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Texas Instruments SN74ABT7820-15PN
- Part No.:
- SN74ABT7820-15PN
- Manufacturer:
- Texas Instruments
- Category:
- FIFOs Memory
- Package:
- 80-LQFP
- Datasheet:
-
SN74ABT7820-15PN.pdf
- Description:
- IC FIFO ASYNC 512X18X2 80LQFP
- Quantity:
- Payment:
- Shipping:
Inventory:9,124
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Product details
Overview
SN74ABT7820-15PN from Texas Instruments is a strobed bidirectional first-in, first-out (FIFO) memory IC with two independent 512 × 18-bit FIFO buffers operating in opposite directions, supporting up to 67 MHz clock rates, 12 ns access time at 50-pF load, and programmable almost-full/almost-empty flags. It serves as a high-speed data flow controller in bus arbitration and protocol bridging applications between asynchronous subsystems.
For engineers reviewing the SN74ABT7820-15PN datasheet, SN74ABT7820-15PN pinout, SN74ABT7820-15PN application, or SN74ABT7820-15PN equivalent, key selection considerations include dual-FIFO depth and directionality, strobe-synchronized read/write control, programmable flag offsets, and compatibility with 5-V TTL/CMOS logic interfaces in high-throughput digital systems.
Technical Context
The SN74ABT7820-15PN implements two physically separate 512-word × 18-bit FIFOs-FIFO A and FIFO B-with independent load clocks (LDCKA/LDCKB), unload clocks (UNCKA/UNCKB), and reset controls (RSTA/RSTB). Each FIFO supports real-time bypass via SAB/SBA select inputs and transceiver isolation via GAB/GBA enables.
Flag logic includes EMPTYA/EMPTYB, FULLA/FULLB, HFA/HFB, and AF/AEA/AF/AEB with programmable depth offsets (X/Y) latched from A0–A7/B0–B7 during initialization. All timing parameters-including 12 ns access time and 67 MHz max clock frequency-are specified under 5-V supply and 50-pF load conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| FIFO Depth × Width × Count | 512 × 18 × 2 - Dual independent buffers enable simultaneous bidirectional data staging without shared memory contention. |
| Max Clock Frequency | 67 MHz - Supports high-speed data transfer in PCI, VME, or custom parallel bus systems requiring sub-15-ns cycle times. |
| Access Time | 12 ns @ 50-pF load - Enables reliable operation with fast TTL/ABT logic families and tight setup/hold timing margins. |
| Supply Voltage Range | 4.5 V to 5.5 V - Compatible with standard 5-V digital systems; not 3.3-V tolerant. |
| Operating Temperature | 0°C to 70°C - Rated for commercial-grade embedded and industrial control environments. |
| Programmable Flag Offsets | X/Y = 0–255 - Allows fine-grained buffer level monitoring for adaptive flow control in packetized or burst-mode protocols. |
| Output Drive Strength | IOL = 24 mA / IOH = –12 mA - Sufficient to drive 50-pF loads and multiple TTL inputs without external buffering. |
Pinout & Package
SN74ABT7820-15PN uses an 80-pin Thin Quad Flat Package (PN), measuring 12 mm × 12 mm × 1.4 mm, with 0.5-mm lead pitch and exposed thermal pad (not electrically connected). Pin numbering follows standard counter-clockwise top-view convention starting from pin 1 (RSTA) at top-left corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RSTA, RSTB | FIFO reset inputs | Active-low asynchronous resets that force EMPTY low, FULL high, and AF/AE high-critical for deterministic startup and error recovery. |
| LDCKA, LDCKB | FIFO write clocks | Low-to-high transitions write data into respective FIFOs only when FULL flag is high-prevents overflow without external handshaking. |
| UNCKA, UNCKB | FIFO read clocks | Low-to-high transitions read data only when EMPTY flag is high-ensures valid output and avoids underflow glitches. |
| A0–A17, B0–B17 | Bidirectional data ports | 18-bit parallel I/O paths supporting real-time bus pass-through or FIFO-stored data routing based on SAB/SBA control. |
| SAB, SBA | Bus select inputs | Determine whether port outputs reflect live bus data (low) or FIFO contents (high)-enables seamless mode switching without glitching. |
| GAB, GBA | Output enables | Control high-impedance state of B-port and A-port drivers respectively-essential for bus sharing and multi-drop configurations. |
| AF/AEA, AF/AEB | Programmable status flags | Open-drain outputs indicating FIFO occupancy within user-defined almost-empty (X) or almost-full (512−Y) thresholds. |
