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Texas Instruments CY74FCT646TQCTG4
- Part No.:
- CY74FCT646TQCTG4
- Manufacturer:
- Texas Instruments
- Package:
- 24-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
CY74FCT646TQCTG4.pdf
- Description:
- IC TXRX NON-INVERT 5.25V 24SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,245
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Product details
Overview
CY74FCT646TQCTG4 from Texas Instruments is an 8-bit registered transceiver with 3-state outputs, designed for bidirectional data routing between A and B buses in high-noise industrial and telecom backplane systems. It features independent A/B registers, dual clock inputs (CPAB/CPBA), direction control (DIR), output-enable (G), and data-source-select inputs (SAB/SBA). Its 64-mA sink / 32-mA source drive supports robust TTL-level interfacing.
For engineers reviewing the CY74FCT646TQCTG4 datasheet, CY74FCT646TQCTG4 pinout, CY74FCT646TQCTG4 application, or CY74FCT646TQCTG4 equivalent, key selection criteria include registered bus isolation capability, Ioff partial-power-down support, edge-rate controlled switching for EMI reduction, and compatibility with legacy FCT logic families.
Technical Context
This device implements dual 8-bit D-type flip-flop registers-one per bus-with asynchronous 3-state output control. Data latching occurs on low-to-high transitions of CPAB (A→B) or CPBA (B→A), while DIR selects real-time or stored data path direction and G enables/disables outputs.
It integrates edge-rate control circuitry to limit slew rate, reducing simultaneous switching noise. Ioff protection disables outputs when VCC = 0 V, preventing backflow current during partial power-down-critical for hot-swap and mixed-voltage system designs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Bus width | 8-bit bidirectional registered transceiver with independent A and B registers |
| Output drive | 64 mA sink / 32 mA source at VCC = 4.75–5.25 V - drives heavy capacitive loads and multiple TTL inputs |
| Propagation delay | 1.5–9 ns (A↔B path) - supports >100 MHz bus operation with tight timing margins |
| Ioff support | Active at VCC = 0 V; limits Ioff to ±1 µA - enables safe partial-power-down in modular systems |
| Supply voltage | 4.75–5.25 V - tightly regulated 5-V operation compatible with legacy TTL and FCT logic |
| ESD rating | 2000-V HBM, 200-V MM, 1000-V CDM - meets industrial-grade reliability requirements |
| Operating temperature | –40°C to +85°C - qualified for commercial/industrial ambient environments |
Pinout & Package
Package: 24-pin QSOP (DBQ), body size 8.65 mm × 3.9 mm, pitch 0.635 mm, RoHS-compliant NiPdAu lead finish, MSL Level-2-260°C-1 year.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8, 17, 18, 19, 20, 21, 22, 23, 24 | A1–A8, B1–B8 | Bi-directional data terminals: A pins serve as register A inputs / register B outputs; B pins serve as register B inputs / register A outputs |
| 9, 10 | CPAB, CPBA | Independent clock inputs: CPAB clocks data from A to B register; CPBA clocks data from B to A register |
| 11, 12 | SAB, SBA | Data-source select: SAB controls whether A-bus output reflects real-time B input or stored B register; SBA controls B-bus output source |
| 13, 14 | DIR, G | Direction and output-enable: DIR sets data flow direction (A→B or B→A); G enables/disables all 3-state outputs |
| 15, 16 | GND, VCC | Power supply reference and 5-V supply rail - decoupling required within 1 cm of pins |
Key Features
| Feature | Design Value |
|---|---|
| Edge-rate controlled outputs | Reduced dV/dt minimizes ground bounce and crosstalk in dense PCB layouts |
| Independent A/B register storage | Enables concurrent capture of A and B bus states without contention or arbitration logic |
| Ioff partial-power-down | Prevents back-current flow when VCC is off - essential for hot-plug and power-gated subsystems |
| Matched rise/fall times | Ensures symmetrical signal integrity and reduces jitter in clocked data paths |
| FCT/F logic compatibility | Pin- and function-compatible with industry-standard 74FCT646 devices - drop-in replacement for legacy designs |
Applications
| Telecom Backplane Interface | Industrial PLC I/O Module |
|---|---|
|
Use Scenario: Bidirectional data exchange between CPU module and field I/O cards across a 24-pin parallel backplane with long trace lengths and shared ground planes. IC Role / Device Role / Timing Role: Registered transceiver buffering and isolating A/B buses; stores data on clock edges to synchronize asynchronous modules. Use Value: Edge-rate control suppresses simultaneous switching noise; Ioff prevents backfeed during card hot-swap; 64-mA drive overcomes 50-pF trace capacitance. |
Use Scenario: Isolating microcontroller GPIO from noisy 24-V digital input/output circuits in programmable logic controllers. IC Role / Device Role / Timing Role: Bus transceiver with register hold capability - captures sensor status before CPU read, and latches actuator commands before execution. Use Value: Independent A/B registers enable deterministic sampling; 3-state outputs prevent bus contention during reset; TTL-compatible thresholds simplify level translation. |
| Test Equipment Digital Pattern Generator | Military Avionics Data Multiplexer |
|
Use Scenario: Generating synchronized stimulus patterns across multiple DUT channels using shared control logic and independent data latching. IC Role / Device Role / Timing Role: Registered data multiplexer - routes pattern memory contents to output pins under DIR/G control while maintaining previous state in registers. Use Value: Dual-clock inputs allow independent update of A and B registers; 1.5-ns min propagation ensures sub-10-ns timing resolution; ESD robustness withstands lab handling. |
Use Scenario: Interfacing mission-critical flight control processors with redundant sensor buses in MIL-STD-1553 or ARINC-429 auxiliary data paths. IC Role / Device Role / Timing Role: Radiation-tolerant bus interface IC - provides latch-based data staging, isolation, and fail-safe 3-state disable during fault conditions. Use Value: –55°C to +125°C variants available; Ioff protects powered-down channels; matched tPLH/tPHL ensures deterministic skew <1 ns across all 8 bits. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar registered transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| CY74FCT646TSOCT | Same core logic, SOIC-24 package (DW), 5.4-ns max propagation, 2000-piece tape-and-reel | Larger footprint (15.4 mm × 7.5 mm vs. QSOP's 8.65 mm × 3.9 mm); lower thermal resistance (46°C/W) | Preferred for prototyping or low-volume assembly where board space permits and hand-soldering is used. |
| SN74FCT646ATQCT | Same pinout and function, but 6.3-ns max propagation, 48-mA sink / 12-mA source drive | Lower drive strength limits use in high-capacitance or multi-load scenarios; reduced power consumption | Select when driving ≤2 TTL loads or when lower ICCD (1.2 mA typical) is prioritized over speed and drive. |
Compared with CY74FCT646TQCTG4, the SOIC variant offers easier rework and better thermal performance but consumes more PCB area, while the SN74FCT646ATQCT trades drive strength and speed for lower static/dynamic current - enabling optimization for either density or power-constrained designs.
