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Texas Instruments SN74ACT7881-20FN
- Part No.:
- SN74ACT7881-20FN
- Manufacturer:
- Texas Instruments
- Category:
- FIFOs Memory
- Package:
- 68-LCC (J-Lead)
- Datasheet:
-
SN74ACT7881-20FN.pdf
- Description:
- IC FIFO SYNC 1KX18 13NS 68PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:2,119
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Product details
Overview
SN74ACT7881-20FN from Texas Instruments is a clocked first-in, first-out (FIFO) memory IC with 1024 × 18-bit organization, 5-V supply operation, 11-ns access time at 50-pF load, independent asynchronous read/write clocks (RDCLK/WRTCLK), and programmable almost-full/almost-empty flag. It serves as a data buffering interface between mismatched-speed digital subsystems in high-throughput communication and control systems.
For engineers reviewing the SN74ACT7881-20FN datasheet, SN74ACT7881-20FN pinout, SN74ACT7881-20FN application, or SN74ACT7881-20FN equivalent, key selection considerations include its 68-pin PLCC (FN) package, 50-MHz maximum clock frequency, dual enable architecture (WRTEN1/WRTEN2, RDEN1/RDEN2), and status flag timing behavior under synchronous reset conditions.
Technical Context
The SN74ACT7881-20FN implements a fully synchronous FIFO core with independent read and write pointer logic, RAM array, and status-flag generation circuitry. Its dual-clock architecture allows RDCLK and WRTCLK to operate at different frequencies while maintaining data integrity across clock domains.
Status flags-including AF/AE (programmable boundary), HF (half-full), IR (input-ready), OR (output-ready), and DAF-controlled offset definition-are generated synchronously to their respective clocks and support precise buffer-level monitoring for flow control in real-time systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Depth × Width | 1024 × 18 bits - supports up to 18-bit parallel data streams with full-depth buffering |
| Access Time | 11 ns at 50-pF load - enables reliable operation at 50 MHz system clock rates |
| Supply Voltage | 4.5 V to 5.5 V - compatible with standard 5-V TTL/CMOS logic rails |
| Max Clock Frequency | 50 MHz - specified for SN74ACT7881-20 variant per timing table |
| Input/Output Drive | –8 mA / +16 mA - sufficient for direct bus interfacing without external buffers |
| Operating Temperature | 0°C to 70°C - commercial-grade thermal range for industrial and telecom equipment |
| Flag Outputs | AF/AE, HF, IR, OR - four dedicated status signals for autonomous flow control |
Pinout & Package
SN74ACT7881-20FN uses a 68-pin plastic leaded chip carrier (PLCC, FN package) with J-lead configuration and 0.05-inch pitch. The package is surface-mount compatible and thermally rated at θJA = 39°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (RESET) | Asynchronous reset input | Drives internal read/write pointers and status flags low; required at power-up |
| 5 (RDCLK) | Read clock input | Free-running edge-triggered clock for synchronized output data transfer |
| 29 (WRTCLK) | Write clock input | Free-running edge-triggered clock for synchronized input data capture |
| 2–4, 30–31 (OE, RDEN1, RDEN2, WRTEN1, WRTEN2) | Enable controls | Dual-enable architecture prevents spurious reads/writes; OE gates Q outputs |
| 33 (AF/AE) | Status output | Programmable flag indicating near-full/near-empty condition based on user-defined X offset |
| 35 (IR), 66 (OR) | Status outputs | IR asserts when FIFO has space; OR asserts when FIFO contains data - used for handshaking |
| D0–D17 (pins 7–19, 22–26) | Data inputs | 18-bit parallel input bus; D0–D8 also carry AF/AE offset value during DAF programming |
| Q0–Q17 (pins 38–39, 41–42, 44, 46–47, 49–50, 52–53, 55–56, 58–59, 61, 63–64) | Data outputs | Noninverting 18-bit parallel output bus; high-impedance when OE = low |
Key Features
| Feature | Design Value |
|---|---|
| Independent Read/Write Clocks | Enables seamless bridging between asynchronous subsystems (e.g., CPU ↔ DSP, UART ↔ DMA) |
