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Texas Instruments SN74ACT7803-20DL
- Part No.:
- SN74ACT7803-20DL
- Manufacturer:
- Texas Instruments
- Category:
- FIFOs Memory
- Package:
- 56-BSSOP (0.295", 7.50mm Width)
- Datasheet:
-
SN74ACT7803-20DL.pdf
- Description:
- IC FIFO SYNC 512X18 13NS 56SSOP
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
SN74ACT7803-20DL from Texas Instruments is a 512 × 18-bit clocked FIFO memory IC designed for asynchronous datapath buffering in high-speed digital systems. It features independent free-running read/write clocks (up to 50 MHz), 12 ns access time with 50-pF load, bidirectional configuration capability, and programmable almost-full/almost-empty flags. It is used in data bridging between mismatched clock domains in telecom interface modules.
For engineers reviewing the SN74ACT7803-20DL datasheet, SN74ACT7803-20DL pinout, SN74ACT7803-20DL application, or SN74ACT7803-20DL equivalent, key selection considerations include its 56-pin SSOP (DL) package, synchronous flag behavior (IR synchronized to WRTCLK, OR to RDCLK), reset timing requirements (four rising edges on both clocks), and compatibility with 5-V TTL-level signaling in industrial control backplanes.
Technical Context
The SN74ACT7803-20DL implements a dual-clock FIFO architecture with separate synchronous write and read pointer logic, status-flag generation circuitry (HF, AF/AE, IR, OR), and output-enable-controlled 3-state outputs. Its internal 512 × 18 RAM block supports concurrent read/write operations only when clocks are asynchronous or coincident - no handshake protocol required.
Flag synchronization is strictly clock-domain isolated: IR latches on WRTCLK rising edge, OR on RDCLK rising edge, and AF/AE/ HF derived from internal pointer comparisons with programmable depth offsets. The PEN input enables one-time programming of X/Y offset values (default 64) before first write, disabling writes during configuration.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Depth × Width | 512 words × 18 bits - provides 9,216-bit buffer capacity for burst-mode data alignment across clock domains. |
| Max Clock Frequency | 50 MHz - supports 20-ns minimum clock period for RDCLK/WRTCLK, enabling real-time streaming in serial link interfaces. |
| Access Time | 12 ns (CL = 50 pF) - guarantees deterministic latency from clock edge to valid Q-output, critical for timing-critical FIFO handshaking. |
| Supply Voltage Range | 4.5 V to 5.5 V - compatible with standard 5-V TTL logic families and industrial power rails without level translation. |
| Input/Output Logic Family | Advanced CMOS (ACT) - delivers TTL-compatible input thresholds (VIH = 2 V, VIL = 0.8 V) and 16-mA sink capability on Q outputs. |
| Operating Temperature | 0°C to 70°C - rated for commercial/industrial ambient environments in embedded communications equipment. |
| Package | 56-pin Shrink Small-Outline Package (SSOP-DL, 300-mil width) - surface-mount footprint with 25-mil pin pitch, suitable for high-density PCB layouts. |
Pinout & Package
SN74ACT7803-20DL is housed in a 56-pin Shrink Small-Outline Package (SSOP-DL), 300-mil body width, 25-mil center-to-center pin spacing, RoHS-compliant NiPdAu lead finish, MSL Level-1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (RESET) | Asynchronous reset input | Must be held low while four rising edges occur on both WRTCLK and RDCLK to initialize flags and clear memory pointers. |
| 25 (WRTCLK) | Write clock input | Rising-edge-triggered; synchronizes write enable, input-ready flag (IR), and data capture into FIFO memory. |
| 26–27 (WRTEN2, WRTEN1) | Write enable inputs | Active-low/high pair: write occurs only when WRTEN1 = high, WRTEN2 = low, and IR = high. |
| 2–9, 11–12, 14–21 (D0–D17) | Data input bus | 18-bit parallel input port; D0–D7 also serve as AF/AE offset programming latch inputs when PEN is low. |
| 22 (HF) | Half-full flag output | High when ≥256 words stored; used for coarse flow control in pipeline management. |
| 23 (PEN) | Program enable input | Latches D0–D7 as AF/AE offset values on next WRTCLK rising edge; disables writes during programming. |
| 24 (AF/AE) | Programmable status flag | High when FIFO contains ≤X words (almost-empty) or ≥(512−Y) words (almost-full); defaults to X=Y=64. |
| 28 (IR) | Input-ready flag output | Synchronized to WRTCLK rising edge; low indicates full FIFO and blocks further writes. |
