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Texas Instruments SN74ACT7806-40DLR
- Part No.:
- SN74ACT7806-40DLR
- Manufacturer:
- Texas Instruments
- Category:
- FIFOs Memory
- Package:
- 56-BSSOP (0.295", 7.50mm Width)
- Datasheet:
-
SN74ACT7806-40DLR.pdf
- Description:
- IC FIFO ASYNC 256X18 56SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,749
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Product details
Overview
SN74ACT7806-40DLR from Texas Instruments is a 256 × 18-bit strobed FIFO memory IC with 15 ns access time, 40 MHz maximum clock frequency, and programmable almost-full/almost-empty flags. It operates over 0°C to 70°C, features 3-state outputs, and supports independent load/unload clocks for asynchronous data buffering in high-speed digital systems.
For engineers reviewing the SN74ACT7806-40DLR datasheet, SN74ACT7806-40DLR pinout, SN74ACT7806-40DLR application, or SN74ACT7806-40DLR equivalent, this device serves as a timing-critical first-in, first-out buffer for data rate matching between mismatched clock domains in communications interfaces, video pipelines, and industrial controllers.
Technical Context
The SN74ACT7806-40DLR implements a 256-word deep × 18-bit wide static RAM core with dual-clock strobe control: LDCK triggers write-on-rising-edge, UNCK triggers read-on-rising-edge. Its internal pointer logic maintains full/empty/half-full status independently of clock phase alignment.
Status flag generation is hardware-based and deterministic: FULL and EMPTY are active-low open-drain–compatible outputs; HF asserts high at ≥128 words; AF/AE is programmable via D0–D6 latched on LDCK edges under PEN control, supporting custom depth thresholds (X/Y) from 0 to 127.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Depth × Width | 256 × 18 bits - provides 4,608-bit buffer capacity for parallel word-aligned data streams |
| Max Clock Frequency | 40 MHz - supports sustained data throughput up to 720 MB/s (18 bits × 40 MHz) |
| Access Time | 15 ns - guarantees valid Q-output setup after LDCK↑ or UNCK↑ under 50-pF load |
| Supply Voltage | 4.5 V to 5.5 V - compatible with standard 5-V TTL and CMOS logic rails |
| Operating Temperature | 0°C to 70°C - rated for commercial-grade embedded and industrial control environments |
| Output Drive | 16 mA sink / –8 mA source - drives standard 50-Ω transmission lines or fan-out to ≥10 LSTTL loads |
| Flag Logic Levels | FULL/EMPTY active-low; HF/AF/AE active-high - simplifies direct connection to microcontroller GPIO or FPGA status inputs |
Pinout & Package
Packaged in a 56-pin Shrink Small-Outline Package (SSOP-DL), 300-mil body width, 25-mil center-to-center lead pitch, RoHS-compliant NIPDAU finish, MSL Level-1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (RESET) | Asynchronous reset input | Drives FULL high, EMPTY low, HF low, and clears internal pointers - required at power-up |
| 2–9, 11–12, 14–17 (D0–D17) | Data input bus | 18-bit parallel input port; D0–D6 used to program AF/AE offsets when PEN is low |
| 22 (HF) | Status output | High when FIFO contains ≥128 words - enables coarse-grained flow control without polling |
| 23 (PEN) | Programming enable input | Low during reset enables latching of D0–D6 as X/Y offset values on subsequent LDCK edges |
| 24 (AF/AE) | Programmable status output | High when word count ≤ X or ≥ (256 − Y); default X = Y = 32 if PEN held high |
| 25 (LDCK) | Load clock input | Rising-edge-triggered write strobe; disabled when FULL is low |
| 28 (FULL) | Status output | Active-low full flag - prevents overflow by disabling further writes when asserted |
| 29 (EMPTY) | Status output | Active-low empty flag - prevents underflow by disabling reads when asserted |
| 32 (UNCK) | Unload clock input | Rising-edge-triggered read strobe; disabled when EMPTY is low |
| 33–34, 36–38, 40–43, 45–49, 51, 53–55 (Q0–Q17) | Data output bus | Noninverting 18-bit parallel output; high-impedance when OE is high |
| 56 (OE) | Output enable input | Active-low control for 3-state output drivers - allows bus sharing without external logic |
Key Features
| Feature | Design Value |
|---|---|
| Pin-to-pin compatibility | Direct replacement for SN74ACT7804 and SN74ACT7814 - enables drop-in upgrade path within same footprint |
| Programmable AF/AE thresholds | X and Y offsets configurable from 0 to 127 via D-bus and PEN - supports custom backpressure signaling for variable-rate systems |
| Dual asynchronous clocks | Independent LDCK and UNCK inputs - eliminates need for clock domain crossing logic in FPGA or ASIC designs |
| Hardware status flags | FULL, EMPTY, HF, and AF/AE all generated on-chip - removes requirement for external counter or state machine |
| Low-power Advanced CMOS | ICC ≤ 400 µA typical at 5.5 V - reduces thermal load in dense PCB layouts without sacrificing speed |
Applications
| Video Frame Buffering | Industrial PLC Data Pipeline |
|---|---|
|
Use Scenario: Synchronizing pixel data between camera sensor (72 MHz) and display controller (60 Hz refresh). IC Role / Device Role / Timing Role: Strobed FIFO buffer absorbing bursty sensor output and delivering steady stream to timing-critical display engine. Use Value: Eliminates frame drops by decoupling mismatched clocks; 256-word depth accommodates worst-case line-buffer latency. |
Use Scenario: Isolating fieldbus I/O scan cycles (10 ms) from real-time motion control loop (100 µs). IC Role / Device Role / Timing Role: Asynchronous data bridge between slow serial protocol handler and fast servo update engine. Use Value: Prevents CPU stalls during I/O bursts; programmable AF/AE enables early warning before buffer exhaustion. |
| Network Packet Assembly | Digital Audio Sample Rate Conversion |
|
Use Scenario: Aggregating fragmented Ethernet frames from multiple MAC layers into unified DMA buffer. IC Role / Device Role / Timing Role: High-speed parallel FIFO collecting 18-bit packet headers prior to CRC calculation and forwarding. Use Value: 40 MHz clock support handles 100 Mbps wire-rate traffic; 3-state outputs simplify integration with shared system bus. |