| Programmable AF/AE Flag | Boundary configurable via DAF/D0–D8 during reset - supports custom flow-control thresholds |
| Expandable Architecture | Supports word-width (parallel) and word-depth (serial) expansion using standard control signal routing |
| Fast 11-ns Access Time | Meets timing requirements for 50-MHz clock domains with 50-pF load - reduces inter-stage latency |
| High-Drive Outputs | ±8/16 mA drive strength eliminates need for external bus transceivers in most 5-V backplane applications |
Applications
| Telecom Line Card Buffering | Industrial PLC Data Pipeline |
|---|---|
Use Scenario: Buffering variable-rate data between TDM framer and packet processor in DSLAM line cards. IC Role / Device Role / Timing Role: FIFO memory providing elastic storage between 8-kHz TDM and bursty Ethernet packet interfaces. Use Value: Prevents data loss during rate mismatches; AF/AE flag triggers DMA request before overflow/underflow. | Use Scenario: Interfacing motion controller FPGA with legacy I/O modules operating at different update rates. IC Role / Device Role / Timing Role: Synchronizing sensor acquisition (fast) and actuator command (slower) domains via dual-clock FIFO. Use Value: Eliminates metastability risk; IR/OR flags enable deterministic handshake without software polling. |
| Test Equipment Pattern Memory | Video Frame Synchronization |
Use Scenario: Storing stimulus patterns in automated test equipment where pattern generator and DUT clocks differ. IC Role / Device Role / Timing Role: Clocked FIFO acting as timing isolation layer between pattern sequencer and device-under-test interface. Use Value: Enables glitch-free pattern delivery; HF flag assists in optimizing test cycle timing alignment. | Use Scenario: Aligning video pixel streams from camera sensor (MIPI CSI-2) and display controller (LVDS) with independent pixel clocks. IC Role / Device Role / Timing Role: 1024×18 FIFO absorbing jitter and phase drift between source and sink pixel clocks. Use Value: Maintains frame continuity; programmable AF/AE allows dynamic buffer threshold tuning per resolution mode. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar FIFO memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ACT7882-20FN | Same 1024×18 organization, identical pinout, but lacks DAF and programmable AF/AE functionality | Suitable for fixed-threshold buffering only; no runtime AF/AE reconfiguration | Select when simplified flag logic suffices and cost reduction is prioritized |
| SN74ACT7884-20FN | 1024×9 organization - half the data width, same depth and timing specs | Used where 9-bit or narrower data paths exist; requires two devices for 18-bit width | Choose for lower pin count or when 9-bit granularity matches system bus architecture |
Compared with SN74ACT7882-20FN and SN74ACT7884-20FN, the SN74ACT7881-20FN uniquely provides programmable AF/AE flag behavior and full 18-bit width in a single device - critical for adaptive flow control and minimizing board space in high-bandwidth interfaces.
Availability
SN74ACT7881-20FN is available at Aetrix Electronics and suitable for telecom infrastructure, industrial automation, test equipment, and video synchronization applications requiring stable component supply and long-term obsolescence management.
Supply support for SN74ACT7881-20FN 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 digital interface components.
The SN74ACT7881-20FN belongs to TI's Widebus™ family of advanced logic FIFOs, designed specifically for high-speed, low-latency data buffering in multi-clock-domain digital systems.
FAQ
What is the maximum clock frequency supported by the SN74ACT7881-20FN?
The SN74ACT7881-20FN is rated for a maximum clock frequency of 50 MHz for both RDCLK and WRTCLK, as confirmed by the timing table for the -20 speed grade. This specification assumes proper setup/hold times, 4.5–5.5 V supply, and operation within 0°C to 70°C ambient temperature. The SN74ACT7881-20FN achieves this performance with 11-ns access time at 50-pF load, making it suitable for demanding real-time buffering applications.
