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Texas Instruments SN74ACT7811-20PN
- Part No.:
- SN74ACT7811-20PN
- Manufacturer:
- Texas Instruments
- Category:
- FIFOs Memory
- Package:
- 80-LQFP
- Datasheet:
-
SN74ACT7811-20PN.pdf
- Description:
- IC FIFO SYNC 1KX18 20NS 80LQFP
- Quantity:
- Payment:
- Shipping:
Inventory:3,226
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Product details
Overview
SN74ACT7811-20PN from Texas Instruments is a 1024 × 18-bit clocked first-in, first-out (FIFO) memory IC with independent asynchronous read/write clocks, 20 ns access time, programmable almost-full/almost-empty flag, and 80-pin thin quad flat package. It enables high-speed data buffering between mismatched bus domains in telecom line cards and industrial protocol gateways.
For engineers reviewing the SN74ACT7811-20PN datasheet, SN74ACT7811-20PN pinout, SN74ACT7811-20PN application, or SN74ACT7811-20PN equivalent, key selection criteria include dual-clock synchronization capability, 18-bit parallel I/O width, 0°C to 70°C operating range, and compatibility with ACT logic voltage levels (4.5–5.5 V).
Technical Context
The SN74ACT7811-20PN implements a synchronous FIFO architecture with separate write clock (WRTCLK) and read clock (RDCLK) domains, each driving independent pointer logic. Its internal 1024-word × 18-bit RAM array supports concurrent write and read operations without arbitration overhead.
Flag generation is fully hardware-based: HF (half-full), IR (input-ready), OR (output-ready), and programmable AF/AE (almost-full/almost-empty) are generated synchronously to their respective clocks. The DAF input allows dynamic configuration of the AF/AE offset value during reset.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory depth × width | 1024 words × 18 bits - provides 18.4 kbit buffer capacity for burst-mode data alignment |
| Access time | 20 ns at 50-pF load - guarantees deterministic latency for real-time packet buffering |
| Max clock frequency | 28.5 MHz - supports sustained 513 Mbps throughput on 18-bit bus |
| Supply voltage | 4.5 V to 5.5 V - compatible with standard 5-V TTL/ACT logic systems |
| Operating temperature | 0°C to 70°C - rated for commercial-grade industrial control and networking equipment |
| Output drive | –8 mA / +16 mA - sufficient to directly drive 50-Ω transmission lines or multiple CMOS inputs |
| Power dissipation capacitance | 65 pF per 1K bits - enables accurate dynamic power estimation at 5 MHz operation |
Pinout & Package
SN74ACT7811-20PN uses an 80-pin thin quad flat package (PN), JEDEC MS-026 compliant, with 0.5 mm pitch and 12.2 mm × 12.2 mm body size. Pin 1 is located at top-left corner (marked by beveled edge), and pins are numbered counter-clockwise.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| D0–D17 | Data inputs | 18-bit parallel write data bus; also carry AF/AE offset value when DAF transitions low |
| Q0–Q17 | Data outputs | 18-bit parallel read data bus; noninverting relative to inputs; high-impedance when OE = low |
| WRTCLK, RDCLK | Clock inputs | Free-running write/read synchronization clocks; rising-edge triggered; support independent domain timing |
| WRTEN1/WRTEN2, RDEN1/RDEN2 | Enable inputs | Two-input AND logic per domain ensures glitch-immune write/read gating before clock edge |
| OE | Output enable | Active-high control for Q0–Q17 tri-state; must be asserted before RDCLK rising edge to avoid bus contention |
| RESET | Asynchronous reset | Initializes pointers and flags; requires ≥4 WRTCLK/RDCLK cycles; defines AF/AE behavior based on DAF state |
| DAF | Define AF/AE | Input that selects default (X=256) or user-defined AF/AE offset during reset cycle |
| AF/AE, HF, IR, OR | Status flags | Open-drain outputs indicating FIFO fill level; synchronized to respective clock domains for metastability immunity |
Key Features
| Feature | Design Value |
|---|---|
| Independent read/write clocks | Eliminates need for external clock domain crossing logic; simplifies interface between 25-MHz processor and 33-MHz peripheral bus |
| Programmable AF/AE flag | Allows tuning of flow-control thresholds (e.g., X=128 for low-latency streaming vs. X=384 for jitter absorption) |
| Cascadable in width and depth | Enables 1024×36-bit or 2048×18-bit configurations using identical control logic and timing constraints |
| Input/output-ready flags | IR and OR provide ready-to-write/ready-to-read handshaking without polling, reducing CPU overhead in interrupt-driven drivers |
| High-output drive strength | Directly interfaces to backplane traces or multi-drop buses without external buffers, saving PCB area and BOM cost |
Applications
| Telecom Line Card Buffering | Industrial Protocol Gateway |
|---|---|
|
Use Scenario: Absorbing burst traffic between TDM framer and packet-switching ASIC in DSLAM line cards. IC Role / Device Role / Timing Role: Clock-domain bridging FIFO with independent 25-MHz write (framer) and 33-MHz read (ASIC) clocks. Use Value: Prevents data loss during clock skew or jitter; 20 ns access time ensures sub-microsecond latency for real-time voice frames. |
Use Scenario: Translating Modbus RTU serial data to EtherNet/IP packets in factory-floor gateways. IC Role / Device Role / Timing Role: Asynchronous data staging buffer between UART controller (115.2 kbps) and Ethernet MAC (100 Mbps). Use Value: Decouples slow serial input from high-speed network stack; IR/OR flags enable zero-waitstate DMA transfers. |
| Test Equipment Data Capture | Medical Imaging Interface |
|
Use Scenario: Capturing high-speed analog-to-digital samples from oscilloscope front-end before host PC transfer. IC Role / Device Role / Timing Role: High-throughput FIFO with 28.5 MHz write clock (ADC interface) and 25 MHz read clock (PCI bus). Use Value: Sustains 513 Mbps capture rate without overflow; programmable AF/AE triggers early DMA request at 75% fill level. |
Use Scenario: Buffering ultrasound image frame data between beamformer ASIC and JPEG compression engine. IC Role / Device Role / Timing Role: 18-bit wide FIFO synchronizing 40-MHz pixel stream (beamformer) with 20-MHz compression core. Use Value: Half-full flag (HF) signals compression start point; cascaded depth expansion supports full-frame buffering (2048×18-bit). |
Equivalent & Alternatives
The following parts are listed as comparable options for similar FIFO memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ACT7881-20PN | Same 1024×18 architecture but lacks DAF-programmable AF/AE; fixed offset at X=256 | Reduced flexibility in flow-control threshold tuning; suitable only where fixed 25%–75% fill window suffices | Select when AF/AE programmability is unnecessary and legacy design reuse is prioritized |
| IDT7203L15TPG | 1024×9-bit depth, 15 ns access, 5-V supply; requires two devices for 18-bit width; different flag encoding | Higher component count and routing complexity for same data width; incompatible pinout and timing margins | Choose only if existing IDT-based designs mandate footprint compatibility over single-chip integration |
Compared with SN74ACT7881-20PN, SN74ACT7811-20PN adds runtime AF/AE reconfiguration via DAF-critical for adaptive buffer management-while IDT7203L15TPG demands board-level redesign to match 18-bit I/O, increasing validation effort and signal integrity risk.
