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Texas Instruments SN74ACT7881-30PN
- Part No.:
- SN74ACT7881-30PN
- Manufacturer:
- Texas Instruments
- Category:
- FIFOs Memory
- Package:
- 80-LQFP
- Datasheet:
-
SN74ACT7881-30PN.pdf
- Description:
- IC FIFO SYNC 1KX18 18NS 80LQFP
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
SN74ACT7881-30PN from Texas Instruments is a clocked first-in, first-out (FIFO) memory IC with 1024 × 18-bit organization, 33.4 MHz maximum clock frequency, 18 ns propagation delay (RDCLK→Q), and programmable almost-full/almost-empty flag. It supports independent asynchronous read/write operations synchronized to separate system clocks and is used in high-speed data buffering between mismatched bus domains in telecom and industrial controllers.
For engineers reviewing the SN74ACT7881-30PN datasheet, SN74ACT7881-30PN pinout, SN74ACT7881-30PN application, or SN74ACT7881-30PN equivalent, key selection criteria include its 80-pin shrink quad flat package (PN), 18-bit parallel I/O, dual-clock domain synchronization, programmable AF/AE offset, and compatibility with SN74ACT7882/SN74ACT7884 for depth/width expansion.
Technical Context
The SN74ACT7881-30PN implements a synchronous FIFO architecture with independent write and read pointer logic, reset-synchronized status flag initialization, and dual-clock domain control. It features dedicated WRTCLK/RDCLK inputs, paired enable signals (WRTEN1/WRTEN2, RDEN1/RDEN2), and three-level flag generation (AF/AE, HF, IR, OR) driven synchronously to their respective clocks.
Its status flags-AF/AE (programmable boundary), HF (512-word threshold), IR (write-ready), and OR (read-ready)-are generated using internal pointer comparison logic and latched on clock edges. The DAF input enables user-defined AF/AE offset programming during reset via D0–D8, while default X = 256 is applied when DAF is held high.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Depth × Width | 1024 × 18 bits - provides 18.4 kbit buffer capacity for burst-mode data alignment |
| Max Clock Frequency | 33.4 MHz - supports sustained 33.4 Mwords/s throughput per domain (WRTCLK or RDCLK) |
| Access Time | 11 ns @ 50-pF load - ensures timing margin for 33-MHz operation with standard PCB trace loading |
| Propagation Delay | 18 ns max (RDCLK↑ → Q) - defines worst-case latency from read clock edge to valid output data |
| Supply Voltage | 4.5 V to 5.5 V - compatible with 5-V TTL/CMOS logic families and industrial power rails |
| I/O Drive Strength | –8 mA / +16 mA - enables direct connection to 5-V buses without external line drivers |
| Operating Temperature | 0°C to 70°C - rated for commercial and industrial ambient environments |
Pinout & Package
SN74ACT7881-30PN uses an 80-pin shrink quad flat package (PN) with 0.5-mm lead pitch and exposed thermal pad. Pin numbering follows standard QFP convention with corner pin 1 marked.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (RESET) | Asynchronous reset input | Active-low signal that initializes read/write pointers and sets all status flags to known states (IR/OF low, AF/AE high) |
| 2 (OE) | Output enable input | Controls Q0–Q17 tri-state; outputs enter high-Z when OE = low, enabling shared bus operation |
| 3,4 (RDEN2,RDEN1) | Read enable inputs | Must both be high before RDCLK rising edge to gate data transfer from FIFO to outputs |
| 5 (RDCLK) | Read clock input | Free-running clock that synchronizes all read operations and OR/IR flag updates |
| 27 (DAF) | Define-almost-full input | Configures AF/AE offset during reset: low = program X from D8–D0; high = use default X = 256 |
| 29–31 (WRTCLK,WRTEN1,WRTEN2) | Write clock and enables | Control write timing and gating; WRTEN1/WRTEN2 must be high before WRTCLK rising edge |
| 33 (AF/AE) | Status flag output | Open-drain output indicating FIFO fill level relative to programmable threshold (X+1 or 1025−X words) |
| 35 (IR) | Input-ready flag | High when FIFO has space for at least one more word; used for handshake-driven write flow control |
| 36 (HF) | Half-full flag | High when ≥512 words stored; useful for early warning of buffer saturation |
