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Texas Instruments SN74ACT7802-40FN
- Part No.:
- SN74ACT7802-40FN
- Manufacturer:
- Texas Instruments
- Category:
- FIFOs Memory
- Package:
- 68-LCC (J-Lead)
- Datasheet:
-
SN74ACT7802-40FN.pdf
- Description:
- IC FIFO ASYNC 1KX18 35NS 68PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:1,813
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Product details
Overview
SN74ACT7802-40FN from Texas Instruments is a 1024 × 18-bit strobed FIFO memory IC designed for high-speed data buffering between asynchronous clock domains. It delivers 30 ns access time, supports up to 40 MHz data rates, features programmable almost-full/almost-empty flags, and provides 3-state outputs for direct bus interface in industrial and telecom systems.
For engineers reviewing the SN74ACT7802-40FN datasheet, SN74ACT7802-40FN pinout, SN74ACT7802-40FN application, or SN74ACT7802-40FN equivalent, this page details its timing behavior, flag programming logic, load/unload clock independence, status flag truth table, and FN-package terminal mapping for reliable system integration.
Technical Context
The SN74ACT7802-40FN implements a dual-clock, bit-parallel FIFO architecture with independent write (LDCK) and read (UNCK) paths, enabling seamless bridging of mismatched data streams. Its internal 1024-word × 18-bit RAM uses advanced CMOS technology to achieve 20 ns fall-through time and 30 ns access time at 50-pF load.
Status monitoring relies on five dedicated output flags-FULL, EMPTY, HF, AF/AE, and DAF-controlled offset programming-with RESET synchronizing pointer logic and flag initialization. The device operates across 0°C to 70°C with 4.5 V–5.5 V supply and supports cascading only in word-width (not depth), limiting expansion to parallel 18-bit interfaces.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Depth × Width | 1024 words × 18 bits - fixed buffer size supporting burst-mode data alignment without external address management. |
| Max Clock Frequency | 40 MHz - enables real-time streaming at 720 MB/s aggregate throughput (18 bits × 40 MHz). |
| Access Time | 30 ns - guarantees deterministic latency from LDCK/UNCK edge to valid Q-output transition under 50-pF load. |
| Fall-Through Time | 20 ns typical - defines minimum delay from input data arrival to first output availability after reset or empty state. |
| Flag Programmability | AF/AE offset configurable via D0–D8 and DAF pin - allows user-defined thresholds (e.g., 128 or 256 words) for early flow control signaling. |
| Output Drive | –8 mA / +16 mA - sufficient to drive standard TTL/CMOS buses directly without line buffers. |
| Supply Voltage Range | 4.5 V to 5.5 V - compatible with 5-V logic systems while tolerating ±10% rail variation. |
Pinout & Package
SN74ACT7802-40FN is housed in a 68-pin plastic quad flatpack (FN) package with 0.8-mm lead pitch and 20.32 mm × 13.97 mm body dimensions. Pin numbering follows top-view orientation with pin 1 at bottom-left corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| LDCK (Pin 29) | Write clock input | Rising-edge-triggered load clock; writes D0–D17 into FIFO only when FULL = high. |
| UNCK (Pin 5) | Read clock input | Rising-edge-triggered unload clock; reads Q0–Q17 only when EMPTY = low. |
| RESET (Pin 1) | Asynchronous reset | Active-low signal that clears internal pointers, sets FULL/AF/AE high, and forces HF/EMPTY low. |
| OE (Pin 2) | Output enable | Active-low control: disables Q0–Q17 outputs into high-impedance state for bus sharing. |
| AF/AE (Pin 33) | Status flag output | Programmable almost-full/almost-empty indicator; high when FIFO contains ≤X or ≥(1024–X) words. |
| DAF (Pin 27) | Offset configuration | Defines AF/AE threshold: falling edge latches D0–D8 as custom X value; held high selects default X = 256. |
| D0–D17 (Pins 7–15,17,19–26) | Data inputs | 18-bit parallel input port accepting data on LDCK rising edge; no internal latching outside clock event. |
| 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 outputs enabled by OE; retain last-read value until next UNCK edge. |
Key Features
| Feature | Design Value |
|---|---|
| Independent Load/Unload Clocks | Enables true asynchronous operation between source and sink domains without clock domain crossing logic. |
| Programmable AF/AE Offset | Supports dynamic flow control tuning via D0–D8 and DAF pin, eliminating need for external comparator circuits. |
| Five Status Flags | FULL, EMPTY, HF, AF/AE, and DAF provide complete real-time buffer occupancy visibility for hardware-based throttling. |
| 3-State Outputs with High Drive | –8 mA / +16 mA output strength allows direct connection to backplane or multi-drop buses without level-shifting. |
| Fast Fall-Through Timing | 20 ns typical delay from data input to first output appearance simplifies startup synchronization in burst-transfer systems. |
Applications
| Telecom Line Card Buffering | Industrial PLC Data Aggregation |
|---|---|
|
Use Scenario: Buffering variable-rate packetized voice/data between TDM framer and ATM switch fabric. IC Role / Device Role / Timing Role: Strobed FIFO decouples 8 kHz TDM write clock from 622 Mbps SONET read clock while maintaining jitter-free data integrity. Use Value: Eliminates software-based buffering overhead and prevents packet loss during clock skew events using hardware flags (FULL/EMPTY/AF/AE). |
Use Scenario: Consolidating sensor readings from multiple I/O modules into a central controller over RS-485. IC Role / Device Role / Timing Role: Synchronizes bursty analog-to-digital conversion results (18-bit resolution) with slower polling-based master MCU. Use Value: Prevents overrun/underrun during scan cycle transitions using HF and programmable AF/AE to trigger adaptive polling intervals. |
| Test Equipment Pattern Memory | Video Frame Rate Conversion |
|
