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onsemi MC74F640N
- Part No.:
- MC74F640N
- Manufacturer:
- onsemi
- Package:
- -
- Datasheet:
-
MC74F640N.pdf
- Description:
- BUS TRANSCEIVER, F/FAST SERIES,
- Quantity:
- Payment:
- Shipping:
Inventory:3,600
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Product details
Overview
MC74F640N from ON Semiconductor (formerly Motorola) is an octal inverting bus transceiver with 3-state outputs, designed for bidirectional data flow between two 8-bit buses. It features T/R direction control, OE enable, B-port drive capability of 64 mA sink / 15 mA source, and operates at 4.5–5.5 V over 0–70°C ambient range - used in legacy TTL-based system backplanes and memory expansion interfaces.
For engineers reviewing the MC74F640N datasheet, pinout, applications, or equivalent options, key selection considerations include its inverting logic behavior, asymmetric drive strength (B-side vs A-side), 3-state bus isolation during power loss, and FAST Schottky TTL compatibility with legacy 74F logic families.
Technical Context
The MC74F640N implements dual-directional inverting data transfer controlled by separate Transmit/Receive (T/R) and Output Enable (OE) inputs. Its B-port outputs deliver 64 mA sink current and 15 mA source current, while A-port outputs provide 24 mA sink and 3 mA source - enabling asymmetric bus loading management.
It uses high-impedance NPN base inputs (70 µA max input current) to minimize loading on driving sources, and incorporates output clamp diodes (VIK = –1.2 V) and short-circuit protection (IOS up to –225 mA on B ports), all compliant with FAST Schottky TTL electrical standards.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - supports standard 5 V TTL supply with ±10% tolerance |
| Operating Temp | 0 °C to +70 °C - suitable for commercial-grade industrial control backplanes |
| B-port IOL | 64 mA - drives heavy capacitive loads (e.g., long PCB traces or multiple TTL inputs) |
| B-port IOH | 15 mA - sufficient for interfacing with standard TTL or CMOS inputs at logic HIGH |
| tPLH/tPHL | 2.0–8.0 ns - enables high-speed bus arbitration in 74F-class systems |
| IOZH + IIH | ±70 µA - ensures minimal standby current draw when outputs are disabled |
| ESD Rating | 4000 V HBM - meets standard handling requirements for manual assembly environments |
Pinout & Package
MC74F640N is housed in a 20-pin plastic DIP (Dual In-line Package), case 738-03, with 0.3-inch body width and through-hole mounting.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | GND | Power reference ground for all internal logic and I/O stages |
| 2–9 | A0–A7 | Input/output port A - inverted data path toward B bus when T/R = L and OE = L |
| 10 | VCC | +5 V DC supply - powers internal logic and output drivers |
| 11–18 | B0–B7 | Input/output port B - inverted data path toward A bus when T/R = H and OE = L; sinks 64 mA |
| 19 | T/R | Direction control - LOW enables A→B transfer, HIGH enables B→A transfer |
| 20 | OE | Output enable - LOW activates transceiver; HIGH forces all B outputs to high-impedance Z state |
Key Features
| Feature | Design Value |
|---|---|
| Inverting bidirectional data path | Each A↔B transfer inverts logic level - simplifies parity generation or complement-based protocol layers |
| Asymmetric B-port drive strength | 64 mA sink / 15 mA source allows robust driving of unterminated stubs or fan-out to >10 TTL loads |
| High-impedance NPN base inputs | 70 µA max input current reduces loading on upstream drivers - critical in daisy-chained bus topologies |
| Power-loss safe 3-state outputs | B0–B7 enter high-Z if VCC is removed - prevents back-driving or bus contention during hot-swap or brownout |
Applications
| Memory Expansion Interface | Legacy CPU Bus Bridge |
|---|---|
Use Scenario: Connecting additional RAM or ROM modules to an 8-bit microprocessor bus without address decoding overhead. IC Role / Device Role / Timing Role: Bidirectional inverting transceiver isolating main CPU data bus from expansion bus, controlled by RD/WR and direction signals. Use Value: Enables clean signal integrity across extended trace lengths using 64 mA B-port drive, while preventing bus contention during reset via 3-state disable. | Use Scenario: Interfacing disparate 8-bit peripheral buses (e.g., Z80 and 6502 subsystems) requiring voltage-level and logic-polarity alignment. IC Role / Device Role / Timing Role: Logic-level translator and bus direction controller synchronized to shared clock and strobe signals. Use Value: Inversion capability eliminates need for external inverters; asymmetric drive supports mixed-technology bus loading. |
| Digital Test Equipment Backplane | Industrial PLC I/O Module |
Use Scenario: Routing configurable digital stimulus/response signals across modular test instrument slots with hot-plug awareness. IC Role / Device Role / Timing Role: Isolated bidirectional data switch managed by FPGA-controlled T/R and OE lines. Use Value: High-impedance inputs and fail-safe 3-state behavior prevent bus corruption during module insertion/removal. | Use Scenario: Buffering sensor/actuator data between field-side I/O and isolated controller bus in programmable logic controllers. IC Role / Device Role / Timing Role: Electrically isolated bus interface (when paired with optocouplers) handling burst-mode diagnostics and configuration writes. Use Value: 4000 V HBM ESD rating supports rugged factory-floor handling; 0–70°C operation matches industrial ambient requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74F240N | Non-inverting; 15 mA B-port drive only; no T/R pin - requires external direction logic | Lacks integrated direction control; suited for unidirectional or externally managed bidirectional paths | Select when inversion is undesirable and direction is fixed or handled elsewhere |
| MC74F245N | Inverting; identical pinout and drive specs; same FAST TTL family; direct functional replacement | Same use cases - memory expansion, bus bridging, test equipment | Preferred drop-in alternative with identical timing, drive, and logic behavior |
Compared with SN74F240N and MC74F245N, the MC74F640N uniquely integrates T/R control for seamless bidirectional inversion without external gates, while matching MC74F245N's performance - making it optimal for compact, low-component-count bus interface designs.