How does the AF/AE flag programming work on the SN74ACT7881-20FN?
The AF/AE flag on the SN74ACT7881-20FN is programmed during reset using the DAF pin and D0–D8 inputs. When DAF transitions low, the binary value on D0–D8 is latched as the AF/AE offset (X). A subsequent RESET pulse defines the flag boundary. If DAF remains high during reset, the default X = 256 is used. This mechanism allows runtime configuration of full/empty thresholds without external logic, a capability unique to the SN74ACT7881-20FN among its pin-compatible variants.
Is the SN74ACT7881-20FN pin-compatible with other members of the SN74ACT788x family?
Yes, the SN74ACT7881-20FN is explicitly stated as pin-to-pin compatible with SN74ACT7882, SN74ACT7884, and SN74ACT7811 in the datasheet. All share the same 68-pin FN package footprint and identical signal assignments for core functions (clocks, enables, data I/O, flags). However, functional differences exist - notably the SN74ACT7881-20FN's DAF pin and programmable AF/AE - so PCB layout reuse is possible but firmware/hardware integration must account for feature divergence.
What are the key timing parameters that define SN74ACT7881-20FN read/write reliability?
Key timing parameters for the SN74ACT7881-20FN include: minimum setup time of 5 ns for WRTEN1/WRTEN2 before WRTCLK↑, 4 ns for OE/RDEN1/RDEN2 before RDCLK↑, and 5 ns for D0–D17 before WRTCLK↑. Hold times are zero for most signals post-edge. Propagation delays range from 3–13 ns (tpd) depending on path. These values ensure robust operation at 50 MHz and must be met in PCB layout and driver design to prevent metastability or data corruption in the SN74ACT7881-20FN.
Can the SN74ACT7881-20FN be used in word-width expansion configurations?
Yes, the SN74ACT7881-20FN supports word-width expansion by connecting multiple devices in parallel - for example, two SN74ACT7881-20FN units can implement a 1024×36-bit FIFO. Control signals (RDCLK, WRTCLK, enables, RESET) are shared across devices, while data buses (D0–D17, Q0–Q17) are concatenated. Status flags (IR, OR, HF, AF/AE) may be wired-OR'd or sampled from one unit. This capability is documented in the "Expanding the SN74ACT7881" section of the SN74ACT7881-20FN datasheet and verified in application figure 8.
SN74ACT7881-20FN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ACT
- Package/Case:
- 68-LCC (J-Lead)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Size:
- 18K (1K x 18)
- Function:
- Synchronous
- Data Rate:
- 50MHz
- Access Time:
- 13ns
- Voltage - Supply:
- 4.5 V ~ 5.5 V
- Current - Supply (Max):
- 400µA
- 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:
- 68-PLCC (24.23x24.23)
SN74ACT7881-20FN FAQ
1.How can I place an order for SN74ACT7881-20FN through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ACT7881-20FN 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 SN74ACT7881-20FN reliable?
The price and inventory of SN74ACT7881-20FN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ACT7881-20FN is usually 5 days.
3.What payment methods are accepted for SN74ACT7881-20FN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ACT7881-20FN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ACT7881-20FN?
SN74ACT7881-20FN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ACT7881-20FN 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 SN74ACT7881-20FN?
For technical support, including SN74ACT7881-20FN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ACT7881-20FN requirements.
6.How does Aetrix verify that SN74ACT7881-20FN is sourced from the original manufacturer or authorized distributors?
All SN74ACT7881-20FN 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 SN74ACT7881-20FN meets industry standards.
7.What is the process for return or replacement of SN74ACT7881-20FN?
All SN74ACT7881-20FN units undergo pre-shipment inspection (PSI). If there is an issue with SN74ACT7881-20FN, 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 SN74ACT7881-20FN part is unused and in its original packaging.
Return procedure for SN74ACT7881-20FN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SN74ACT7881-20FN Tags
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