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Texas Instruments CY74FCT821BTSOCT
- Part No.:
- CY74FCT821BTSOCT
- Manufacturer:
- Texas Instruments
- Category:
- Flip Flops
- Package:
- 24-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
CY74FCT821BTSOCT.pdf
- Description:
- IC FF D-TYPE SNGL 10BIT 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,664
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Product details
Overview
CY74FCT821BTSOCT from Texas Instruments is a 10-bit positive-edge-triggered bus-interface register with 3-state outputs, designed for high-capacitance load drive and low-bus-loading operation in address/data path buffering. It features 64-mA sink / 32-mA source output drive, Ioff partial-power-down support, and 7.5-ns propagation delay (tPLH/tPHL) at 50 pF load - ideal for industrial control I/O expansion and memory interface buffering.
For engineers reviewing the CY74FCT821BTSOCT datasheet, CY74FCT821BTSOCT pinout, CY74FCT821BTSOCT application, or CY74FCT821BTSOCT equivalent, key selection criteria include its TTL-compatible input/output levels, matched rise/fall times, edge-rate controlled noise performance, and SOIC-24 package compatibility with legacy FCT-family layouts.
Technical Context
This device implements ten independent D-type flip-flops clocked on the low-to-high transition of CP, with synchronous 3-state output control via OE. Its Ioff circuitry actively disables outputs during VCC = 0 V to prevent backflow current, enabling safe partial-power-down operation in mixed-voltage systems.
It uses FCT-family silicon with reduced VOH (typically 3.3 V at IOH = –15 mA), edge-rate control for EMI suppression, and full TTL-level compatibility - supporting direct interfacing with legacy 5-V logic without level translation while maintaining low input/output capacitance (Ci = 5–10 pF, Co = 9–12 pF).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Function | 10-bit positive-edge-triggered D-type register with 3-state outputs |
| Propagation Delay | 7.5 ns max (CP→Y, CL = 50 pF) - enables ≤133-MHz clock operation in buffered data paths |
| Output Drive | 64 mA sink / 32 mA source - drives heavy capacitive buses (e.g., >100 pF) without signal degradation |
| Ioff Support | Active at VCC = 0 V - blocks reverse current flow during power sequencing or hot-swap scenarios |
| Supply Voltage | 4.75 V to 5.25 V - ensures stable operation across industrial-grade 5-V rails with ±5% tolerance |
| Input Compatibility | Fully TTL-compatible VIH = 2 V, VIL = 0.8 V - interoperates with 74LS, 74ALS, and other legacy 5-V logic families |
| ESD Rating | 2000-V HBM, 200-V MM, 1000-V CDM - meets JEDEC JESD22-A114/A115/C101 for robust board-level handling |
Pinout & Package
Package: SOIC-24 (DW), 7.5 mm × 15.4 mm body, gull-wing leads, RoHS-compliant NIPDAU finish, MSL Level-1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 | D0–D9 Data Inputs | Asynchronous parallel data inputs to D-type flip-flops; CMOS/TTL-compatible voltage thresholds |
| 11 | OE Output Enable | Active-low control: OE = L enables Y0–Y9 outputs; OE = H places all outputs in high-impedance state |
| 12 | GND | Ground reference for logic and power domains; must be connected to system common ground plane |
| 13–22 | Y0–Y9 Outputs | 3-state buffered register outputs; low-capacitance (Co ≤ 12 pF) in Z-state minimizes bus loading |
| 23 | CP Clock Pulse | Positive-edge-triggered clock input; latches D0–D9 simultaneously on rising edge |
| 24 | VCC | 5-V supply pin; requires local 0.1-µF ceramic decoupling adjacent to pin per TI layout guidelines |
Key Features
| Feature | Design Value |
|---|---|
| Edge-Rate Controlled Outputs | Slower edge transitions reduce simultaneous switching noise (SSN) and radiated EMI in dense PCB layouts |
| Matched Rise/Fall Times | tPLH ≈ tPHL ensures symmetrical waveform timing - critical for setup/hold margin in synchronous bus designs |