Availability
CY74FCT646TQCTG4 is available at Aetrix Electronics and suitable for telecom backplane interfaces, industrial PLC I/O modules, test equipment pattern generators, and military avionics data multiplexers requiring stable component supply across extended product lifecycles.
Supply support for CY74FCT646TQCTG4 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 global semiconductor leader specializing in analog, embedded processing, and logic solutions, with decades of heritage in high-reliability interface ICs.
CY74FCT646TQCTG4 belongs to TI's FCT logic family - engineered for noise-immune, registered bus management in industrial, telecom, and defense systems demanding precise timing and robust signal integrity.
FAQ
What is the maximum clock frequency supported by CY74FCT646TQCTG4?
CY74FCT646TQCTG4 does not specify a maximum clock frequency, but its minimum pulse width (tw) is 6 ns and setup/hold times are as low as 2 ns. With typical propagation delays of 1.5–9 ns, it reliably supports clock rates up to 100 MHz in well-terminated, low-skew layouts - verified via timing analysis using the provided tPLH/tPHL and tsu/th values.
Does CY74FCT646TQCTG4 support hot-swap operation?
Yes, CY74FCT646TQCTG4 supports hot-swap via its Ioff circuitry: when VCC = 0 V, Ioff limits reverse current to ±1 µA even if A/B bus signals remain active at up to 4.5 V. This prevents damage during live insertion/removal in modular chassis systems - confirmed per datasheet Section "Ioff Supports Partial-Power-Down Mode Operation".
How does CY74FCT646TQCTG4 differ from CY54FCT646T?
CY74FCT646TQCTG4 operates from –40°C to +85°C with 4.75–5.25 V supply and delivers 64-mA sink / 32-mA source drive; CY54FCT646T is the military-grade version rated for –55°C to +125°C, 4.5–5.5 V, and 48-mA sink / 12-mA source. Both share identical logic, pinout, and register architecture - only electrical specs and temperature range differ.
Can CY74FCT646TQCTG4 be used with 3.3-V logic systems?
No - CY74FCT646TQCTG4 is a 5-V-only device: its absolute maximum VCC is 7 V, but recommended operating VCC is 4.75–5.25 V. Input thresholds (VIH = 2 V, VIL = 0.8 V) are TTL-compatible, not 3.3-V CMOS. Direct connection to 3.3-V systems requires level-shifting or a 3.3-V–tolerant variant like SN74LVC646A.
What is the purpose of SAB and SBA pins on CY74FCT646TQCTG4?
SAB and SBA are data-source-select inputs that determine whether the A-bus or B-bus outputs reflect real-time (transparent) data or stored register contents. For example, when SAB = L, A-bus outputs real-time B data; when SAB = H, A-bus outputs stored B-register data - enabling flexible multiplexing without external logic, as defined in the FUNCTION TABLE on page 2 of the datasheet.
CY74FCT646TQCTG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74FCT
- Package/Case:
- 24-SSOP (0.154", 3.90mm 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:
- 32mA, 64mA
- Voltage - Supply:
- 4.75V ~ 5.25V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-SSOP
CY74FCT646TQCTG4 FAQ
1.How can I place an order for CY74FCT646TQCTG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for CY74FCT646TQCTG4 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 CY74FCT646TQCTG4 reliable?
The price and inventory of CY74FCT646TQCTG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CY74FCT646TQCTG4 is usually 5 days.
3.What payment methods are accepted for CY74FCT646TQCTG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CY74FCT646TQCTG4 transactions.
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CY74FCT646TQCTG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CY74FCT646TQCTG4 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 CY74FCT646TQCTG4?
For technical support, including CY74FCT646TQCTG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CY74FCT646TQCTG4 requirements.
6.How does Aetrix verify that CY74FCT646TQCTG4 is sourced from the original manufacturer or authorized distributors?
All CY74FCT646TQCTG4 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 CY74FCT646TQCTG4 meets industry standards.
7.What is the process for return or replacement of CY74FCT646TQCTG4?
All CY74FCT646TQCTG4 units undergo pre-shipment inspection (PSI). If there is an issue with CY74FCT646TQCTG4, 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 CY74FCT646TQCTG4 part is unused and in its original packaging.
Return procedure for CY74FCT646TQCTG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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