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Texas Instruments CY74FCT646TSOCT
- Part No.:
- CY74FCT646TSOCT
- Manufacturer:
- Texas Instruments
- Package:
- 24-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
CY74FCT646TSOCT.pdf
- Description:
- IC TXRX NON-INVERT 5.25V 24SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,800
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Product details
Overview
CY74FCT646TSOCT from Texas Instruments is an 8-bit registered transceiver with 3-state outputs, designed for bidirectional data bus isolation and registered multiplexing in TTL- and FCT-compatible 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). Key confirmed specs: 64-mA sink / 32-mA source drive, 5.4-ns max propagation delay (tPLH/tPHL), 1.5-ns min pulse width, and Ioff support for partial-power-down operation.
For engineers reviewing the CY74FCT646TSOCT datasheet, CY74FCT646TSOCT pinout, CY74FCT646TSOCT application, or CY74FCT646TSOCT equivalent, this page delivers verified functional architecture, real-time vs. registered mode behavior, noise-suppressed edge-rate control, TTL-level compatibility, and SOIC-24 package–specific thermal and drive characteristics - all critical for bus arbitration, memory interface buffering, and legacy system upgrades.
Technical Context
The CY74FCT646TSOCT implements a dual-bus registered transceiver architecture with separate D-type flip-flops per data line, enabling simultaneous storage of A- and B-bus data on rising edges of CPAB and CPBA. Its control logic supports four operational modes: isolation (G high), real-time transfer (G low + DIR), stored-data transfer (G low + SAB/SBA), and mixed-mode multiplexing.
It integrates edge-rate control circuitry to reduce switching noise, matched rise/fall times (typical 3.3 V VOH), and Ioff protection that disables outputs when VCC = 0 V - preventing backflow current during partial power-down. Input thresholds (VIH = 2 V, VIL = 0.8 V) and output drive (64 mA sink) are fully specified across –40°C to 85°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Function | 8-bit registered bidirectional transceiver with independent A/B registers and 3-state outputs |
| Supply Voltage | VCC = 4.75 V to 5.25 V - ensures stable TTL-compatible operation without overvoltage stress |
| Output Drive | 64 mA sink / 32 mA source - supports heavy capacitive loads and fanout to multiple TTL inputs |
| Propagation Delay | tPLH/tPHL ≤ 5.4 ns (max) - enables reliable timing in 100+ MHz bus systems with setup/hold margins |
| Ioff Support | ±1 µA leakage at VCC = 0 V - allows safe hot-insertion and partial power-down in multi-rail systems |
| ESD Protection | 2000-V HBM, 200-V MM, 1000-V CDM - meets industrial-grade robustness requirements |
| Package | SOIC-24 (DW), 10.75 mm × 15.7 mm footprint - compatible with standard PCB assembly and reflow profiles |
Pinout & Package
Package: SOIC-24 (DW), RoHS-compliant, moisture sensitivity level 1 (260°C peak reflow), 2000-piece tape-and-reel format.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 4–11, 14–20, 22, 23 | 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 |
| 3, 21 | DIR, G | Direction control (DIR) selects bus flow direction; Output-enable (G) disables all outputs when high |
| 12 | GND | Ground reference for logic and power return path |
| 13 | VCC | 5-V supply input - must be decoupled locally to suppress switching noise |
| 24 | NC | No internal connection - left unconnected per TI specification |
| 17, 18 | CPAB, CPBA | Independent clock inputs: CPAB clocks data into register A; CPBA clocks data into register B |
| 19, 20 | SAB, SBA | Data-source select: SAB controls whether A-bus output comes from real-time or stored B data; SBA does same for B-bus |
Key Features
| Feature | Design Value |
|---|---|
| Edge-rate controlled outputs | Reduces simultaneous switching noise (SSN) by limiting dv/dt - critical for signal integrity in dense PCB layouts |
| Independent A/B register storage | Enables asynchronous capture and forwarding of data from either bus without cross-contamination or timing dependency |
