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Texas Instruments SN74ACT3631-15PCB
- Part No.:
- SN74ACT3631-15PCB
- Manufacturer:
- Texas Instruments
- Category:
- FIFOs Memory
- Package:
- 120-LQFP
- Datasheet:
-
SN74ACT3631-15PCB.pdf
- Description:
- IC FIFO SYNC 512X36 120HLQFP
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
SN74ACT3631-15PCB from Texas Instruments is a 512 × 36-bit clocked FIFO memory IC with dual asynchronous ports, supporting up to 67 MHz clock frequency, 11 ns read access time, and programmable almost-full/empty flags synchronized to CLKA and CLKB respectively. It enables high-speed data buffering between microprocessor buses in telecom switching and DSP interface applications.
For engineers reviewing the SN74ACT3631-15PCB datasheet, SN74ACT3631-15PCB pinout, SN74ACT3631-15PCB application, or SN74ACT3631-15PCB equivalent, key selection considerations include its 120-pin thin quad flat (PCB) package, synchronous retransmit capability, mailbox register support, and compatibility with SN74ACT3641/SN74ACT3651 for width expansion.
Technical Context
The SN74ACT3631-15PCB implements a dual-clock, 512-word × 36-bit SRAM-based FIFO with independent CLKA and CLKB domains enabling fully asynchronous operation. Its two-stage synchronized flag logic (IR/AF to CLKA; OR/AE to CLKB) mitigates metastability across clock domains while supporting coincident or free-running clocks.
It integrates mailbox registers (Mail1/Mail2) with dedicated MBA/MBB controls and flag outputs (MBF1/MBF2), plus programmable offset registers for AF/AE flags via parallel load (A8–A0), serial load (FS0/SD + FS1/SEN), or preset values (8 or 64). Retransmit mode uses shadow read pointer and RFM control for repeatable FIR filter coefficient streaming.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Depth × Width | 512 × 36 bits - supports full 36-bit parallel data path buffering with 512-word depth for burst-mode traffic shaping. |
| Max Clock Frequency | 67 MHz - enables real-time data transfer at up to 2.4 Gb/s aggregate throughput (36 bits × 67 MHz). |
| Read Access Time | 11 ns - guarantees deterministic latency for time-critical output-ready assertion and data availability. |
| Flag Synchronization | Two-stage flip-flop sync - IR/AF tied to CLKA edge; OR/AE tied to CLKB edge; eliminates metastability in async clock domain crossing. |
| Operating Temperature | 0°C to 70°C - qualified for commercial-grade embedded systems including industrial controllers and communications infrastructure. |
| Technology Node | 0.8-µm Advanced CMOS - delivers low power consumption while maintaining TTL-compatible input thresholds and 36 mA drive strength. |
| Programmable Offsets | X (AE) and Y (AF) registers - configurable from 1 to 508 words via serial, parallel, or preset loading for precise buffer watermarking. |
Pinout & Package
SN74ACT3631-15PCB is housed in a 120-pin thin quad flat package (TQFP), designated PCB per TI documentation. Pin layout follows standard TI 120-pin TQFP footprint with 0.4 mm pitch and exposed thermal pad.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A35 | Port-A bidirectional data bus | 36-bit parallel I/O for write/read operations on port A; high-impedance when CSA or W/RA high. |
| B0–B35 | Port-B bidirectional data bus | 36-bit parallel I/O for write/read operations on port B; high-impedance when CSB or W/RB low. |
| CLKA, CLKB | Free-running port clocks | Independent continuous clocks; CLKA gates port-A transfers; CLKB gates port-B transfers; may be async or coincident. |
| ENA, ENB | Port master enable inputs | Enable/disable all port-A/B operations; must be high for CLKA/CLKB transitions to trigger reads/writes. |
| CSA, CSB | Port chip select inputs | Active-low enables; disable port data drivers and block clock-triggered transfers when deasserted. |
| W/RA, W/RB | Port write/read direction controls | W/RA high = write; W/RB high = read; defines data flow direction per port on each clock edge. |
| IR, OR, AF, AE | Synchronized status flags | IR/AF synced to CLKA; OR/AE synced to CLKB; indicate FIFO fill level with programmable thresholds. |
| MBA, MBB | Mailbox select inputs | Select mail1/mail2 register instead of FIFO for port-A/B data transfers; enable command/control bypass paths. |
| RST | Asynchronous reset input | Requires four rising edges on both CLKA and CLKB while low; initializes pointers, flags, and mailbox states. |
| RTM, RFM | Retransmit control inputs | RTM initiates retransmit mode; RFM resets read pointer to retransmit start point during active retransmit. |
| FS0/SD, FS1/SEN | Flag offset programming interface | Dual-function pins: configure AF/AE offset loading method (serial/parallel/preset) during RST assertion. |
