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Texas Instruments CY74FCT646ATSOCTE4
- Part No.:
- CY74FCT646ATSOCTE4
- Manufacturer:
- Texas Instruments
- Package:
- 24-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
CY74FCT646ATSOCTE4.pdf
- Description:
- IC TXRX NON-INVERT 5.25V 24SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,194
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Product details
Overview
CY74FCT646ATSOCTE4 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 systems. It features independent A/B registers, dual clock inputs (CPAB/CPBA), direction control (DIR), output-enable (G), and multiplexed real-time/stored data selection (SAB/SBA). It delivers 64-mA sink / 32-mA source drive at 5-V operation and supports partial-power-down via Ioff.
For engineers reviewing the CY74FCT646ATSOCTE4 datasheet, CY74FCT646ATSOCTE4 pinout, CY74FCT646ATSOCTE4 application, or CY74FCT646ATSOCTE4 equivalent, this device is selected for high-noise-margin bus interfacing in industrial control backplanes, legacy system upgrades requiring FCT timing compatibility, and applications needing register-controlled data staging with 3-state isolation.
Technical Context
The CY74FCT646ATSOCTE4 implements dual 8-bit D-type flip-flop registers synchronized to low-to-high transitions on CPAB (A→B) and CPBA (B→A), enabling independent latching of data from either bus. Its transceiver logic supports four operational modes-real-time transfer, stored-data transfer, isolation, and simultaneous A/B register storage-controlled by DIR, G, SAB, and SBA.
Edge-rate control circuitry ensures matched rise/fall times and reduced switching noise, while Ioff protection disables outputs during power-down to prevent backflow current. The device maintains full TTL input/output voltage compatibility (VIH = 2 V, VIL = 0.8 V) and operates across –40°C to +85°C with 4.75–5.25 V supply.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | FCT (Fast CMOS TTL-compatible), 5-V only |
| Bus Width | 8-bit bidirectional with independent A and B registers |
| Max Propagation Delay | 6.3 ns (A↔B path, tPLH/tPHL, TA = 85°C) |
| Output Drive | 64 mA sink / 32 mA source per pin (guaranteed at VCC = 4.75 V) |
| Ioff Support | Enables safe partial-power-down; leakage ≤ ±1 µA when VCC = 0 V |
| ESD Rating | 2000-V HBM, 200-V MM, 1000-V CDM per JESD22 |
| Operating Temperature | –40°C to +85°C (industrial grade) |
Pinout & Package
Package: SOIC-24 (DW), 7.5 mm × 15.4 mm body, gull-wing leads, RoHS-compliant NiPdAu finish, MSL Level-1 (unlimited reflow).
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | A1–A8 | A-bus data inputs (register A) / outputs (register B); bidirectional I/O with 3-state control |
| 9, 10, 11, 13, 14, 15, 16, 17 | B1–B8 | B-bus data inputs (register B) / outputs (register A); bidirectional I/O with 3-state control |
| 12 | GND | Ground reference for all logic and power domains |
| 24 | VCC | 5-V supply input (4.75–5.25 V); decoupling required per pin |
| 18 | G | Global 3-state enable: high = outputs high-Z; low = outputs active |
| 19 | DIR | Direction control: low = B→A transfer; high = A→B transfer |
| 20 | CPAB | Low-to-high clock edge latches A-bus data into register B |
| 21 | CPBA | Low-to-high clock edge latches B-bus data into register A |
| 22 | SAB | Selects A-bus output source: low = real-time A data; high = stored B data |
| 23 | SBA | Selects B-bus output source: low = real-time B data; high = stored A data |
Key Features
| Feature | Design Value |
|---|---|
| Independent A/B register staging | Enables concurrent capture of data from both buses without contention, critical for handshake-free bus arbitration |
| Edge-rate controlled outputs | Reduces simultaneous switching noise (SSN) by limiting di/dt; eliminates need for external series termination in most PCB layouts |
| Ioff partial-power-down | Prevents reverse current flow when VCC = 0 V, allowing hot-swap or mixed-voltage domain operation without latch-up risk |