Availability
MC74F640N is available at Aetrix Electronics and suitable for memory expansion interfaces, legacy CPU bus bridges, and industrial PLC I/O modules requiring stable component supply despite end-of-life status.
Supply support for MC74F640N 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 (formerly Motorola Semiconductor) is a global supplier of high-performance silicon solutions for automotive, industrial, cloud computing, and IoT applications.
The MC74F640N belongs to the FAST Schottky TTL logic family, engineered for high-speed, low-power 5 V digital systems where compatibility with legacy 74F designs and robust bus driving are essential.
FAQ
What logic family does the MC74F640N belong to, and is it compatible with standard TTL?
The MC74F640N is a FAST Schottky TTL device, fully compatible with 74F-series logic levels and timing. It accepts standard TTL input thresholds (VIH = 2.0 V, VIL = 0.8 V) and delivers TTL-compliant VOH/VOL under specified load conditions. Its propagation delay (2.0–8.0 ns) and drive strength align with FAST TTL specifications, ensuring interoperability with existing 74F-based systems without level-shifting circuitry. The MC74F640N maintains this compatibility across its full operating temperature and voltage range.
Does the MC74F640N support true bidirectional data flow without external logic?
Yes, the MC74F640N supports true bidirectional data flow using its dedicated Transmit/Receive (T/R) pin (Pin 19). When OE is active (LOW), asserting T/R = LOW routes inverted data from A0–A7 to B0–B7; asserting T/R = HIGH routes inverted data from B0–B7 to A0–A7. This eliminates the need for external direction-control logic or multiplexers. The MC74F640N thus provides self-contained, pin-driven bidirectionality - a key differentiator from non-inverting or single-direction transceivers like the SN74F240N.
What happens to the B-port outputs of the MC74F640N if VCC is removed during operation?
When VCC is removed, the B-port outputs (B0–B7) of the MC74F640N automatically enter a high-impedance "off" state (Z), as confirmed by design intent and electrical specification. This behavior prevents back-driving or contention on the connected bus, protecting downstream devices during power sequencing, hot-swap events, or brownout conditions. The MC74F640N achieves this via internal circuitry that disables output stages upon loss of supply - a safety feature explicitly documented in its datasheet and function table.
How does the MC74F640N differ from the MC74F245N in functionality and pin compatibility?
The MC74F640N and MC74F245N share identical pinouts, electrical specifications, timing parameters, and inverting bidirectional functionality. Both use the same T/R and OE control scheme and deliver 64 mA sink / 15 mA source on B ports. The MC74F640N is functionally equivalent and pin-compatible with the MC74F245N - confirmed by Motorola's own documentation stating "Inverting Version of F245". No redesign or layout change is required when substituting MC74F640N for MC74F245N in existing circuits.
Is the MC74F640N still manufacturable, and what supply options exist given its Lifetime Buy status?
The MC74F640N was declared Lifetime Buy with last order date 31 March 1999 and last shipment 30 September 1999. It is no longer in production, but Aetrix Electronics maintains verified legacy inventory with full traceability and testing. Supply support includes batch-lot verification, extended warranty coverage, and BOM continuity planning - enabling continued use in maintenance, repair, and obsolescence-managed programs where redesign is impractical. The MC74F640N remains available for qualified industrial and defense sustainment applications.
MC74F640N 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:
- -
MC74F640N FAQ
1.How can I place an order for MC74F640N through Aetrix?
Please submit a Request for Quotation (RFQ) for MC74F640N 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 MC74F640N reliable?
The price and inventory of MC74F640N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC74F640N is usually 5 days.
3.What payment methods are accepted for MC74F640N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC74F640N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC74F640N?
MC74F640N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC74F640N 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 MC74F640N?
For technical support, including MC74F640N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC74F640N requirements.
6.How does Aetrix verify that MC74F640N is sourced from the original manufacturer or authorized distributors?
All MC74F640N 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 MC74F640N meets industry standards.
7.What is the process for return or replacement of MC74F640N?
All MC74F640N units undergo pre-shipment inspection (PSI). If there is an issue with MC74F640N, 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 MC74F640N part is unused and in its original packaging.
Return procedure for MC74F640N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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