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Texas Instruments CY74FCT646ATQCT
- Part No.:
- CY74FCT646ATQCT
- Manufacturer:
- Texas Instruments
- Package:
- 24-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
CY74FCT646ATQCT.pdf
- Description:
- IC TXRX NON-INVERT 5.25V 24SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:170
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Product details
Overview
CY74FCT646ATQCT 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-speed TTL/CMOS mixed-signal systems. It features independent A/B registers, edge-rate controlled outputs (6.3 ns max propagation delay), ±64 mA sink/source drive strength, and Ioff partial-power-down support. It operates across –40°C to +85°C and is used in bus isolation, data multiplexing, and register-controlled interface bridging in industrial control backplanes.
For engineers reviewing the CY74FCT646ATQCT datasheet, CY74FCT646ATQCT pinout, CY74FCT646ATQCT application, or CY74FCT646ATQCT equivalent, key selection criteria include its 6.3 ns speed grade, QSOP-24 package with 0.64 mm pitch, dual-clock (CPAB/CPBA) and dual-select (SAB/SBA) control architecture, and compatibility with 5 V TTL logic levels while supporting partial power-down.
Technical Context
This device implements a dual-bus registered transceiver with separate D-type flip-flop registers for A and B data paths, enabling synchronous storage and selective forwarding of real-time or registered data. Control logic includes DIR (direction), G (output enable), and SAB/SBA (source select), allowing four distinct operational modes: isolation, real-time transfer, stored-data transfer, and simultaneous A↔B register loading.
It integrates edge-rate control circuitry to reduce switching noise, matched rise/fall times (tPLH ≈ tPHL), and Ioff protection that disables outputs when VCC = 0 V-preventing backflow current during partial power-down. Input thresholds comply fully with TTL logic levels (VIH = 2 V min, VIL = 0.8 V max), and output drive meets 5 V CMOS voltage swing (VOH = 3.3 V typ at IOH = –32 mA).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | FCT advanced CMOS - compatible with TTL input/output levels and FCT/F logic pinouts |
| Propagation Delay (max) | 6.3 ns - enables ≤159 MHz bus clocking in registered mode with setup/hold margin |
| Output Drive Strength | 64 mA sink / 32 mA source - supports heavy capacitive loads and fanout to multiple TTL inputs |
| Supply Voltage Range | 4.75 V to 5.25 V - tight 5 V tolerance ensures stable operation under noisy rail conditions |
| Ioff Support | Active at VCC = 0 V - prevents damaging back-current during hot-insertion or partial system power-down |
| Operating Temperature | –40°C to +85°C - qualified for industrial-grade embedded control and instrumentation applications |
| ESD Protection | 2000-V HBM, 200-V MM, 1000-V CDM - exceeds JEDEC JESD22 standards for board-level robustness |
Pinout & Package
CY74FCT646ATQCT is housed in a 24-pin QSOP (DBQ) package with 0.64 mm lead pitch, 8.65 mm × 3.9 mm body size, and moisture sensitivity level (MSL) 2–260°C–1 year. Pin 1 is located in quadrant Q1 per tape-and-reel orientation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A1–A8 | Data register A inputs / B register outputs | 8-bit bidirectional port: driven by A register when DIR = H and G = L; receives data into A register on CPAB↑ |
| B1–B8 | Data register B inputs / A register outputs | 8-bit bidirectional port: driven by B register when DIR = L and G = L; receives data into B register on CPBA↑ |
| CPAB | Low-to-high clock pulse for A register | Loads A-bus data into A register on rising edge; enables synchronous capture from A or B bus |
| CPBA | Low-to-high clock pulse for B register | Loads B-bus data into B register on rising edge; independent timing allows staggered register updates |
| DIR | Direction control input | When G = L: DIR = H routes A→B; DIR = L routes B→A; controls which bus drives outputs |
| G | Output-enable active-low | G = H forces all outputs to high-impedance - enables bus sharing and isolation without disabling registers |
| SAB | Select A data for B-bus output | When DIR = H and G = L: SAB = H selects stored A data; SAB = L selects real-time A data |
| SBA | Select B data for A-bus output | When DIR = L and G = L: SBA = H selects stored B data; SBA = L selects real-time B data |
| VCC | Positive supply | 5 V nominal supply; must be stabilized within 4.75–5.25 V for guaranteed timing and drive performance |
| GND | Ground reference | Common return path for all I/O and internal logic; requires low-inductance connection to minimize ground bounce |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent registers | Enables concurrent capture of A- and B-bus data on separate clock edges - critical for handshake-free inter-bus synchronization |
| Edge-rate controlled outputs | Reduces EMI and ground bounce by limiting dV/dt - improves signal integrity in dense PCB layouts with >50 pF trace capacitance |
| Ioff partial-power-down | Prevents reverse current flow when VCC = 0 V - essential for hot-swap backplane designs and modular system upgrades |
| Matched tPLH/tPHL | Ensures symmetrical rise/fall propagation - eliminates duty-cycle distortion in clock-forwarding or data-retiming applications |
| TTL-compatible input thresholds | Accepts standard 0.8 V/2.0 V TTL logic levels - eliminates need for level-shifting when interfacing legacy controllers or peripherals |
Applications
| Industrial Backplane Interface | Programmable Logic Controller (PLC) I/O Module |
|---|---|
Use Scenario: Isolating CPU address/data bus from field I/O expansion slots while enabling register-controlled data staging. IC Role / Device Role / Timing Role: Registered transceiver managing synchronous handshaking between microcontroller and isolated I/O banks via CPAB/CPBA clocks. Use Value: Eliminates external latch logic; 6.3 ns delay ensures timing closure in 16 MHz bus cycles with 2 ns setup margin. |
Use Scenario: Buffering sensor input data and actuator command signals between FPGA-based control logic and analog/digital I/O stages. IC Role / Device Role / Timing Role: Bidirectional bus interface with independent A/B registers storing sensor readings and actuator states for deterministic scan-cycle execution. Use Value: Ioff support allows safe hot-swap of I/O modules without powering down main controller; 64 mA drive handles 10+ TTL loads per line. |