| FCT/F logic pinout & drive compatibility | Direct drop-in replacement for CY74FCT646T and SN74FCT646 in existing designs; no PCB change required |
| Matched rise/fall times | Ensures minimal skew between logic edges, preserving setup/hold margins in high-speed synchronous bus transfers |
Applications
| Industrial Backplane Interface | Legacy System Bus Extension |
|---|---|
|
Use Scenario: Interfacing a modern microcontroller unit (MCU) to a legacy 8-bit ISA-style backplane with separate address/data strobes and timing-critical handshaking. IC Role / Device Role / Timing Role: Registered transceiver buffering and synchronizing data between the MCU's fast GPIO and the slower, noise-prone backplane; registers absorb timing skews and provide clean setup/hold windows. Use Value: Eliminates external glue logic and timing margin violations; enables reliable 6.3-ns propagation-limited transfers at 5-V TTL levels without signal integrity degradation. |
Use Scenario: Upgrading a 1990s programmable logic controller (PLC) CPU board where original CY74FCT646T parts are obsolete but board layout must remain unchanged. IC Role / Device Role / Timing Role: Pin- and function-compatible replacement providing identical register control, 3-state behavior, and FCT timing specs (tsu = 2 ns, th = 1.5 ns). Use Value: Zero-layout-change migration path; same SOIC-24 footprint, same drive strength, same thermal profile (θJA = 46°C/W), and full industrial temperature support. |
| Isolated Data Acquisition Subsystem | Multi-Source Sensor Aggregation |
|
Use Scenario: Isolating a noisy analog sensor acquisition module from a digital processing subsystem using optocouplers, where the CY74FCT646ATSOCTE4 buffers and registers sensor data before isolation. IC Role / Device Role / Timing Role: Holding sampled sensor values in internal registers during opto-isolator latency; G and DIR pins coordinate gated data release synchronized to downstream clock. Use Value: Prevents metastability and data loss during isolation delays; Ioff allows safe power sequencing (sensor side powered down first) without backfeed. |
Use Scenario: Aggregating parallel 8-bit outputs from three different sensor ICs (e.g., ADCs, encoders) onto a shared microcontroller data bus with time-multiplexed access. IC Role / Device Role / Timing Role: Staging each sensor's output in dedicated A/B registers; SAB/SBA selects which sensor's stored data appears on the bus under software control. Use Value: Enables deterministic, non-overlapping sensor readout without bus contention; eliminates need for external multiplexer ICs or complex FPGA logic. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar registered transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| CY74FCT646TSOCT | Slower speed grade: 9 ns max propagation delay vs. 6.3 ns; identical pinout, package, and register architecture | Acceptable in lower-frequency systems (<15 MHz bus clock) where timing margin is relaxed; not suitable for 6.3-ns-critical paths | Select CY74FCT646TSOCT only if design timing analysis confirms slack ≥ 2.7 ns; otherwise CY74FCT646ATSOCTE4 is required. |
| SN74FCT646ATPC | Same speed (6.3 ns), same 8-bit registered transceiver function, but PDIP-24 package (not SOIC); identical electrical specs and pin mapping | Used in through-hole prototyping or legacy repair where SOIC rework is impractical; incompatible with automated SMT assembly | Choose SN74FCT646ATPC only for hand-soldered evaluation or field repair; CY74FCT646ATSOCTE4 is preferred for volume production and thermal performance (lower θJA). |
Compared with CY74FCT646TSOCT and SN74FCT646ATPC, the CY74FCT646ATSOCTE4 uniquely combines 6.3-ns timing, SOIC-24 surface-mount packaging, and industrial temperature range - making it the sole option for space-constrained, high-reliability, high-speed bus interface applications requiring drop-in FCT compatibility.
Availability
CY74FCT646ATSOCTE4 is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy system upgrades, and isolated data acquisition subsystems requiring stable component supply, long-term lifecycle support, and guaranteed RoHS compliance.