| VCC, GND | Power supply terminals | Multiple VCC (pins 5, 10, 22, 34, 43, 50, 66, 73, 95, 102, 110, 119) and GND (pins 8, 18, 25, 37, 46, 53, 60, 76, 84, 91, 99, 107, 115) pins ensure stable power delivery and low-noise operation. |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous retransmit mode | Enables repeatable read-out of FIFO contents from user-defined start address using shadow read pointer and RFM control-critical for FIR filtering and coefficient replay. |
| Dual mailbox registers (Mail1/Mail2) | Provide dedicated 36-bit command/control channels between ports with MBF1/MBF2 flags signaling new mail arrival-eliminates polling overhead in inter-processor communication. |
| Programmable almost-full/empty flags | AF/AE thresholds set via serial, parallel, or preset methods (range 1–508 words), allowing precise buffer management for variable-rate data streams. |
| Metastability-hardened flag synchronization | Two-stage synchronizers on IR/AF (to CLKA) and OR/AE (to CLKB) reduce failure probability in asynchronous clock domain crossings per SCZA004 analysis. |
| Pin-to-pin compatibility | Direct replacement for SN74ACT3641 and SN74ACT3651-enables seamless migration or parallel stacking for wider datapaths without PCB redesign. |
Applications
| Telecom Switching Fabric | DSP Interface Buffering |
|---|---|
|
Use Scenario: Buffering packetized voice/data between line cards and switch fabric ASICs operating at different clock domains. IC Role / Device Role / Timing Role: Clocked FIFO providing elastic storage with independent CLKA/CLKB domains to absorb jitter and rate mismatches. Use Value: Eliminates data loss during clock domain crossing; 11 ns access time ensures sub-cycle latency for real-time voice frame alignment. |
Use Scenario: Streaming FIR filter coefficients and sample data between DSP core and external memory or ADC/DAC interfaces. IC Role / Device Role / Timing Role: Dual-port FIFO with retransmit mode acting as coefficient repeater and data pipeline stage. Use Value: Synchronous retransmit allows repeated coefficient reads without host intervention; mailbox registers handle control commands concurrently. |
| Industrial PLC Backplane | Parallel Bus Bridge |
|
Use Scenario: Interfacing legacy 8/16-bit microcontrollers with modern 36-bit fieldbus controllers over shared backplane. IC Role / Device Role / Timing Role: Width-expansible FIFO used in parallel with identical units to match 36-bit data width while preserving timing integrity. Use Value: Pin-compatible expansion enables scalable bandwidth; programmable AF/AE flags prevent overflow under variable scan cycle loads. |
Use Scenario: Bridging mismatched CPU and peripheral buses (e.g., x86 ISA to custom FPGA interface) requiring burst-mode handshaking. IC Role / Device Role / Timing Role: Clocked FIFO with microprocessor interface logic (CSA/CSB, ENA/ENB, W/RA/W/RB) serving as protocol-transparent bridge. Use Value: Input-ready/output-ready flags provide hardware flow control; mailbox registers convey configuration updates without stalling main data path. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar clocked FIFO memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ACT3641-15PCB | Same 512 × 36 architecture and pinout; differs only in flag offset default values and minor timing spec tolerances. | Identical use cases; selected when factory-default AF=64/AE=64 behavior is preferred over SN74ACT3631's AF=8/AE=8 defaults. | Drop-in replacement where preset offset values align with system design assumptions; no layout or firmware changes required. |
| SN74ACT3651-15PCB | Shares same package, pinout, and functional block diagram; differs in internal flag synchronization delay and retransmit initialization sequence. | Used in legacy designs requiring strict compliance with earlier TI FIFO timing margins; less tolerant of aggressive clock skew. | Preferred for backward compatibility in systems originally validated with SN74ACT3651; verify setup/hold timing against current design margins. |
Compared with SN74ACT3631-15PCB, SN74ACT3641-15PCB offers identical performance with different factory-programmed flag offsets, while SN74ACT3651-15PCB provides legacy-tuned timing behavior-both retain full pin and functional compatibility for drop-in substitution or width expansion.
Availability
SN74ACT3631-15PCB is available at Aetrix Electronics and suitable for telecom switching fabric, DSP interface buffering, and industrial PLC backplane applications requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for SN74ACT3631-15PCB 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 decades of heritage in high-reliability interface and memory products.