Availability
SN74ACT7811-20PN is available at Aetrix Electronics and suitable for telecom infrastructure, industrial automation, and test equipment requiring stable component supply with long-lifecycle support.
Supply support for SN74ACT7811-20PN 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 and memory products.
The SN74ACT7811-20PN belongs to TI's Widebus™ family of high-speed FIFOs, engineered specifically for clock-domain isolation and burst-data buffering in communications and industrial control systems.
FAQ
What is the maximum operating frequency of the SN74ACT7811-20PN?
The SN74ACT7811-20PN supports a maximum clock frequency of 28.5 MHz for both WRTCLK and RDCLK inputs under recommended operating conditions (VCC = 4.5 V to 5.5 V, TA = 0°C to 70°C). This rating is derived from its 20 ns access time specification and verified across process corners and voltage extremes.
How does the AF/AE flag programming work on the SN74ACT7811-20PN?
The AF/AE flag on the SN74ACT7811-20PN is programmed during reset: holding DAF low while pulsing RESET configures AF/AE using the binary value on D0–D8 as the offset X; holding DAF high selects the default X = 256. The SN74ACT7811-20PN applies this setting immediately after reset completion and retains it until next reset.
Is the SN74ACT7811-20PN pin-compatible with other members of the SN74ACT78xx family?
Yes, the SN74ACT7811-20PN is pin-to-pin compatible with SN74ACT7881, SN74ACT7882, and SN74ACT7884 in the same PN package, sharing identical pin functions and electrical characteristics-enabling drop-in replacement where feature set alignment permits.
What are the thermal and packaging specifications for the SN74ACT7811-20PN?
The SN74ACT7811-20PN uses an 80-pin thin quad flat package (PN) compliant with JEDEC MS-026, measuring 12.2 mm × 12.2 mm with 0.5 mm lead pitch. It is characterized for operation from 0°C to 70°C ambient and has no specified MSL rating due to its obsolete status, though standard moisture-sensitive handling applies.
Can the SN74ACT7811-20PN be used in depth-expanded configurations?
Yes, the SN74ACT7811-20PN supports word-depth expansion: cascading N devices yields 1024×N × 18-bit capacity. Timing adjusts linearly-first output appears after (N × 3) RDCLK cycles, and IR recovery after (N × 2) WRTCLK cycles-ensuring predictable behavior in multi-chip buffers.
SN74ACT7811-20PN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ACT
- Package/Case:
- 80-LQFP
- Packaging:
- Tray
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Size:
- 18K (1K x 18)
- Function:
- Synchronous
- Data Rate:
- 28.5MHz
- Access Time:
- 20ns
- Voltage - Supply:
- 4.5 V ~ 5.5 V
- Current - Supply (Max):
- 1mA
- Bus Directional:
- Uni-Directional
- Expansion Type:
- Depth, Width
- Programmable Flags Support:
- Yes
- Retransmit Capability:
- No
- FWFT Support:
- No
- Operating Temperature:
- 0°C ~ 70°C
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 80-LQFP (12x12)
SN74ACT7811-20PN FAQ
1.How can I place an order for SN74ACT7811-20PN through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ACT7811-20PN 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 SN74ACT7811-20PN reliable?
The price and inventory of SN74ACT7811-20PN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ACT7811-20PN is usually 5 days.
3.What payment methods are accepted for SN74ACT7811-20PN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ACT7811-20PN transactions.
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4.How is shipping managed for SN74ACT7811-20PN?
SN74ACT7811-20PN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ACT7811-20PN 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 SN74ACT7811-20PN?
For technical support, including SN74ACT7811-20PN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ACT7811-20PN requirements.
6.How does Aetrix verify that SN74ACT7811-20PN is sourced from the original manufacturer or authorized distributors?
All SN74ACT7811-20PN 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 SN74ACT7811-20PN meets industry standards.
7.What is the process for return or replacement of SN74ACT7811-20PN?
All SN74ACT7811-20PN units undergo pre-shipment inspection (PSI). If there is an issue with SN74ACT7811-20PN, 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 SN74ACT7811-20PN part is unused and in its original packaging.
Return procedure for SN74ACT7811-20PN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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