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Texas Instruments CD74FCT653M
- Part No.:
- CD74FCT653M
- Manufacturer:
- Texas Instruments
- Package:
- -
- Datasheet:
-
CD74FCT653M.pdf
- Description:
- BUS TRANSCEIVER, FCT SERIES
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Product details
Overview
CD74FCT653M from Texas Instruments is a BiCMOS octal bus transceiver and register with open-collector outputs on the A bus and 3-state outputs on the B bus, supporting real-time or stored-data multiplexing in 5-V digital systems. It features inverted logic, 64-mA sink capability per A-side output, 80-MHz clock frequency, and operation from 0°C to 70°C - used in legacy backplane data routing and buffered address/data bus isolation.
For engineers reviewing the CD74FCT653M datasheet, CD74FCT653M pinout, CD74FCT653M application, or CD74FCT653M equivalent, key selection criteria include its dual-register architecture, independent OE/S control per bus, open-collector vs. 3-state output partitioning, and BiCMOS EMI-reduction design limiting VOH to 3.7 V.
Technical Context
The CD74FCT653M integrates two independent D-type flip-flop registers (one per bus), each with dedicated clock (CLKAB/CLKBA), select (SAB/SBA), and output-enable (OEAB/OEBA) controls. Its BiCMOS process combines bipolar pull-downs for high sink current and CMOS input stages for low quiescent power.
Real-time transfer bypasses internal registers when OEAB and OEBA are simultaneously active; stored-data mode uses low-to-high clock transitions to latch A/B bus data regardless of OE/S states. Output voltage swing is clamped to 0–3.7 V via internal diode drops, reducing VCC bounce and EMI during simultaneous switching.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.75 V to 5.25 V - ensures compatibility with TTL/5-V CMOS logic families and stable noise margins. |
| Max Clock Frequency | 80 MHz - supports high-speed synchronous bus arbitration in legacy computing and industrial control backplanes. |
| A-Bus Output Type | Open-collector - enables wired-AND bus sharing and level translation when pulled up externally. |
| B-Bus Output Type | 3-state - allows bidirectional B-bus connection without contention in shared-memory or peripheral interfaces. |
| Sink Current (A-side) | 64 mA per pin - drives heavy capacitive loads or multiple TTL inputs while maintaining VOL ≤ 0.55 V. |
| Propagation Delay | 6–9 ns (tpd, tPLZ, tPZL) - guarantees timing closure in fast 5-V system buses with setup/hold times as low as 4 ns/2 ns. |
| Operating Temperature | 0°C to 70°C - qualified for commercial-grade embedded systems and non-automotive industrial equipment. |
Pinout & Package
CD74FCT653M is housed in a 24-pin SOIC (DW) package with 300-mil body width and standard gull-wing lead form. Pin spacing is 0.050 inch (1.27 mm), compatible with IPC-7351B SOIC-24 footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (CLKAB) | A-to-B register clock | Low-to-high edge latches A-bus data into B-side storage register; functional even when OEBA is inactive. |
| 2 (SAB) | A-to-B select control | Low = real-time A→B transfer; high = stored-A→B transfer; eliminates multiplexer glitch during mode transition. |
| 3 (OEAB) | A-to-B output enable | Low enables A-bus open-collector outputs; high places A pins in high-impedance state (no pull-up required). |
| 4–11 (A1–A8) | A-bus I/O terminals | Inverting open-collector outputs; inputs always enabled for storage - no direction control needed. |
| 12 (GND) | Ground reference | Primary return path for all internal logic and output currents; must be low-inductance for noise control. |
| 13 (VCC) | Power supply | +5-V supply; BiCMOS design limits VOH swing to ~3.7 V, reducing simultaneous switching noise. |
| 14–21 (B1–B8) | B-bus I/O terminals | Inverting 3-state outputs; direction determined by OEBA and SBA - not by external direction pin. |
| 22 (OEBA) | B-to-A output enable | Low enables B-bus 3-state outputs; high disables B outputs, isolating B bus from A bus. |
| 23 (SBA) | B-to-A select control | Low = real-time B→A transfer; high = stored-B→A transfer; synchronized with CLKBA for glitch-free switching. |
| 24 (CLKBA) | B-to-A register clock | Low-to-high edge latches B-bus data into A-side storage register; operates independently of CLKAB. |