| 30, 56 (OE1, OE2) | Output enable inputs | Both must be low (with RDEN) to enable Q0–Q17 outputs; any high forces high-impedance state. |
| 31 (RDEN) | Read enable input | Low-active; enables read operation when OE1/OE2 are low and OR is high. |
| 32 (RDCLK) | Read clock input | Rising-edge-triggered; advances read pointer and updates OR flag and Q outputs. |
| 29 (OR) | Output-ready flag output | Synchronized to RDCLK rising edge; high indicates valid data present on Q0–Q17 outputs. |
| 33–34, 36–38, 40–43, 45–49, 51, 53–55 (Q0–Q17) | Data output bus | 18-bit parallel output port; first written word appears on Q outputs after third RDCLK edge following initial write. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional data buffering | Two SN74ACT7803-20DL devices can be interconnected without external logic to support full-duplex data flow between clock domains. |
| Programmable AF/AE thresholds | Allows custom almost-full/almost-empty trigger points (X/Y = 0–255) via D0–D7 and PEN, enabling adaptive flow control in variable-bandwidth links. |
| Independent clock domain synchronization | IR and OR flags are each synchronized to their respective clock (WRTCLK/RDCLK), eliminating metastability risk in cross-domain status signaling. |
| Fast 12-ns access with simultaneous switching | All 18 Q outputs switch within 12 ns (CL = 50 pF), supporting high-throughput burst transfers without skew-induced timing violations. |
| Multiple VCC/GND pins + OEC™ | Distributed power/ground pins and Texas Instruments' Output Edge Control dampen simultaneous switching noise, improving signal integrity in dense layouts. |
Applications
| Telecom Line Interface Cards | Industrial PLC Backplane Bridges |
|---|---|
Use Scenario: Buffering T1/E1 framing data between line-side PHY (2.048 MHz) and system-side processor (66 MHz). IC Role / Device Role / Timing Role: Clock-domain decoupling FIFO that absorbs jitter and rate mismatches while maintaining frame alignment. Use Value: Eliminates need for complex handshake logic; 50-MHz RDCLK supports processor-side burst reads without stalling the line interface. |
Use Scenario: Interfacing Modbus RTU slave peripherals (9.6 kbps) to a 50-MHz ARM-based controller in factory automation. IC Role / Device Role / Timing Role: Asynchronous data staging element isolating slow serial peripherals from high-speed CPU bus cycles. Use Value: Prevents CPU polling overhead; HF and AF/AE flags enable efficient DMA-triggered transfers without interrupt latency. |
| Network Packet Assembler/Disassembler | Test Equipment Data Capture Buffers |
Use Scenario: Aggregating 10/100BASE-TX MAC-layer frames into jumbo packets for Gigabit Ethernet uplink. IC Role / Device Role / Timing Role: Elastic store managing variable-length packet ingress under bursty traffic conditions. Use Value: Programmable AF/AE allows dynamic threshold tuning per traffic profile; 512-word depth accommodates worst-case burst accumulation. |
Use Scenario: Capturing high-speed digital stimulus-response waveforms (e.g., 50-MHz pattern generator output) for offline analysis. IC Role / Device Role / Timing Role: Real-time acquisition buffer synchronizing sampling clock (WRTCLK) with analysis host clock (RDCLK). Use Value: 12-ns access time ensures minimal latency between capture and host read; OR flag provides precise ready indication for DMA engine. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar FIFO memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ACT7805-20DL | Pin-to-pin compatible 1,024 × 9-bit FIFO; same timing, package, and flag architecture but half-width, double-depth configuration. | Better suited for narrow-bus, deep-buffer applications (e.g., video line buffers) where 18-bit width is unnecessary. | Select SN74ACT7805-20DL if system data path is 9-bit or requires >512-word depth at lower pin count. |
| SN74ACT7813-20DL | Pin-to-pin compatible 256 × 18-bit FIFO; identical interface and flag behavior but reduced depth and faster 10-ns access time. | Ideal for latency-sensitive, shallow-buffer roles (e.g., real-time audio sample alignment) where 512-word depth is excessive. | Choose SN74ACT7813-20DL when minimizing propagation delay (<10 ns) and reducing memory footprint are prioritized over storage capacity. |
Compared with SN74ACT7805-20DL and SN74ACT7813-20DL, the SN74ACT7803-20DL uniquely balances 18-bit width, 512-word depth, and 12-ns access-making it optimal for medium-depth, wide-data-path bridging where neither extreme depth nor minimal latency dominates design constraints.