The SN74ACT3631-15PCB belongs to TI's ACT-family advanced CMOS FIFO portfolio, designed specifically for high-speed, low-latency inter-processor and inter-subsystem data buffering in telecom, industrial automation, and digital signal processing systems.
FAQ
What is the maximum clock frequency supported by the SN74ACT3631-15PCB?
The SN74ACT3631-15PCB supports clock frequencies up to 67 MHz on both CLKA and CLKB inputs. This specification is characterized across the full commercial temperature range (0°C to 70°C) and reflects the device's ability to sustain reliable data transfer at this rate with guaranteed setup/hold timing margins per the SCAS246G datasheet.
How does the SN74ACT3631-15PCB handle asynchronous clock domains between port A and port B?
The SN74ACT3631-15PCB handles asynchronous clock domains using two-stage synchronizers on all status flags: IR and AF are synchronized to CLKA, while OR and AE are synchronized to CLKB. This architecture reduces metastability risk during cross-domain flag sampling, as validated in TI application report SCZA004.
Can the SN74ACT3631-15PCB be used for retransmitting data sequences, and how is it configured?
Yes, the SN74ACT3631-15PCB supports synchronous retransmit mode via RTM and RFM inputs. When RTM is asserted high with OR high, a rising CLKB edge marks the current output register content as the retransmit start point. Subsequent RFM assertions during retransmit mode reset the read pointer to replay that sequence-enabling repeatable FIR coefficient streaming without host CPU involvement.
What are the available methods to program the almost-full and almost-empty flag offsets in the SN74ACT3631-15PCB?
The SN74ACT3631-15PCB supports three AF/AE offset programming methods: (1) preset values (8 or 64) selected via FS1/FS0 during RST assertion; (2) parallel load from port-A data lines A8–A0; or (3) serial load via FS0/SD clocked by CLKA while FS1/SEN is low. All methods allow offset values from 1 to 508 words.
Is the SN74ACT3631-15PCB pin-compatible with other devices in the same family?
Yes, the SN74ACT3631-15PCB is pin-to-pin compatible with SN74ACT3641-15PCB and SN74ACT3651-15PCB. This allows direct substitution or parallel stacking to increase data bus width, provided system-level timing and flag offset requirements are verified per each variant's datasheet specifications.
SN74ACT3631-15PCB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ACT
- Package/Case:
- 120-LQFP
- Packaging:
- Tray
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Size:
- 18K (512 x 36)
- Function:
- Synchronous
- Data Rate:
- 66.7MHz
- Access Time:
- 11ns
- Voltage - Supply:
- 4.5 V ~ 5.5 V
- Current - Supply (Max):
- 400µA
- Bus Directional:
- Bi-Directional
- Expansion Type:
- Depth, Width
- Programmable Flags Support:
- Yes
- Retransmit Capability:
- Yes
- FWFT Support:
- No
- Operating Temperature:
- 0°C ~ 70°C
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 120-HLQFP (14x14)
SN74ACT3631-15PCB FAQ
1.How can I place an order for SN74ACT3631-15PCB through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ACT3631-15PCB 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 SN74ACT3631-15PCB reliable?
The price and inventory of SN74ACT3631-15PCB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ACT3631-15PCB is usually 5 days.
3.What payment methods are accepted for SN74ACT3631-15PCB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ACT3631-15PCB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ACT3631-15PCB?
SN74ACT3631-15PCB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ACT3631-15PCB 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 SN74ACT3631-15PCB?
For technical support, including SN74ACT3631-15PCB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ACT3631-15PCB requirements.
6.How does Aetrix verify that SN74ACT3631-15PCB is sourced from the original manufacturer or authorized distributors?
All SN74ACT3631-15PCB 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 SN74ACT3631-15PCB meets industry standards.
7.What is the process for return or replacement of SN74ACT3631-15PCB?
All SN74ACT3631-15PCB units undergo pre-shipment inspection (PSI). If there is an issue with SN74ACT3631-15PCB, 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 SN74ACT3631-15PCB part is unused and in its original packaging.
Return procedure for SN74ACT3631-15PCB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SN74ACT3631-15PCB Tags
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7201LA15JGI
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7204L12JG
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72V82L15PAG8
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7205L15JGI
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7208L20JG
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72V2105L10PFG
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72V2111L15PFGI
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72V2113L6PFG
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72V36110L6PFG
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SN74ALVC7804-40DL
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7202LA25JGI
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SN74V245-15PAG
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