Key Features
| Feature | Design Value |
|---|---|
| Independent dual-register architecture | Enables concurrent storage of A-bus and B-bus data, allowing asynchronous read/write operations across isolated buses. |
| BiCMOS output stage | Delivers 64-mA sink current with controlled edge rates, minimizing ground bounce and EMI in dense PCB layouts. |
| Glitch-free select control | SAB/SBA circuitry prevents transient bus contention during real-time ↔ stored-data mode transitions - no external debounce needed. |
| Inverted output logic | Reduces external inversion requirements in parity checking, address decoding, and complement-based bus protocols. |
| Input/output isolation from VCC | Prevents latch-up under overvoltage or hot-insertion conditions; SCR-latch-up-resistant process rated to 6-V absolute max. |
Applications
| Legacy Backplane Data Routing | Buffered Address Bus Isolation |
|---|---|
Use Scenario: Bidirectional data exchange between CPU and memory modules on ISA or VME-style backplanes with mixed load capacitance. IC Role / Device Role / Timing Role: Octal transceiver/register providing registered A↔B bus transfer with independent clocking and select control to eliminate arbitration glitches. Use Value: Enables deterministic timing at 80 MHz while suppressing EMI via 3.7-V VOH clamp and controlled slew rates - critical for signal integrity in multi-slot chassis. |
Use Scenario: Isolating microprocessor address lines from peripheral decoders during DMA cycles to prevent bus contention. IC Role / Device Role / Timing Role: Inverting buffer with 3-state B outputs and open-collector A outputs, allowing dynamic bus ownership handoff between CPU and DMA controller. Use Value: 64-mA sink capability drives long traces and multiple decoder inputs; independent OEAB/OEBA permits precise timing of bus release and acquisition. |
| Dual-Mode Memory Interface | Real-Time + Stored Data Multiplexing |
Use Scenario: Supporting both direct memory access and shadow RAM updates in industrial PLC I/O modules with deterministic latency. IC Role / Device Role / Timing Role: Registering address/data on either bus using CLKAB/CLKBA, then transferring stored values synchronously to downstream logic. Use Value: Eliminates need for external latches; real-time transfer mode allows immediate response to interrupt-driven I/O, while stored mode ensures atomic memory writes. |
Use Scenario: Merging sensor telemetry (real-time) with configuration parameters (stored) onto a single serial interface bus in test equipment. IC Role / Device Role / Timing Role: Multiplexing live A/B bus data or preloaded register contents based on SAB/SBA control - no external logic required. Use Value: Glitch-free select transition avoids spurious bus states; BiCMOS drive strength maintains signal fidelity across noisy factory-floor environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver and register applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74FCT653N | DIP-24 package only; identical electrical specs and pinout but higher thermal resistance (67°C/W vs. 46°C/W). | Preferred for through-hole prototyping or legacy board rework where SOIC reflow is unavailable. | Select SN74FCT653N only if manual soldering or socket-based testing is required; same logic function and timing. |
| 74AC653SCX | CMOS-only process; 24-mA sink (vs. 64-mA); no open-collector A outputs - all outputs are 3-state; VOH = VCC. | Lower drive strength suits light-load applications; lacks wired-AND capability and EMI suppression of BiCMOS swing limiting. | Choose 74AC653SCX only for low-power, low-noise systems with minimal fanout - not drop-in compatible due to output structure and drive mismatch. |
Compared with CD74FCT653M, SN74FCT653N offers identical functionality in DIP format but requires greater thermal margin, while 74AC653SCX trades BiCMOS drive and EMI control for lower ICC and full 3-state symmetry - neither is pin-compatible nor functionally interchangeable without layout and timing validation.
Availability
CD74FCT653M is available at Aetrix Electronics and suitable for legacy system repair, industrial control retrofitting, and military/aerospace obsolescence mitigation requiring stable component supply and traceable sourcing.