Use Scenario: Bridging SPDIF receiver (44.1 kHz) and DAC subsystem (48 kHz) in professional audio gear. IC Role / Device Role / Timing Role: Elastic buffer compensating for sample clock drift between asynchronous audio domains. Use Value: HF and AF/AE flags drive adaptive clock recovery logic; 15 ns access ensures jitter-free sample delivery. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar FIFO memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ACT7804-40DL | 256 × 9-bit width; half the data bus size; identical timing and flag architecture | Suitable only for 9-bit or narrower data paths; requires two devices for 18-bit operation | Select when system bus width is ≤9 bits or cost-per-bit optimization is critical |
| SN74ACT7814-40DL | 512 × 9-bit width; double depth but same 9-bit interface; shares pinout with SN74ACT7804 | Provides longer buffering for latency-sensitive protocols but lacks native 18-bit interface | Choose when deeper buffering outweighs bus-width mismatch and board space permits dual-device layout |
Compared with SN74ACT7804-40DL and SN74ACT7814-40DL, the SN74ACT7806-40DLR delivers native 18-bit parallel throughput in a single package - reducing PCB trace count, eliminating inter-device skew, and simplifying timing closure for wide-data-path systems.
Availability
SN74ACT7806-40DLR is available at Aetrix Electronics and suitable for video frame buffering, industrial PLC data pipelines, network packet assembly, and digital audio sample rate conversion requiring stable component supply across extended production lifecycles.
Supply support for SN74ACT7806-40DLR 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 SN74ACT7806-40DLR belongs to TI's Widebus™ family of high-speed interface logic, engineered specifically for deterministic, low-latency data buffering in multi-clock-domain digital systems.
FAQ
What is the maximum operating frequency of the SN74ACT7806-40DLR?
The SN74ACT7806-40DLR supports a maximum clock frequency of 40 MHz for both LDCK and UNCK inputs, as confirmed by timing specifications in the SCAS438C datasheet revision April 1998. This rating applies under recommended operating conditions (VCC = 4.5 V to 5.5 V, TA = 0°C to 70°C) with CL = 50 pF.
How does the AF/AE flag programming work on the SN74ACT7806-40DLR?
After RESET assertion, holding PEN low enables programming of AF/AE offset values X and Y using D0–D6 on successive LDCK rising edges. The first LDCK↑ latches X; a second LDCK↑ (with PEN still low) latches Y. Default values (X = Y = 32) apply if PEN remains high. The SN74ACT7806-40DLR implements this behavior per Figure 1 in the datasheet.
Is the SN74ACT7806-40DLR pin-compatible with other members of the ACT78xx family?
Yes, the SN74ACT7806-40DLR is pin-to-pin compatible with SN74ACT7804 and SN74ACT7814 per the datasheet's "Pin-to-Pin Compatible With" statement. All three share the same DL (SSOP-56) package, identical pin functions for control/status signals, and overlapping power/ground pin locations - enabling mechanical and layout reuse.
What is the purpose of the HF (half-full) flag on the SN74ACT7806-40DLR?
The HF flag on the SN74ACT7806-40DLR is a fixed-threshold status output that goes high when the FIFO contains 128 or more words (exactly half of its 256-word capacity). It provides rapid visibility into buffer occupancy without software polling, supporting efficient flow control in real-time systems where mid-level fill detection is sufficient.
Does the SN74ACT7806-40DLR require power-on reset, and what happens if RESET is not asserted?
Yes, the SN74ACT7806-40DLR must be reset upon power-up, as explicitly stated in the datasheet: "The FIFO must be reset upon power up." Without RESET assertion, internal stack pointers remain undefined, FULL/EMPTY/HF flags default to indeterminate states, and data output behavior is unpredictable - potentially causing system lockup or data corruption.
SN74ACT7806-40DLR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ACT
- Package/Case:
- 56-BSSOP (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Size:
- 4.5K (256 x 18)
- Function:
- Asynchronous
- Data Rate:
- 25MHz
- Access Time:
- 20ns
- 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
SN74ACT7806-40DLR FAQ
1.How can I place an order for SN74ACT7806-40DLR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ACT7806-40DLR 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 SN74ACT7806-40DLR reliable?
The price and inventory of SN74ACT7806-40DLR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ACT7806-40DLR is usually 5 days.
3.What payment methods are accepted for SN74ACT7806-40DLR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ACT7806-40DLR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ACT7806-40DLR?
SN74ACT7806-40DLR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ACT7806-40DLR 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 SN74ACT7806-40DLR?
For technical support, including SN74ACT7806-40DLR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ACT7806-40DLR requirements.
6.How does Aetrix verify that SN74ACT7806-40DLR is sourced from the original manufacturer or authorized distributors?
All SN74ACT7806-40DLR 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 SN74ACT7806-40DLR meets industry standards.
7.What is the process for return or replacement of SN74ACT7806-40DLR?
All SN74ACT7806-40DLR units undergo pre-shipment inspection (PSI). If there is an issue with SN74ACT7806-40DLR, 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 SN74ACT7806-40DLR part is unused and in its original packaging.
Return procedure for SN74ACT7806-40DLR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SN74ACT7806-40DLR Tags
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