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Texas Instruments CY74FCT646TQCTE4
- Part No.:
- CY74FCT646TQCTE4
- Manufacturer:
- Texas Instruments
- Package:
- 24-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
CY74FCT646TQCTE4.pdf
- Description:
- IC TXRX NON-INVERT 5.25V 24SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,048
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Product details
Overview
CY74FCT646TQCTE4 from Texas Instruments is an 8-bit registered transceiver with 3-state outputs, designed for bidirectional data routing between A and B buses in TTL- and FCT-compatible digital systems. It features independent A/B registers, edge-rate control for noise reduction, Ioff partial-power-down support, 64-mA sink / 32-mA source drive strength, and operates from 4.75 V to 5.25 V across –40°C to +85°C.
For engineers reviewing the CY74FCT646TQCTE4 datasheet, CY74FCT646TQCTE4 pinout, CY74FCT646TQCTE4 application, or CY74FCT646TQCTE4 equivalent, key selection criteria include registered bus isolation capability, dual-clock (CPAB/CPBA) timing control, SAB/SBA multiplexed output sourcing, DIR/G-controlled direction and enable logic, and compatibility with legacy FCT logic families.
Technical Context
This device implements a dual-bus registered transceiver architecture with separate clock inputs (CPAB, CPBA) for latching data into A and B registers independently. Its functional modes-real-time transfer, stored-data transfer, and isolation-are controlled by DIR, G, SAB, and SBA signals per the documented function table.
The IC integrates edge-rate control circuitry to limit slew rate and reduce switching noise, while Ioff circuitry ensures safe operation during partial power-down by disabling outputs and blocking reverse current when VCC = 0 V. Input thresholds (VIH = 2 V, VIL = 0.8 V) and output levels (VOH = 2.4 V min at –32 mA, VOL = 0.55 V max at 64 mA) are fully TTL-compatible.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Bus Width | 8-bit bidirectional data path with independent A and B register storage |
| Supply Voltage | 4.75 V to 5.25 V - ensures stable operation within industrial TTL supply tolerance |
| Output Drive | 64-mA sink / 32-mA source - supports heavy capacitive loads and fanout to multiple TTL inputs |
| Propagation Delay | 1.5 ns (min) to 9 ns (max) - enables high-speed synchronous bus interfacing up to ~100 MHz system clock domains |
| Ioff Support | Active at VCC = 0 V - prevents backflow current during hot-swap or partial-power-down sequencing |
| ESD Rating | 2000-V HBM, 200-V MM, 1000-V CDM - meets JEDEC JESD22-A114/A115/C101 for robust board-level handling |
| Operating Temp | –40°C to +85°C - qualified for commercial and extended industrial ambient environments |
Pinout & Package
Package: QSOP-24 (DBQ), 3.9 mm × 8.7 mm body, 0.635 mm pitch, RoHS-compliant NiPdAu lead finish, MSL Level-2-260°C-1 year.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| G | Output-enable control input | High disables all A/B outputs (3-state); low enables transceiver or register output based on DIR and select controls |
| DIR | Direction control input | Low routes B-bus data to A-bus; high routes A-bus data to B-bus - determines primary data flow path when G is active |
| CPAB | Register A clock input | Low-to-high transition latches real-time or selected data into A register from B bus or internal multiplexer |
| CPBA | Register B clock input | Low-to-high transition latches real-time or selected data into B register from A bus or internal multiplexer |
| SAB | A-bus output source select | Low selects real-time B-bus data; high selects stored B-register data for output onto A bus |
| SBA | B-bus output source select | Low selects real-time A-bus data; high selects stored A-register data for output onto B bus |
| A1–A8 | A-bus I/O terminals | Bi-directional pins serving as inputs to A register and outputs from A register or B register (via DIR/G logic) |
| B1–B8 | B-bus I/O terminals | Bi-directional pins serving as inputs to B register and outputs from B register or A register (via DIR/G logic) |
| VCC | Power supply | 5-V nominal supply rail; decoupling required near pin for noise-sensitive high-speed operation |
| GND | Ground reference | Common return path for all logic and I/O circuits; must be low-impedance for signal integrity |
Key Features
| Feature | Design Value |
|---|---|
| Independent A/B register storage | Enables asynchronous capture and hold of data on each bus without cross-contamination or timing dependency |
| Edge-rate controlled outputs | Reduces simultaneous switching noise (SSN) and EMI in dense PCB layouts with fast edge transitions |
| Ioff partial-power-down protection | Prevents damaging current flow from live bus lines into unpowered device, supporting hot-plug and power-gating designs |
| Matched rise/fall times | Minimizes duty-cycle distortion in clocked data paths and improves timing margin in synchronous systems |
| FCT-family pin/function compatibility | Direct drop-in replacement for legacy CY74FCT646T variants without layout or firmware changes |
Applications
| Backplane Data Routing | Industrial PLC I/O Module |
|---|---|
Use Scenario: High-reliability data exchange between CPU and peripheral cards in modular rack-based systems. IC Role / Device Role / Timing Role: Registered transceiver managing isolated A/B bus segments with clocked handshaking and direction control. Use Value: Prevents bus contention during hot-swap events and enables deterministic latency via register staging before transmission. | Use Scenario: Interfacing microcontroller-based logic controllers with field I/O cards operating at different voltage or timing domains. IC Role / Device Role / Timing Role: Bidirectional level-translation and data buffering with independent register hold for scan-cycle synchronization. Use Value: Eliminates metastability risk during I/O scanning by capturing sensor/actuator data into registers before CPU read/write cycles. |
| Legacy System Bus Extension | TTL-Compatible Memory Interface |
Use Scenario: Extending aging 8-bit data buses in test equipment or instrumentation where new logic must coexist with vintage FCT components. IC Role / Device Role / Timing Role: Pin- and function-compatible transceiver preserving original timing margins and drive requirements. Use Value: Maintains signal integrity and setup/hold compliance without redesigning PCB traces or adjusting clock skew. | Use Scenario: Connecting microcontrollers to parallel SRAM or EPROM devices requiring registered address/data staging. IC Role / Device Role / Timing Role: Registered data path controller synchronizing memory access with CPU clock domain and enabling burst-mode transfers. Use Value: Enables reliable 8-bit memory reads/writes at >20 MHz by eliminating combinatorial path delays through register staging. |
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), 2000-piece tape-and-reel, 5.4 ns max propagation delay | Larger footprint and lower thermal resistance than QSOP; better suited for manual assembly or low-volume prototyping | Select when board space permits larger SOIC and thermal management is prioritized over density |
| CY74FCT646ATQCT | Same QSOP-24 package but faster 6.3 ns max propagation delay; reduced drive (48-mA sink / 12-mA source) | Lower power consumption and tighter timing margins; insufficient for high-fanout or heavy-load applications | Select only if system timing budget allows tighter delays and load drive requirements are ≤48 mA sink |
Compared with CY74FCT646TQCTE4, CY74FCT646TSOCT offers identical functionality in a more thermally robust SOIC package but occupies 2.5× more PCB area, while CY74FCT646ATQCT trades drive strength for speed - making CY74FCT646TQCTE4 optimal for high-reliability, high-drive registered bus interfaces where density and noise control are critical.