Supply support for CD74FCT653M 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
Texas Instruments is a U.S.-based semiconductor company founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The CD74FCT653M belongs to TI's 74FCT family of BiCMOS logic devices, designed specifically for high-speed, low-noise 5-V digital systems requiring robust drive strength and EMI control in commercial-temperature environments.
FAQ
What is the primary function of the CD74FCT653M in a digital system?
The CD74FCT653M serves as an octal bus transceiver and register that enables bidirectional data flow between two 8-bit buses (A and B) with optional real-time or stored-data transfer modes. It uses independent clock, select, and output-enable controls to manage timing and direction without external logic. The CD74FCT653M integrates D-type flip-flops on both sides, supports open-collector A outputs and 3-state B outputs, and is optimized for noise-sensitive 5-V applications where EMI reduction and high sink current are critical.
Does the CD74FCT653M support true bidirectional data transfer without external direction control?
Yes - the CD74FCT653M achieves bidirectional operation through its dual-control architecture: OEAB and OEBA independently enable A→B or B→A paths, while SAB and SBA select between real-time or stored data sources. No external direction pin is needed because directionality is determined by which OE and S signals are asserted. The CD74FCT653M also allows simultaneous A→B and B→A stored-data transfer when both CLKAB and CLKBA trigger on the same edge, making it suitable for ping-pong buffering applications.
Why does the CD74FCT653M limit its output high voltage to 3.7 V instead of VCC?
The CD74FCT653M uses a BiCMOS output stage with internal diode drops that clamp VOH to approximately two diode drops below VCC (≈3.7 V at 5 V). This intentional voltage swing limitation reduces power-bus ringing, minimizes VCC and ground bounce during simultaneous switching, and lowers EMI - especially important in dense backplane or multi-drop bus environments. The CD74FCT653M maintains full TTL-compatible logic levels (VIH = 2 V, VIL = 0.8 V), so the reduced VOH does not impair interfacing with standard 5-V receivers.
Can the CD74FCT653M operate with input voltages above VCC or below GND?
No - the CD74FCT653M has absolute maximum ratings specifying VI must remain within 0 V to VCC (–0.5 V to 6 V), and input clamp current is limited to –20 mA. Exceeding these ranges risks permanent damage. All unused inputs must be tied to VCC or GND to prevent floating nodes and ensure predictable operation. The CD74FCT653M does not support overvoltage-tolerant or negative-voltage inputs; its design assumes clean 5-V TTL/CMOS signaling within recommended operating conditions.
Is the CD74FCT653M still in active production, and what is its lifecycle status?
The CD74FCT653M is marked as OBSOLETE by Texas Instruments per official packaging documentation, meaning TI has discontinued its production. However, Aetrix Electronics maintains verified legacy inventory with full traceability and extended availability support for ongoing maintenance and repair programs. The CD74FCT653M remains suitable for obsolescence management in deployed systems where form-fit-function replacement is required, and Aetrix provides lifecycle coordination to mitigate supply risk for long-term production needs.
CD74FCT653M Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- 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:
- -
CD74FCT653M FAQ
1.How can I place an order for CD74FCT653M through Aetrix?
Please submit a Request for Quotation (RFQ) for CD74FCT653M 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 CD74FCT653M reliable?
The price and inventory of CD74FCT653M are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD74FCT653M is usually 5 days.
3.What payment methods are accepted for CD74FCT653M?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD74FCT653M transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD74FCT653M?
CD74FCT653M orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD74FCT653M 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 CD74FCT653M?
For technical support, including CD74FCT653M datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD74FCT653M requirements.
6.How does Aetrix verify that CD74FCT653M is sourced from the original manufacturer or authorized distributors?
All CD74FCT653M 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 CD74FCT653M meets industry standards.
7.What is the process for return or replacement of CD74FCT653M?
All CD74FCT653M units undergo pre-shipment inspection (PSI). If there is an issue with CD74FCT653M, 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 CD74FCT653M part is unused and in its original packaging.
Return procedure for CD74FCT653M:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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