| EMPTYA, FULLA, HFA | Fixed-function flags | Dedicated outputs for empty (low-active), full (low-active), and half-full (high when ≥256 words) states-simplify interrupt and DMA trigger logic. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent FIFO architecture | Enables concurrent bidirectional data buffering-eliminates need for external arbitration logic in bridge or interface applications. |
| Strobed synchronous read/write control | LDCK/UNCK edge-triggered operation ensures deterministic timing alignment with system clocks and eliminates metastability risks. |
| Programmable almost-full/almost-empty offsets | Allows dynamic tuning of flow-control thresholds via A0–A7/B0–B7 pins-supports variable packet sizes and burst-length adaptation. |
| Real-time bypass + FIFO storage modes | SAB/SBA inputs select between direct bus coupling and buffered transfer-reduces latency when FIFO is empty and maintains throughput during bursts. |
| Advanced BiCMOS process | Delivers 67 MHz speed with TTL-compatible voltage levels and low power consumption (ICC ≈ 15–95 mA depending on activity). |
Applications
| PCI-to-ISA Bridge Buffering | VMEbus Data Rate Matching |
|---|---|
Use Scenario: Bridges legacy ISA peripherals to modern PCI host controllers with mismatched clock domains and burst lengths. IC Role / Device Role / Timing Role: SN74ABT7820-15PN acts as a dual-channel, strobe-synchronized FIFO buffer-absorbing PCI burst writes into FIFO A while feeding ISA-aligned reads from FIFO B. Use Value: Eliminates wait-state insertion and guarantees lossless data transfer across 33 MHz PCI and 8 MHz ISA timing boundaries. |
Use Scenario: Interfaces high-speed VMEbus master modules with slower VME slave devices requiring precise data pacing. IC Role / Device Role / Timing Role: SN74ABT7820-15PN provides independent FIFO A (VME master → slave) and FIFO B (slave → master) paths with programmable AF flags for adaptive DMA triggering. Use Value: Maintains full VMEbus bandwidth while enabling slave-side flow control without stalling the entire backplane. |
| Protocol Translation Interface | Digital Signal Processor (DSP) Co-Processor Link |
Use Scenario: Translates between UART-based command streams and parallel memory-mapped register interfaces in embedded controllers. IC Role / Device Role / Timing Role: SN74ABT7820-15PN decouples UART RX/TX framing (asynchronous) from CPU register access (synchronous), using SAB/SBA to switch between real-time and buffered data paths. Use Value: Prevents UART overrun during CPU register writes and enables zero-copy command queuing for deterministic response. |
Use Scenario: Connects a DSP running at 50+ MHz to a microcontroller operating at 10–20 MHz in audio or motor control systems. IC Role / Device Role / Timing Role: SN74ABT7820-15PN buffers DSP-generated sample blocks in FIFO A and feeds processed results to MCU via FIFO B-both synchronized to local clocks. Use Value: Enables continuous DSP processing without CPU polling, reducing jitter and improving real-time determinism in closed-loop systems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-FIFO buffering applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| IDT7205L15TPG | Single 512 × 9 FIFO; requires two devices for 18-bit width; 15 ns access; 5-V only; no programmable AF offsets. | Lacks integrated dual-directional control and real-time bypass logic-requires external glue logic for equivalent functionality. | Choose when cost-per-bit is prioritized over integration and board space; verify external logic fits timing budget. |
| SN74ACT7820-15PN | Same pinout and function but ACT-family-lower drive (IOL = 24 mA vs ABT's 48 mA), higher noise immunity, identical 67 MHz rating. | Compatible in same PCB layout but may require signal integrity review due to faster edge rates and reduced noise margin. | Prefer for mixed-signal environments where EMI sensitivity is critical; confirm load capacitance remains ≤50 pF. |
Compared with IDT7205L15TPG and SN74ACT7820-15PN, the SN74ABT7820-15PN delivers superior integration via dual 18-bit FIFOs, real-time bypass, and programmable flag thresholds-all in one 80-pin package-reducing component count and simplifying timing-critical designs.