Availability
CY74FCT646TQCTE4 is available at Aetrix Electronics and suitable for industrial PLC I/O modules, legacy bus extension systems, backplane data routing, and TTL-compatible memory interfaces requiring stable component supply and long-term lifecycle continuity.
Supply support for CY74FCT646TQCTE4 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 for industrial, automotive, and communications markets.
The CY74FCT646TQCTE4 belongs to TI's FCT logic family, engineered for high-speed, low-noise, TTL-compatible digital interfacing in mission-critical industrial and instrumentation systems.
FAQ
What is the maximum clock frequency supported by CY74FCT646TQCTE4?
CY74FCT646TQCTE4 does not specify a maximum clock frequency in its datasheet; instead, it defines minimum pulse width (tw ≥ 6 ns) and setup/hold times (tsu ≥ 4 ns, th ≥ 2 ns). Based on these, the practical maximum clock rate for reliable register operation is approximately 83 MHz (1/12 ns cycle), assuming clean edges and proper load conditions. The device is optimized for synchronous bus applications rather than continuous high-frequency clocking.
Does CY74FCT646TQCTE4 support hot-swap operation?
Yes, CY74FCT646TQCTE4 supports hot-swap operation via its Ioff circuitry, which disables outputs and blocks reverse current when VCC = 0 V. This allows safe insertion/removal while other system rails remain powered, provided external series resistors or current-limiting design practices are applied to prevent transient overstress on live bus lines during plug-in.
Can CY74FCT646TQCTE4 operate with a 3.3-V supply?
No, CY74FCT646TQCTE4 is specified only for 4.75 V to 5.25 V operation per its recommended operating conditions. Applying 3.3 V violates the minimum VCC requirement and will result in undefined logic behavior, insufficient output drive, and potential failure to meet VIH/VIL thresholds. For 3.3-V systems, consider TI's LVC or ALVC logic families instead.
How does the SAB/SBA control logic affect output sourcing in CY74FCT646TQCTE4?
In CY74FCT646TQCTE4, SAB selects the source for A-bus outputs: low = real-time B-bus data, high = stored B-register data. SBA selects the source for B-bus outputs: low = real-time A-bus data, high = stored A-register data. These controls operate independently of DIR and G, enabling flexible multiplexed data routing without altering direction or enable state.
Is CY74FCT646TQCTE4 pin-compatible with CY54FCT646T devices?
No, CY74FCT646TQCTE4 (QSOP-24) is not pin-compatible with CY54FCT646T variants, which use D-package (CDIP-24) or L-package (LCCC-28) footprints. While functionally identical and electrically compatible, mechanical incompatibility requires PCB redesign. Pin mapping differs across packages - e.g., CY54FCT646T places CPAB/CPBA on pins 1/23, whereas CY74FCT646TQCTE4 places them on pins 1/23 in QSOP but with distinct pin 1 orientation and thermal pad absence.
CY74FCT646TQCTE4 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
CY74FCT646TQCTE4 FAQ
1.How can I place an order for CY74FCT646TQCTE4 through Aetrix?
Please submit a Request for Quotation (RFQ) for CY74FCT646TQCTE4 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 CY74FCT646TQCTE4 reliable?
The price and inventory of CY74FCT646TQCTE4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CY74FCT646TQCTE4 is usually 5 days.
3.What payment methods are accepted for CY74FCT646TQCTE4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CY74FCT646TQCTE4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CY74FCT646TQCTE4?
CY74FCT646TQCTE4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CY74FCT646TQCTE4 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 CY74FCT646TQCTE4?
For technical support, including CY74FCT646TQCTE4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CY74FCT646TQCTE4 requirements.
6.How does Aetrix verify that CY74FCT646TQCTE4 is sourced from the original manufacturer or authorized distributors?
All CY74FCT646TQCTE4 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 CY74FCT646TQCTE4 meets industry standards.
7.What is the process for return or replacement of CY74FCT646TQCTE4?
All CY74FCT646TQCTE4 units undergo pre-shipment inspection (PSI). If there is an issue with CY74FCT646TQCTE4, 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 CY74FCT646TQCTE4 part is unused and in its original packaging.
Return procedure for CY74FCT646TQCTE4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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