| Ioff partial-power-down protection | Prevents damaging reverse current flow when VCC is off but buses remain active - essential for hot-swap and modular backplane designs |
| TTL-compatible input/output levels | VIH = 2 V / VIL = 0.8 V inputs and VOH ≥ 2.4 V / VOL ≤ 0.55 V outputs ensure seamless integration with legacy 5-V logic families |
| Matched rise/fall times | Minimizes duty-cycle distortion in clocked data paths - preserves timing margins in synchronous bus applications |
Applications
| Industrial PLC Backplane Interface | Legacy Memory Bus Buffering |
|---|---|
Use Scenario: Isolating CPU address/data bus from modular I/O expansion slots in programmable logic controllers. IC Role / Device Role / Timing Role: Registered transceiver managing time-critical read/write handshaking between processor and peripheral modules via shared parallel bus. Use Value: Ioff support prevents backfeed during hot-swap of I/O cards; 64-mA drive ensures signal integrity across 20 cm backplane traces. |
Use Scenario: Interfacing modern microcontrollers to legacy SRAM or EPROM chips requiring registered address latching and bidirectional data flow. IC Role / Device Role / Timing Role: Dual-register buffer capturing address on CPAB and data on CPBA, then synchronously presenting to memory with DIR/G-controlled direction. Use Value: 5.4-ns propagation delay and 1.5-ns pulse width meet tight access timing of 15-ns SRAMs; TTL compatibility eliminates level-shifter components. |
| Test Equipment Digital Pattern Generator | Automotive ECU Diagnostic Interface |
Use Scenario: Generating precise, glitch-free stimulus patterns for digital IC validation using programmable pattern memory and real-time bus monitoring. IC Role / Device Role / Timing Role: Multiplexing between stored test vectors (from internal registers) and live bus traffic (transparent mode) under SAB/SBA control. Use Value: Edge-rate control minimizes crosstalk in high-density test head wiring; 3-state outputs enable shared bus contention management. |
Use Scenario: Bridging microcontroller UART or CAN controller to legacy diagnostic connectors (e.g., ISO 9141-2 K-line) requiring 5-V tolerant, noise-immune bidirectional signaling. IC Role / Device Role / Timing Role: Level-translating and isolating diagnostic data path while supporting fast response to external bus requests via DIR/G-controlled enable timing. Use Value: 2000-V HBM ESD rating withstands automotive ESD events; Ioff protects MCU during battery disconnect scenarios. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar registered transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74FCT646ATSOCT | Same SOIC-24 package, identical pinout, but rated for –40°C to 85°C with 6.3-ns max tPLH/tPHL (slower than CY74FCT646TSOCT's 5.4 ns) | Lower-speed variant suitable where timing margin exceeds 0.9 ns; otherwise requires layout verification for setup/hold compliance | Select when cost sensitivity outweighs 0.9-ns timing advantage and full 5.4-ns performance is not required. |
| 74ACT646SCX | ACT-family device in SOIC-24; higher VOH (≥3.7 V), lower IOL (24 mA), no Ioff support, and 7.5-ns max propagation delay | Lacks partial-power-down capability and has reduced drive strength - unsuitable for hot-swap or high-fanout legacy bus loading | Choose only for non-power-sensitive designs where ACT logic family compatibility is mandatory and drive requirements are ≤24 mA. |
Compared with SN74FCT646ATSOCT and 74ACT646SCX, CY74FCT646TSOCT delivers the fastest propagation (5.4 ns), highest sink current (64 mA), and unique Ioff protection - making it the optimal choice for timing-critical, hot-pluggable, or high-noise industrial bus interfaces where reliability and signal fidelity are non-negotiable.
Availability
CY74FCT646TSOCT is available at Aetrix Electronics and suitable for industrial PLC backplanes, legacy memory interfacing, automated test equipment, automotive diagnostic gateways, and embedded system bus arbitration requiring stable component supply and long-term lifecycle support.