Availability
SN74ABT7820-15PN is available at Aetrix Electronics and suitable for PCI bridging, VMEbus interfacing, protocol translation, and DSP co-processor linking requiring stable component supply across extended production lifecycles.
Supply support for SN74ABT7820-15PN 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 experience in high-speed interface and memory products.
The SN74ABT7820-15PN belongs to TI's Widebus™ family of advanced BiCMOS bus-interface devices, designed specifically for high-bandwidth, low-latency data buffering and protocol bridging in industrial, communications, and computing systems.
FAQ
What is the maximum supported clock frequency for SN74ABT7820-15PN?
The SN74ABT7820-15PN supports a maximum clock frequency of 67 MHz under recommended operating conditions (VCC = 4.5 V to 5.5 V, TA = 0°C to 70°C, CL = 50 pF). This rating applies to both LDCKA/LDCKB and UNCKA/UNCKB inputs and is validated by TI's switching characteristics table in the SCAS206D datasheet.
Does SN74ABT7820-15PN support 3.3-V logic interfaces?
No, SN74ABT7820-15PN is a 5-V-only device with VIH(min) = 2.0 V and VIL(max) = 0.8 V-designed for TTL/ABT-level compatibility. It does not tolerate 3.3-V I/O directly; level-shifting circuitry is required for interfacing with 3.3-V systems.
How are the almost-full/almost-empty flag offsets programmed on SN74ABT7820-15PN?
Offsets for AF/AEA and AF/AEB are programmed after reset: hold PENA low during the first LDCKA↑ to latch A0–A7 as X (almost-empty), then during the second LDCKA↑ to latch Y (almost-full); PENB operates identically for B-side. Default values (X = Y = 128) apply if PENA/PENB remain high.
Can SN74ABT7820-15PN operate with asynchronous clocks on FIFO A and FIFO B?
Yes-SN74ABT7820-15PN supports fully independent clock domains: LDCKA/UNCKA and LDCKB/UNCKB may run at different frequencies and phases, with no synchronization requirement between them. This enables true asynchronous data rate matching between disparate subsystems.
What package type does SN74ABT7820-15PN use, and is it RoHS-compliant?
SN74ABT7820-15PN uses an 80-pin Thin Quad Flat Package (PN) with 0.5-mm pitch. Per TI's product change notices, this PN variant is lead-free and RoHS-compliant, meeting JEDEC J-STD-020 moisture sensitivity level 3 requirements.
SN74ABT7820-15PN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ABT
- Package/Case:
- 80-LQFP
- Packaging:
- Tray
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Size:
- 18K (512 x 18 x 2)
- Function:
- Asynchronous
- Data Rate:
- 67MHz
- Access Time:
- 12ns
- Voltage - Supply:
- 4.5 V ~ 5.5 V
- Current - Supply (Max):
- 95mA
- Bus Directional:
- Bi-Directional
- Expansion Type:
- -
- 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)
SN74ABT7820-15PN FAQ
1.How can I place an order for SN74ABT7820-15PN through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ABT7820-15PN 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 SN74ABT7820-15PN reliable?
The price and inventory of SN74ABT7820-15PN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ABT7820-15PN is usually 5 days.
3.What payment methods are accepted for SN74ABT7820-15PN?
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4.How is shipping managed for SN74ABT7820-15PN?
SN74ABT7820-15PN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ABT7820-15PN 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 SN74ABT7820-15PN?
For technical support, including SN74ABT7820-15PN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ABT7820-15PN requirements.
6.How does Aetrix verify that SN74ABT7820-15PN is sourced from the original manufacturer or authorized distributors?
All SN74ABT7820-15PN 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 SN74ABT7820-15PN meets industry standards.
7.What is the process for return or replacement of SN74ABT7820-15PN?
All SN74ABT7820-15PN units undergo pre-shipment inspection (PSI). If there is an issue with SN74ABT7820-15PN, 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 SN74ABT7820-15PN part is unused and in its original packaging.
Return procedure for SN74ABT7820-15PN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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