| Test Equipment Data Acquisition | Automated Test System (ATE) Fixture |
Use Scenario: Multiplexing high-speed digital stimulus/response paths between pattern generator and DUT during boundary-scan or functional test. IC Role / Device Role / Timing Role: Real-time or registered data routing controlled by SAB/SBA select lines - enables dynamic reconfiguration of test signal paths. Use Value: Edge-rate control minimizes crosstalk in multi-channel parallel test setups; 3-state outputs prevent bus contention during test vector transitions. |
Use Scenario: Interfacing programmable test controller with DUT-specific interface boards requiring precise timing alignment and bus isolation. IC Role / Device Role / Timing Role: Clock-synchronized data bridge between controller's local bus and fixture's DUT-side bus, using DIR/G for direction arbitration. Use Value: Matched tPLH/tPHL preserves signal duty cycle integrity across 10+ channels; 2000-V HBM ESD rating withstands handling in production test environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar registered transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| CY74FCT646TQCT | Slower 9 ns propagation delay; identical pinout, drive strength, and feature set | Suitable for cost-sensitive designs where timing margin exceeds 9 ns; lower power at same frequency due to reduced switching activity | Select when system clock rate ≤110 MHz and layout noise immunity is prioritized over speed |
| CY74FCT646CTQCT | Faster 5.4 ns propagation delay; same package and logic function but higher ICCD (dynamic current) | Required for high-speed bus interfaces demanding <6 ns latency; increased supply current necessitates tighter thermal design | Choose when operating at ≥185 MHz bus rates and full timing margin is mandatory |
Compared with CY74FCT646ATQCT, the TQCT variant trades speed for robustness in electrically noisy environments, while the CTQCT variant delivers maximum throughput at the expense of higher dynamic power and stricter layout constraints.
Availability
CY74FCT646ATQCT is available at Aetrix Electronics and suitable for industrial backplane interfaces, PLC I/O modules, automated test equipment, and data acquisition systems requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for CY74FCT646ATQCT 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.
CY74FCT646ATQCT belongs to TI's FCT logic family, engineered for high-speed, low-noise, mixed-voltage system interfacing with emphasis on bus integrity, power-down safety, and TTL/CMOS interoperability.
FAQ
What is the maximum clock frequency supported by CY74FCT646ATQCT in registered mode?
CY74FCT646ATQCT supports a minimum clock pulse width (tw) of 5 ns and setup/hold times of 2 ns/1.5 ns, enabling reliable operation up to 159 MHz in synchronous register-load mode. Actual maximum frequency depends on PCB trace length, load capacitance, and supply stability - verified timing assumes CL = 50 pF and VCC = 5 V.
Does CY74FCT646ATQCT support hot-swap or partial-power-down operation?
Yes, CY74FCT646ATQCT includes Ioff circuitry that disables all outputs when VCC = 0 V, preventing damaging back-current flow during hot-insertion or partial system power-down. This feature is specified across –40°C to +85°C and is validated per JEDEC JESD78.
Can CY74FCT646ATQCT interface directly with 3.3 V logic devices?
No - CY74FCT646ATQCT is a 5 V-only device with TTL-compatible input thresholds (VIH = 2 V min) and 5 V output swing (VOH = 3.3 V typ). Direct connection to 3.3 V logic requires level translation; it is not 3.3 V tolerant and may damage downstream 3.3 V inputs if driven high.
What is the meaning of SAB and SBA pins on CY74FCT646ATQCT?
SAB (Select A for B) and SBA (Select B for A) are data-source select inputs that determine whether real-time or registered data appears on the output bus. When DIR = H and G = L, SAB = H routes stored A data to B bus; when DIR = L and G = L, SBA = H routes stored B data to A bus - enabling flexible multiplexed data forwarding.
Is CY74FCT646ATQCT pin-compatible with older CY74FCT646T variants?
Yes - CY74FCT646ATQCT shares identical pinout, package footprint (QSOP-24), and logic function with CY74FCT646TQCT and CY74FCT646CTQCT. The 'A' suffix denotes the 6.3 ns speed grade, but all three variants use the same DBQ package and terminal assignment per TI datasheet SCCS031A.
CY74FCT646ATQCT 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:
- 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-SSOP
CY74FCT646ATQCT FAQ
1.How can I place an order for CY74FCT646ATQCT through Aetrix?
Please submit a Request for Quotation (RFQ) for CY74FCT646ATQCT 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 CY74FCT646ATQCT reliable?
The price and inventory of CY74FCT646ATQCT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CY74FCT646ATQCT is usually 5 days.
3.What payment methods are accepted for CY74FCT646ATQCT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CY74FCT646ATQCT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CY74FCT646ATQCT?
CY74FCT646ATQCT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CY74FCT646ATQCT 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 CY74FCT646ATQCT?
For technical support, including CY74FCT646ATQCT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CY74FCT646ATQCT requirements.
6.How does Aetrix verify that CY74FCT646ATQCT is sourced from the original manufacturer or authorized distributors?
All CY74FCT646ATQCT 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 CY74FCT646ATQCT meets industry standards.
7.What is the process for return or replacement of CY74FCT646ATQCT?
All CY74FCT646ATQCT units undergo pre-shipment inspection (PSI). If there is an issue with CY74FCT646ATQCT, 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 CY74FCT646ATQCT part is unused and in its original packaging.
Return procedure for CY74FCT646ATQCT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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