Use Scenario: Capturing high-speed digital stimulus patterns from pattern generator before analysis by logic analyzer. IC Role / Device Role / Timing Role: Acts as elastic store between 40 MHz pattern clock and 25 MHz analysis engine clock. Use Value: Enables glitch-free capture of 1024 consecutive 18-bit vectors with precise timestamp correlation via LDCK/UNCK edge alignment. |
Use Scenario: Converting 60 Hz progressive video frames to 50 Hz interlaced output for broadcast compatibility. IC Role / Device Role / Timing Role: Temporarily stores pixel rows during frame resampling to absorb timing mismatch between input and output scan clocks. Use Value: Maintains vertical sync stability using HALF-FULL flag to trigger line-doubling or dropping logic without frame tearing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar FIFO memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| IDT7203L15TPG | 1024 × 9-bit depth, 15 ns access, 5 V supply, 28-pin SOIC - half the data width, faster access, smaller package. | Requires two devices in parallel for 18-bit interface; lacks programmable AF/AE and DAF pin. | Choose when board space is constrained and 9-bit granularity suffices; avoid if single-chip 18-bit buffering is required. |
| ON Semiconductor MC100E131FNG | ECL-based 512 × 18-bit FIFO, 3.3 V operation, 4 ns access - higher speed but incompatible voltage/logic family. | Demands ECL-level signal conditioning and power delivery; unsuitable for 5 V TTL/CMOS systems. | Select only for ultra-low-latency ECL designs; not drop-in compatible due to voltage, logic family, and capacity differences. |
Compared with IDT7203L15TPG and MC100E131FNG, SN74ACT7802-40FN uniquely delivers 18-bit-wide single-package buffering at 40 MHz with user-programmable flow-control thresholds - making it optimal for 5 V industrial and telecom systems requiring deterministic, hardware-managed data staging.
Availability
SN74ACT7802-40FN is available at Aetrix Electronics and suitable for telecom line cards, industrial PLCs, automated test equipment, and broadcast video rate converters requiring stable component supply across extended production lifecycles.
Supply support for SN74ACT7802-40FN 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 founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The SN74ACT7802-40FN belongs to TI's Widebus™ family of high-speed interface ICs, engineered specifically for robust, low-jitter data buffering in asynchronous digital systems operating at 5 V.
FAQ
What is the maximum data rate supported by the SN74ACT7802-40FN?
The SN74ACT7802-40FN supports data rates up to 40 MHz, corresponding to a maximum throughput of 720 MB/s (18 bits × 40 MHz). This rating is validated under recommended operating conditions (VCC = 4.5 V to 5.5 V, TA = 0°C to 70°C) with CL = 50 pF load, and aligns with its –40 speed grade designation in the SN74ACT7802 family.
How does the AF/AE flag operate in the SN74ACT7802-40FN?
In the SN74ACT7802-40FN, the AF/AE flag goes high when the FIFO contains X or fewer words (almost empty) or (1024 – X) or more words (almost full), where X is either the default 256 or a user-defined value programmed via D0–D8 and the DAF pin. After reset, AF/AE defaults high regardless of occupancy.
Can the SN74ACT7802-40FN be used in cascaded configurations for increased depth?
No, the SN74ACT7802-40FN does not support cascading in word-depth direction. It can only be expanded in word-width (e.g., two devices for 1024 × 36-bit operation), as confirmed in the functional description and Figure 5 of the datasheet. Depth expansion would require external control logic and is not architecturally supported.
What is the purpose of the DAF pin on the SN74ACT7802-40FN?
The DAF (Define Almost-Full) pin on the SN74ACT7802-40FN controls AF/AE flag offset programming: a high-to-low transition latches the binary value on D0–D8 as the custom AF/AE threshold X; holding DAF high during reset selects the default X = 256. This eliminates need for external configuration registers.
Does the SN74ACT7802-40FN require power-on reset?
Yes, the SN74ACT7802-40FN must be reset upon power-up. The datasheet explicitly states "The FIFO must be reset upon power up" to initialize internal stack pointers and set flag states (FULL/AF/AE high, HF/EMPTY low); failure to do so results in undefined flag behavior and potential data corruption.
SN74ACT7802-40FN 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:
- Asynchronous
- Data Rate:
- 25MHz
- Access Time:
- 35ns
- Voltage - Supply:
- 4.5 V ~ 5.5 V
- Current - Supply (Max):
- 400µA
- Bus Directional:
- Uni-Directional
- Expansion Type:
- 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)
SN74ACT7802-40FN FAQ
1.How can I place an order for SN74ACT7802-40FN through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ACT7802-40FN 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 SN74ACT7802-40FN reliable?
The price and inventory of SN74ACT7802-40FN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ACT7802-40FN is usually 5 days.
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SN74ACT7802-40FN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ACT7802-40FN 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 SN74ACT7802-40FN?
For technical support, including SN74ACT7802-40FN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ACT7802-40FN requirements.
6.How does Aetrix verify that SN74ACT7802-40FN is sourced from the original manufacturer or authorized distributors?
All SN74ACT7802-40FN 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 SN74ACT7802-40FN meets industry standards.
7.What is the process for return or replacement of SN74ACT7802-40FN?
All SN74ACT7802-40FN units undergo pre-shipment inspection (PSI). If there is an issue with SN74ACT7802-40FN, 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 SN74ACT7802-40FN part is unused and in its original packaging.
Return procedure for SN74ACT7802-40FN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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