| 38–39,41–42,44,46–47,49–50,52–53,55–56,58–59,61,63–64 (Q0–Q17) | Data outputs | 18-bit noninverting parallel outputs; driven only when OE, RDEN1, RDEN2, and OR are high |
| 66 (OR) | Output-ready flag | High when ≥1 word available; used for handshake-driven read flow control |
| 26–19,17,15–7 (D0–D17) | Data inputs | 18-bit parallel inputs capturing data on WRTCLK rising edge when IR, WRTEN1, WRTEN2 are high |
Key Features
| Feature | Design Value |
|---|---|
| Independent asynchronous read/write domains | Enables bridging of systems with different clock frequencies (e.g., DSP ↔ microcontroller) without external synchronization logic |
| Programmable AF/AE flag with user-defined offset | Allows precise tuning of flow-control thresholds (X = 0–255) to match application-specific latency and buffer utilization requirements |
| Expandable in word width and depth | Supports cascaded configurations up to 1024 × N bits (width) or M × 18 bits (depth) using standard control signal interconnection |
| Fast 11-ns access time with 50-pF load | Meets timing closure for 33-MHz operation on typical FR-4 PCBs with moderate trace capacitance |
| High-output drive (–8/+16 mA) | Drives 5-V TTL loads directly, eliminating need for bus transceivers in many embedded interfaces |
Applications
| Telecom Line Card Buffering | Industrial PLC Data Aggregation |
|---|---|
Use Scenario: Buffering packetized voice/data between TDM interface and packet-processing ASIC operating at different clock rates. IC Role / Device Role / Timing Role: Clock-domain crossing FIFO that absorbs jitter and rate mismatches between E1/T1 framers and Ethernet MAC layers. Use Value: Eliminates data loss during clock skew events and enables deterministic latency control via AF/AE flag-triggered DMA requests. |
Use Scenario: Consolidating sensor readings from multiple analog input modules into a central controller with variable scan cycle times. IC Role / Device Role / Timing Role: Asynchronous data collector that decouples fixed-rate ADC sampling from variable-interval CPU polling. Use Value: Prevents sample overrun during CPU interrupt latency spikes using IR flag-based write gating and HF flag for predictive buffer management. |
| Test Equipment Pattern Memory | Video Frame Synchronization |
Use Scenario: Storing stimulus patterns for automated test equipment where pattern generator and DUT clocks are unrelated. IC Role / Device Role / Timing Role: High-reliability FIFO providing glitch-free pattern delivery despite clock domain boundaries. Use Value: Ensures bit-accurate pattern replay by leveraging RESET-synchronized pointer initialization and AF/AE flag for pre-fill verification. |
Use Scenario: Aligning video pixel streams between camera sensor (MIPI CSI-2) and display controller (LVDS) with independent pixel clocks. IC Role / Device Role / Timing Role: Pixel-data FIFO absorbing phase drift and frame-rate differences between capture and render pipelines. Use Value: Maintains frame integrity using OR/IR handshaking and HF flag to trigger adaptive line buffering in downstream scaler logic. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar FIFO memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ACT7882-30PN | Same 1024 × 18 architecture but with 16-bit data width (D0–D15, Q0–Q15); lacks D16/D17 and associated pins | Suitable for 16-bit bus systems; not pin-compatible due to reduced I/O count and different pin mapping | Select when 16-bit width suffices and board layout allows pinout revision |
| SN74ACT7884-30PN | Same 1024 × 18 organization but includes additional status registers and extended control logic for daisy-chain configuration | Optimized for multi-FIFO depth expansion; requires modified reset and flag-handling firmware | Choose for systems requiring >1024-word depth with automatic pointer chaining across devices |
Compared with SN74ACT7882-30PN and SN74ACT7884-30PN, the SN74ACT7881-30PN offers full 18-bit I/O support and simpler status flag logic, making it optimal for applications needing maximum data width without advanced chaining features or where pin compatibility with legacy 18-bit designs is required.