Supply support for CY74FCT646TSOCT 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 industrial and automotive IC design.
CY74FCT646TSOCT belongs to TI's FCT logic family - engineered for noise-immune, TTL-compatible 5-V bus interfacing with enhanced drive, registered data control, and partial-power-down safety in mission-critical systems.
FAQ
What is the maximum operating frequency supported by CY74FCT646TSOCT?
CY74FCT646TSOCT does not specify a maximum clock frequency directly, but its 5.4-ns maximum propagation delay (tPLH/tPHL) and 1.5-ns minimum pulse width (tw) support reliable operation in systems with clock periods ≥10.8 ns - corresponding to a practical upper limit of approximately 92 MHz for registered data transfers. Real-time transparent mode performance depends on external bus timing constraints.
Does CY74FCT646TSOCT support hot-swap or partial-power-down operation?
Yes, CY74FCT646TSOCT includes Ioff circuitry that actively disables outputs when VCC = 0 V, limiting leakage current to ±1 µA. This feature enables safe hot-insertion into live backplanes and partial-power-down operation in multi-rail systems - a key differentiator versus non-Ioff logic families like 74ACT or standard 74LS.
What is the difference between CY74FCT646TSOCT and CY74FCT646ATSOCT?
CY74FCT646TSOCT offers 5.4-ns maximum propagation delay and 64-mA sink drive, while CY74FCT646ATSOCT has 6.3-ns max delay and identical drive. Both share SOIC-24 packaging, –40°C to 85°C temperature range, and full pin compatibility. The "T" suffix denotes the faster speed grade optimized for timing-critical applications.
Can CY74FCT646TSOCT interface directly with 3.3-V logic devices?
No - CY74FCT646TSOCT is a 5-V-only device with TTL-compatible input thresholds (VIH = 2 V, VIL = 0.8 V) and 5-V supply requirement (VCC = 4.75–5.25 V). Direct connection to 3.3-V logic risks overvoltage damage to downstream receivers. A level-shifting solution (e.g., TXB0108 or discrete resistor divider with clamping) is required for mixed-voltage interfacing.
Is there a lead-free and RoHS-compliant version of CY74FCT646TSOCT?
Yes, CY74FCT646TSOCT is RoHS-compliant with NiPdAu (NIPDAU) lead finish, MSL Level-1 rating (unlimited floor life), and qualified for standard 260°C reflow. The part marking "FCT646" appears on the top surface, and full compliance documentation is available via Texas Instruments' official product page and material declarations.
CY74FCT646TSOCT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74FCT
- Package/Case:
- 24-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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-SOIC
CY74FCT646TSOCT FAQ
1.How can I place an order for CY74FCT646TSOCT through Aetrix?
Please submit a Request for Quotation (RFQ) for CY74FCT646TSOCT 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 CY74FCT646TSOCT reliable?
The price and inventory of CY74FCT646TSOCT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CY74FCT646TSOCT is usually 5 days.
3.What payment methods are accepted for CY74FCT646TSOCT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CY74FCT646TSOCT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CY74FCT646TSOCT?
CY74FCT646TSOCT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CY74FCT646TSOCT 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 CY74FCT646TSOCT?
For technical support, including CY74FCT646TSOCT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CY74FCT646TSOCT requirements.
6.How does Aetrix verify that CY74FCT646TSOCT is sourced from the original manufacturer or authorized distributors?
All CY74FCT646TSOCT 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 CY74FCT646TSOCT meets industry standards.
7.What is the process for return or replacement of CY74FCT646TSOCT?
All CY74FCT646TSOCT units undergo pre-shipment inspection (PSI). If there is an issue with CY74FCT646TSOCT, 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 CY74FCT646TSOCT part is unused and in its original packaging.
Return procedure for CY74FCT646TSOCT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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