Availability
SN74ACT7803-20DL is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLC backplanes, and test equipment requiring stable component supply with long-term lifecycle assurance.
Supply support for SN74ACT7803-20DL 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 industrial and communications ICs.
The SN74ACT7803-20DL belongs to TI's Widebus™ family of advanced CMOS FIFOs, engineered specifically for robust asynchronous data buffering in mixed-clock-domain systems across telecom, industrial, and instrumentation markets.
FAQ
What is the maximum supported clock frequency for SN74ACT7803-20DL?
The SN74ACT7803-20DL supports up to 50 MHz for both RDCLK and WRTCLK, corresponding to a 20-ns minimum clock period. This rating is specified in the timing requirements table for the -20 speed grade and assumes proper termination and 50-pF load conditions. Exceeding this frequency may violate setup/hold timing margins and cause data corruption.
How does the reset sequence work on SN74ACT7803-20DL?
The SN74ACT7803-20DL requires an asynchronous active-low RESET signal asserted while at least four rising edges occur on both WRTCLK and RDCLK. This clears internal pointers and initializes IR, OR, and HF flags low and AF/AE high. The FIFO must be reset at power-up; failure to do so results in undefined flag states and potential read/write errors.
Can SN74ACT7803-20DL be used for bidirectional data flow without external logic?
Yes - two SN74ACT7803-20DL devices can be configured for true bidirectional buffering by cross-connecting D/Q buses and swapping WRTCLK/RDCLK assignments, as shown in Figure 9 of the datasheet. No additional gates or controllers are needed, preserving PCB area and signal integrity in full-duplex interfaces like JTAG boundary-scan chains.
What is the function of the PEN pin on SN74ACT7803-20DL?
The PEN (Program Enable) pin on SN74ACT7803-20DL controls loading of custom AF/AE offset values. When PEN is low during a WRTCLK rising edge, the binary value on D0–D7 is latched as the almost-empty (X) and/or almost-full (Y) threshold. Writes are disabled during programming, and PEN must remain high to retain default X=Y=64.
Is SN74ACT7803-20DL compatible with 3.3-V systems?
No - SN74ACT7803-20DL is a 5-V-only device with absolute maximum VCC of 7 V and recommended operating range of 4.5 V to 5.5 V. Its VIH (2 V) and VIL (0.8 V) thresholds are TTL-compatible but not 3.3-V logic-safe. Interfacing with 3.3-V systems requires level-shifting circuitry or voltage translation ICs to prevent damage or unreliable operation.
SN74ACT7803-20DL Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ACT
- Package/Case:
- 56-BSSOP (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Size:
- 9K (512 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:
- Width
- Programmable Flags Support:
- Yes
- Retransmit Capability:
- No
- FWFT Support:
- No
- Operating Temperature:
- 0°C ~ 70°C
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 56-SSOP
SN74ACT7803-20DL FAQ
1.How can I place an order for SN74ACT7803-20DL through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ACT7803-20DL 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 SN74ACT7803-20DL reliable?
The price and inventory of SN74ACT7803-20DL are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ACT7803-20DL is usually 5 days.
3.What payment methods are accepted for SN74ACT7803-20DL?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ACT7803-20DL transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ACT7803-20DL?
SN74ACT7803-20DL orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ACT7803-20DL 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 SN74ACT7803-20DL?
For technical support, including SN74ACT7803-20DL datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ACT7803-20DL requirements.
6.How does Aetrix verify that SN74ACT7803-20DL is sourced from the original manufacturer or authorized distributors?
All SN74ACT7803-20DL 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 SN74ACT7803-20DL meets industry standards.
7.What is the process for return or replacement of SN74ACT7803-20DL?
All SN74ACT7803-20DL units undergo pre-shipment inspection (PSI). If there is an issue with SN74ACT7803-20DL, 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 SN74ACT7803-20DL part is unused and in its original packaging.
Return procedure for SN74ACT7803-20DL:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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