| Low Input Capacitance | Ci = 5–10 pF minimizes loading on upstream drivers, preserving signal integrity in fan-out chains |
| TTL-Compatible Thresholds | VIH = 2 V / VIL = 0.8 V allows direct connection to 74LS/ALS without level-shifting circuitry |
| Partial-Power-Down Safe | Ioff < ±1 µA at VCC = 0 V prevents backfeed into powered sections during staggered power-up/down sequences |
Applications
| Industrial PLC I/O Expansion | Legacy Memory Bus Buffering |
|---|---|
Use Scenario: Expanding digital I/O points in programmable logic controllers using shared backplane buses with multiple 5-V peripherals. IC Role / Device Role / Timing Role: Acts as a synchronized output port latch, capturing CPU writes on CP edge and driving high-current loads (e.g., relay drivers, LED arrays) via Y0–Y9. Use Value: 64-mA sink capability directly drives 20-mA LEDs or 10-mA optocouplers without external transistors; Ioff prevents backfeed during module hot-swap. | Use Scenario: Buffering 10-bit address/data lines between microcontroller and older SRAM/EPROM chips with strict timing margins. IC Role / Device Role / Timing Role: Provides registered, 3-state-controlled data staging between processor and memory - isolating bus segments during read/write cycles. Use Value: 7.5-ns tPLH ensures reliable timing closure in 133-MHz-equivalent bus cycles; matched edges preserve data eye width across all 10 bits. |
| Automotive Body Control Module | Test Equipment Digital Pattern Generator |
Use Scenario: Managing discrete sensor inputs and actuator outputs in automotive BCMs where mixed-voltage subsystems require isolation during sleep/wake transitions. IC Role / Device Role / Timing Role: Serves as a fault-tolerant interface register - holding last-known state during VCC brownout and re-enabling cleanly on recovery. Use Value: Ioff protection eliminates risk of current injection into unpowered CAN/LIN domain supplies; 2000-V HBM withstands vehicle ESD events. | Use Scenario: Generating precise, synchronized multi-bit stimulus patterns for IC functional testing in ATE systems with tight skew requirements. IC Role / Device Role / Timing Role: Delivers deterministic, edge-aligned 10-bit vectors on each CP rising edge - acting as a pattern latch stage before driver amplification. Use Value: 1.5-ns minimum hold time (th) and 3-ns setup (tsu) enable sub-10-ns timing resolution; low-output skew (<0.5 ns typical) maintains vector integrity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus-interface register applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| CY74FCT821CTSOCT | 6-ns propagation delay (vs. 7.5 ns), higher drive (64 mA sink / 32 mA source unchanged), same SOIC-24 package | Better timing margin for ≥166-MHz-equivalent buses; identical pinout and logic behavior | Select when tighter tPLH/tPHL is required without changing layout or firmware |
| SN74FCT821ATSOCT | 10-ns propagation delay, lower drive (48 mA sink / 24 mA source), same SOIC-24 footprint | Reduced speed/power trade-off for cost-sensitive, lower-frequency systems (≤100 MHz) | Choose for legacy designs where timing slack exists and BOM cost optimization is prioritized |
Compared with CY74FCT821BTSOCT, CY74FCT821CTSOCT offers faster timing but identical functionality and layout, while SN74FCT821ATSOCT provides slower, lower-power operation - enabling design flexibility across performance tiers without PCB redesign.
Availability
CY74FCT821BTSOCT is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, legacy memory bus buffering, and automotive body control modules requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for CY74FCT821BTSOCT 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 delivering analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
CY74FCT821BTSOCT belongs to TI's FCT logic family - engineered for high-speed, low-noise 5-V bus interfacing with robust ESD immunity and partial-power-down safety in mission-critical embedded systems.