Availability
SN74ACT7881-30PN is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLCs, and automated test equipment requiring stable component supply and long-term obsolescence management.
Supply support for SN74ACT7881-30PN 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 SN74ACT7881-30PN belongs to TI's Widebus™ family of high-speed CMOS FIFOs, designed specifically for robust clock-domain crossing in industrial, telecom, and instrumentation systems demanding deterministic latency and expandable buffering.
FAQ
What is the maximum operating frequency of the SN74ACT7881-30PN?
The SN74ACT7881-30PN supports a maximum clock frequency of 33.4 MHz for both WRTCLK and RDCLK inputs, as specified in the timing requirements table for the -30 speed grade. This rating assumes operation within recommended conditions (VCC = 4.5 V to 5.5 V, TA = 0°C to 70°C) and CL = 50 pF. The device achieves this performance with 18 ns maximum propagation delay from clock to output.
How is the AF/AE flag programmed on the SN74ACT7881-30PN?
The AF/AE flag on the SN74ACT7881-30PN is programmed during reset using the DAF input and D0–D8 data lines. To set a custom offset X, hold DAF low, apply the 9-bit value (X) to D0–D8, then pulse RESET low-to-high. To use the default X = 256, hold DAF high during RESET assertion. The programmed value persists until next reset and determines the fill-level thresholds for AF/AE assertion.
Does the SN74ACT7881-30PN support expansion beyond 1024 × 18 bits?
Yes, the SN74ACT7881-30PN supports both word-width and word-depth expansion. For width expansion (e.g., 1024 × 36), connect control signals in parallel and combine D/Q buses. For depth expansion (e.g., 2048 × 18), cascade devices using IR→WRTEN and OR→RDEN handshaking. The datasheet confirms expandability in both dimensions using standard pin interconnections without external logic.
What are the key timing parameters for read operations on the SN74ACT7881-30PN?
For read operations, the SN74ACT7881-30PN requires OE, RDEN1, and RDEN2 to be high before the RDCLK rising edge. Setup time is 5 ns minimum; hold time is 0 ns. Propagation delay from RDCLK↑ to valid Q output is 18 ns maximum. The OR flag becomes valid 12 ns after RDCLK↑, and HF transitions within 21 ns. All values are specified for CL = 50 pF and VCC = 4.5–5.5 V.
Is the SN74ACT7881-30PN pin-compatible with other members of the SN74ACT788x family?
The SN74ACT7881-30PN is explicitly stated as pin-to-pin compatible with SN74ACT7882 and SN74ACT7884 in the datasheet. However, functional differences exist: SN74ACT7882 omits D16/D17 and Q16/Q17 pins, while SN74ACT7884 adds enhanced chaining logic. Physical pin count and location match across all three PN-package variants, enabling drop-in replacement where functional requirements align.
SN74ACT7881-30PN 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:
- 33.4MHz
- Access Time:
- 18ns
- 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:
- 80-LQFP (12x12)
SN74ACT7881-30PN FAQ
1.How can I place an order for SN74ACT7881-30PN through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ACT7881-30PN 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 SN74ACT7881-30PN reliable?
The price and inventory of SN74ACT7881-30PN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ACT7881-30PN is usually 5 days.
3.What payment methods are accepted for SN74ACT7881-30PN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ACT7881-30PN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ACT7881-30PN?
SN74ACT7881-30PN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ACT7881-30PN 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 SN74ACT7881-30PN?
For technical support, including SN74ACT7881-30PN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ACT7881-30PN requirements.
6.How does Aetrix verify that SN74ACT7881-30PN is sourced from the original manufacturer or authorized distributors?
All SN74ACT7881-30PN 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 SN74ACT7881-30PN meets industry standards.
7.What is the process for return or replacement of SN74ACT7881-30PN?
All SN74ACT7881-30PN units undergo pre-shipment inspection (PSI). If there is an issue with SN74ACT7881-30PN, 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 SN74ACT7881-30PN part is unused and in its original packaging.
Return procedure for SN74ACT7881-30PN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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