pins for B bus; register input when clocked, output when enabled and not isolated |
| CAB | Register Clock A→B | LOW-to-HIGH transition loads A-bus data into A register and/or transfers to B bus per SAB/GAB state |
| CBA | Register Clock B→A | LOW-to-HIGH transition loads B-bus data into B register and/or transfers to A bus per SBA/GBA state |
| SAB | Transfer Select A→B | Active-high selects real-time (SAB = H) or registered (SAB = L) A→B data path |
| SBA | Transfer Select B→A | Active-high selects real-time (SBA = H) or registered (SBA = L) B→A data path |
| GAB | Output Enable A→B | Active-low enables A→B outputs; high-Z when GAB = H blocks A-bus drivers |
| GBA | Output Enable B→A | Active-low enables B→A outputs; high-Z when GBA = H blocks B-bus drivers |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent registers | Enables simultaneous A→B and B→A data staging without bus conflict or shared clock dependency |
| Multiplexed real-time/stored transfer | Per-pin SAB/SBA control allows dynamic switching between live bus pass-through and registered data delivery |
| Non-inverting 3-state outputs | Preserves signal polarity during bidirectional transfer and eliminates need for external inverters in level-sensitive systems |
| CMOS-compatible input thresholds | VIH/VIL defined across 2.0–6.0 V range - ensures interoperability with both 3.3 V and 5 V logic families |
| Industrial temperature rating | Validated operation from −40°C to +85°C - suitable for uncontrolled ambient environments in factory automation |
Applications
| Backplane Data Routing | Memory Bus Isolation |
|---|---|
Use Scenario: Isolating CPU address/data bus from peripheral expansion slots in modular industrial controllers. IC Role / Device Role / Timing Role: Bidirectional registered transceiver managing time-aligned data exchange between master and slave modules via shared backplane. Use Value: Prevents bus contention during hot-swap events using independent GAB/GBA enables and register hold capability. |
Use Scenario: Separating microcontroller data bus from SRAM or flash memory in space-constrained embedded systems. IC Role / Device Role / Timing Role: Registered buffer providing setup/hold margin for memory read/write cycles while decoupling timing domains. Use Value: Enables reliable 5 V memory access from 3.3 V MCU via voltage-tolerant inputs and 24 mA drive strength. |
| Legacy System Bus Extension | Test Equipment Signal Switching |
Use Scenario: Extending 8-bit ISA-style data paths in retro-computing or diagnostic hardware with modern PCB layout. IC Role / Device Role / Timing Role: Pin-compatible octal transceiver replacing obsolete 74LS652 in through-hole designs requiring register retention. Use Value: Maintains identical PDIP-24 footprint and logic function while improving noise immunity and reducing power consumption. |
Use Scenario: Configurable signal routing between DUT I/O ports and measurement instruments in automated test fixtures. IC Role / Device Role / Timing Role: Programmable bidirectional switch with register hold for capturing transient signals before analysis. Use Value: Captures stable snapshot of bus state using CAB/CBA clocks, then forwards via SAB/SBA-controlled path for synchronized readout. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal registered transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MC74ACT652N | TTL-compatible inputs (VIH = 2.0 V min @ 5 V); otherwise identical pinout, timing, and register architecture | Required when interfacing with legacy 5 V TTL sources where AC-series input thresholds may cause marginal recognition | Select MC74ACT652N only if driving inputs originate from standard TTL logic; otherwise MC74AC652N offers superior noise margin in mixed CMOS systems. |
| SN74ABT652N | Higher drive (±64 mA), faster tPLH/tPHL (≤3.5 ns @ 5 V), but requires 4.5–5.5 V only and lacks 2.0–3.6 V support | Used in high-speed backplanes where timing budget is critical and supply is strictly 5 V | Choose SN74ABT652N only when speed >12 ns propagation delay is mandatory and 5 V-only operation is acceptable. |
Compared with MC74ACT652N and SN74ABT652N, the MC74AC652N uniquely supports wide-supply operation (2.0–6.0 V) while maintaining industrial temperature range and legacy PDIP-24 compatibility - making it optimal for voltage-flexible, long-lifecycle industrial upgrades.