Supply support for CY74FCT646ATSOCTE4 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 over 50 years of innovation in high-reliability interface ICs.
The CY74FCT646ATSOCTE4 belongs to TI's FCT logic family, engineered for noise-immune, TTL-compatible bus interfacing in industrial, telecom, and computing infrastructure where timing precision, drive strength, and power-down safety are critical.
FAQ
What is the maximum operating frequency supported by the CY74FCT646ATSOCTE4?
The CY74FCT646ATSOCTE4 does not specify a maximum clock frequency in its datasheet; instead, it guarantees timing parameters such as 6.3 ns max propagation delay (tPLH/tPHL) and 2 ns min setup time (tsu) at 5.25 V and 85°C. System-level frequency depends on bus loading and layout, but designs commonly achieve reliable operation up to 80 MHz with proper termination and 50-pF load.
Does the CY74FCT646ATSOCTE4 support mixed-voltage operation (e.g., 3.3-V inputs with 5-V VCC)?
No. The CY74FCT646ATSOCTE4 is a 5-V-only device with TTL-compatible input thresholds (VIH = 2.0 V min, VIL = 0.8 V max) and requires VCC between 4.75 V and 5.25 V. It does not support 3.3-V logic inputs directly; level-shifting circuitry is required for interfacing with 3.3-V systems.
How does the Ioff feature function in the CY74FCT646ATSOCTE4 during power-down sequences?
When VCC = 0 V, the Ioff circuitry in the CY74FCT646ATSOCTE4 disables all outputs, limiting leakage current to ±1 µA even if signals are present on A or B bus pins. This prevents damaging backflow current into the unpowered device, enabling safe hot-swap and partial-power-down in multi-rail systems.
Can the CY74FCT646ATSOCTE4 operate in transparent (non-registered) mode?
Yes. When CPAB and CPBA are held static (not clocked), and G is low, the CY74FCT646ATSOCTE4 passes data directly between A and B buses in real-time - subject to DIR and SAB/SBA control. However, registered latching only occurs on low-to-high clock transitions; no internal bypass path exists outside the defined functional modes.
What is the thermal resistance (θJA) of the CY74FCT646ATSOCTE4 in its SOIC-24 package?
The CY74FCT646ATSOCTE4 in SOIC-24 (DW) package has a specified junction-to-ambient thermal resistance (θJA) of 46°C/W under standard JEDEC test conditions (1-layer board, 1 in² copper pad). Actual thermal performance improves with enhanced PCB copper area and airflow.
CY74FCT646ATSOCTE4 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:
- Discontinued at Digi-Key
- 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
CY74FCT646ATSOCTE4 FAQ
1.How can I place an order for CY74FCT646ATSOCTE4 through Aetrix?
Please submit a Request for Quotation (RFQ) for CY74FCT646ATSOCTE4 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 CY74FCT646ATSOCTE4 reliable?
The price and inventory of CY74FCT646ATSOCTE4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CY74FCT646ATSOCTE4 is usually 5 days.
3.What payment methods are accepted for CY74FCT646ATSOCTE4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CY74FCT646ATSOCTE4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CY74FCT646ATSOCTE4?
CY74FCT646ATSOCTE4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CY74FCT646ATSOCTE4 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 CY74FCT646ATSOCTE4?
For technical support, including CY74FCT646ATSOCTE4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CY74FCT646ATSOCTE4 requirements.
6.How does Aetrix verify that CY74FCT646ATSOCTE4 is sourced from the original manufacturer or authorized distributors?
All CY74FCT646ATSOCTE4 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 CY74FCT646ATSOCTE4 meets industry standards.
7.What is the process for return or replacement of CY74FCT646ATSOCTE4?
All CY74FCT646ATSOCTE4 units undergo pre-shipment inspection (PSI). If there is an issue with CY74FCT646ATSOCTE4, 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 CY74FCT646ATSOCTE4 part is unused and in its original packaging.
Return procedure for CY74FCT646ATSOCTE4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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