FAQ
What is the maximum clock frequency supported by CY74FCT821BTSOCT?
CY74FCT821BTSOCT supports a maximum clock frequency of approximately 133 MHz, derived from its 7.5-ns maximum propagation delay (tPLH/tPHL) under CL = 50 pF conditions. This assumes sufficient setup (3 ns) and hold (1.5 ns) timing margins are maintained in the target system layout and loading environment.
Does CY74FCT821BTSOCT require external pull-up or pull-down resistors on unused inputs?
Yes - per TI's recommended operating conditions, all unused inputs of CY74FCT821BTSOCT must be held at either VCC or GND to ensure predictable logic states and prevent floating-node-induced current leakage or oscillation. Leaving inputs unconnected may cause increased ICC or erratic register behavior.
Can CY74FCT821BTSOCT operate safely with VCC = 3.3 V?
No - CY74FCT821BTSOCT is specified only for VCC = 4.75 V to 5.25 V. Operation at 3.3 V falls outside its recommended operating conditions and risks failure to meet VOH/VOL, timing, or noise immunity specifications. For 3.3-V systems, consider TI's ALVC or LVC series alternatives.
What is the thermal resistance (θJA) of CY74FCT821BTSOCT in its SOIC-24 package?
The junction-to-ambient thermal resistance (θJA) for CY74FCT821BTSOCT in the SOIC-24 (DW) package is 46°C/W, as specified in TI's absolute maximum ratings. This value assumes standard JEDEC test board conditions (JESD 51-7); actual board-level θJA will vary based on copper area, layer count, and airflow.
How does the Ioff feature of CY74FCT821BTSOCT protect downstream circuitry during power-down?
The Ioff feature in CY74FCT821BTSOCT disables all outputs when VCC = 0 V, limiting leakage current to ±1 µA even if signals remain present on D, CP, or OE pins. This prevents damaging reverse current flow into unpowered sections of the system - a critical safeguard during hot-swap, partial-power-down, or mixed-rail sequencing scenarios.
CY74FCT821BTSOCT 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:
- Obsolete
- Function:
- Standard
- Type:
- D-Type
- Output Type:
- Tri-State, Non-Inverted
- Number of Elements:
- 1
- Number of Bits per Element:
- 10
- Clock Frequency:
- -
- Max Propagation Delay @ V, Max CL:
- 15ns @ 5V, 300pF
- Trigger Type:
- Positive Edge
- Current - Output High, Low:
- 32mA, 64mA
- Voltage - Supply:
- 4.75V ~ 5.25V
- Current - Quiescent (Iq):
- 200 µA
- Input Capacitance:
- 5 pF
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-SOIC
CY74FCT821BTSOCT FAQ
1.How can I place an order for CY74FCT821BTSOCT through Aetrix?
Please submit a Request for Quotation (RFQ) for CY74FCT821BTSOCT 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 CY74FCT821BTSOCT reliable?
The price and inventory of CY74FCT821BTSOCT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CY74FCT821BTSOCT is usually 5 days.
3.What payment methods are accepted for CY74FCT821BTSOCT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CY74FCT821BTSOCT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CY74FCT821BTSOCT?
CY74FCT821BTSOCT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CY74FCT821BTSOCT 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 CY74FCT821BTSOCT?
For technical support, including CY74FCT821BTSOCT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CY74FCT821BTSOCT requirements.
6.How does Aetrix verify that CY74FCT821BTSOCT is sourced from the original manufacturer or authorized distributors?
All CY74FCT821BTSOCT 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 CY74FCT821BTSOCT meets industry standards.
7.What is the process for return or replacement of CY74FCT821BTSOCT?
All CY74FCT821BTSOCT units undergo pre-shipment inspection (PSI). If there is an issue with CY74FCT821BTSOCT, 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 CY74FCT821BTSOCT part is unused and in its original packaging.
Return procedure for CY74FCT821BTSOCT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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