Availability
MC74AC652N is available at Aetrix Electronics and suitable for backplane routing, memory bus isolation, legacy system extension, test equipment signal switching, and industrial controller bus management requiring stable component supply over extended production lifecycles.
Supply support for MC74AC652N 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 (now onsemi) is a global semiconductor supplier specializing in energy-efficient power management, analog, logic, and discrete devices for automotive, industrial, and cloud infrastructure markets.
The MC74AC652N belongs to the 74AC logic family, engineered for high-speed, low-power CMOS operation with TTL-compatible drive strength - targeting industrial control, instrumentation, and legacy system modernization where reliability and long-term availability are critical.
FAQ
What is the primary function of the MC74AC652N?
The MC74AC652N is an octal registered bus transceiver that enables bidirectional data transfer between two 8-bit buses (A and B) with independent storage registers, real-time or registered path selection, and 3-state output control. Its core function is to isolate, synchronize, and route digital data in systems requiring bus arbitration or timing margin - such as industrial controllers and memory interfaces. The MC74AC652N achieves this using separate CAB/CBA clocks and SAB/SBA select lines.
Does the MC74AC652N support 3.3 V operation?
Yes, the MC74AC652N supports 3.3 V operation within its specified supply range of 2.0 V to 6.0 V. At VCC = 3.3 V, it guarantees VIH ≥ 1.5 V and VIL ≤ 0.9 V, ensuring robust CMOS-level compatibility with 3.3 V microcontrollers and FPGAs. Output drive remains ±24 mA, and propagation delays are characterized down to 3.0 V, making the MC74AC652N suitable for mixed-voltage board designs without level shifters.
How does the MC74AC652N handle bus contention?
The MC74AC652N prevents bus contention through independent 3-state output enables: GAB controls A→B drivers and GBA controls B→A drivers, both active-low. When either enable is high, its respective outputs enter high-impedance state - physically disconnecting that bus segment. Combined with register staging (via CAB/CBA), this allows safe handshaking: one side can drive while the other samples, or both sides can hold data without conflict. This behavior is explicitly defined in the Function Table of the MC74AC652N datasheet.
What is the difference between MC74AC652N and MC74ACT652N?
The MC74AC652N and MC74ACT652N share identical pinout, register architecture, timing, and packaging, but differ in input threshold compatibility: the MC74ACT652N has TTL-compatible inputs (VIH = 2.0 V min @ 5 V), while the MC74AC652N uses pure CMOS thresholds (VIH = 2.1 V min @ 3 V, scaling with VCC). Thus, MC74ACT652N is preferred for interfacing with legacy 5 V TTL sources, whereas MC74AC652N offers better noise immunity in CMOS-dominant systems. Both are drop-in replacements in PDIP-24 sockets.
Is the MC74AC652N RoHS compliant?
Yes, the MC74AC652N is available in Pb-free (RoHS-compliant) packaging, as confirmed in the official ON Semiconductor documentation. The device marking and ordering information specify Pb-free variants, and the datasheet states that "Specifications herein apply to both standard and Pb-free devices." Aetrix Electronics supplies only RoHS-compliant MC74AC652N units meeting JEDEC J-STD-609 Category 3 requirements, with full material declarations available upon request.
MC74AC652N 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:
- -
- Mounting Type:
- -
- Supplier Device Package:
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MC74AC652N FAQ
1.How can I place an order for MC74AC652N through Aetrix?
Please submit a Request for Quotation (RFQ) for MC74AC652N 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 MC74AC652N reliable?
The price and inventory of MC74AC652N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC74AC652N is usually 5 days.
3.What payment methods are accepted for MC74AC652N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC74AC652N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC74AC652N?
MC74AC652N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC74AC652N 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 MC74AC652N?
For technical support, including MC74AC652N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC74AC652N requirements.
6.How does Aetrix verify that MC74AC652N is sourced from the original manufacturer or authorized distributors?
All MC74AC652N 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 MC74AC652N meets industry standards.
7.What is the process for return or replacement of MC74AC652N?
All MC74AC652N units undergo pre-shipment inspection (PSI). If there is an issue with MC74AC652N, 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 MC74AC652N part is unused and in its original packaging.
Return procedure for MC74AC652N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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