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Texas Instruments SN74ABT7820-20PH
- Part No.:
- SN74ABT7820-20PH
- Manufacturer:
- Texas Instruments
- Category:
- FIFOs Memory
- Package:
- 80-BQFP
- Datasheet:
-
SN74ABT7820-20PH.pdf
- Description:
- IC FIFO ASYNC 512X18X2 80QFP
- Quantity:
- Payment:
- Shipping:
Inventory:668
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Product details
Overview
SN74ABT7820-20PH 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. It supports 67 MHz clock rates, delivers 12 ns access time at 50-pF load, and features programmable almost-full/almost-empty flags for precise buffer management in high-speed data bridging applications.
For engineers reviewing the SN74ABT7820-20PH datasheet, SN74ABT7820-20PH pinout, SN74ABT7820-20PH application, or SN74ABT7820-20PH equivalent, this device serves as a dual-channel asynchronous FIFO for real-time bus arbitration, protocol translation, and burst-mode data buffering between mismatched clock domains in telecom and industrial control systems.
Technical Context
The SN74ABT7820-20PH integrates two fully independent 512-word × 18-bit FIFOs with separate load/unload clocks (LDCKA/UNCKA and LDCKB/UNCKB), reset controls (RSTA/RSTB), and programmable flag offsets. Each FIFO supports bit-parallel data transfer with dedicated empty/full/half-full/AF-AE flags and configurable depth thresholds via PENA/PENB latching of A0–A7/B0–B7.
Its bus-transceiver architecture enables eight fundamental bus-management modes via SAB/SBA select and GAB/GBA output-enable logic - allowing real-time or stored data routing between Port-A and Port-B without decoding glitches. All timing parameters are specified for VCC = 4.5–5.5 V and TA = 0°C to 70°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Depth × Width × Channels | 512 × 18 × 2 - Dual independent FIFOs, each storing up to 512 words of 18-bit parallel data. |
| Max Clock Frequency | 67 MHz - Enables high-throughput data streaming in synchronous interfaces like PCI or custom backplanes. |
| Access Time | 12 ns @ 50-pF load - Guarantees sub-15 ns latency for read/write operations under standard loading conditions. |
| Supply Voltage Range | 4.5 V to 5.5 V - Compatible with standard 5-V TTL/CMOS logic families and industrial power rails. |
| Operating Temperature | 0°C to 70°C - Rated for commercial and industrial ambient environments without derating. |
| Flag Programmability | AF/AEA & AF/AEB offset values settable via A0–A7/B0–B7 - Allows dynamic tuning of almost-full/almost-empty thresholds (X/Y = 0–255). |
| Output Drive Strength | IOL = 24 mA / IOH = –12 mA - Sustains robust signal integrity driving multiple TTL loads or 50-Ω transmission lines. |
Pinout & Package
SN74ABT7820-20PH uses an 80-pin plastic quad flat package (PH), measuring 24 mm × 24 mm with 0.65 mm lead pitch. The package supports surface-mount assembly and thermal dissipation up to 76°C/W (θJA).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A17 | Port-A bidirectional data bus | 18-bit parallel I/O path for side A; used for data input, output, or AF/AEA offset programming. |
| B0–B17 | Port-B bidirectional data bus | 18-bit parallel I/O path for side B; used for data input, output, or AF/AEB offset programming. |
| LDCKA / LDCKB | FIFO A/B load clock input | Low-to-high edge writes data into respective FIFO; gated by FULLA/FULLB status. |
| UNCKA / UNCKB | FIFO A/B unload clock input | Low-to-high edge reads data from respective FIFO; gated by EMPTYA/EMPTYB status. |
| RSTA / RSTB | FIFO A/B reset input | Active-low asynchronous reset forces EMPTYx low, FULLx high, HFx low, AF/AEx high. |
| PENA / PENB | FIFO A/B program enable | Enables latching of A0–A7/B0–B7 as AF/AEA/AF/AEB offset values during reset initialization. |
| SAB / SBA | Bus select control | Configures real-time vs. FIFO-sourced data routing between Port-A and Port-B per Table 1. |
| GAB / GBA | Port-B/Port-A output enable | High enables transceiver outputs; low places port pins in high-impedance state for bus sharing. |
| AF/AEA / AF/AEB | Programmable almost-full/almost-empty flag | Open-drain output active high when FIFO contains ≤X or ≥(512−Y) words; X/Y default = 128. |
| EMPTYA / EMPTYB | FIFO empty status flag | Active-high indicates non-empty FIFO; low only when FIFO is completely empty. |
| FULLA / FULLB | FIFO full status flag | Active-high indicates non-full FIFO; low only when FIFO is completely full. |
| HFA / HFB | Half-full status flag | Active-high when FIFO contains ≥256 words; provides coarse buffer-level monitoring. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent FIFO architecture | Enables simultaneous bidirectional data flow between two buses without shared clock or control constraints. |
| Programmable AF/AE flag thresholds | Allows runtime-tunable buffer watermarking (X/Y = 0–255) to match system-specific latency and flow-control requirements. |
| Eight-mode bus management | Eliminates multiplexer glitches via synchronized SAB/SBA/GAB/GBA control, supporting real-time bypass and FIFO buffering in any combination. |
| Fast 12 ns access with 67 MHz support | Meets timing budgets for high-speed interconnects including legacy PCI, VME, and proprietary backplane protocols. |
| Asynchronous read/write clocks | Permits seamless data rate translation between independent clock domains (e.g., 33 MHz ↔ 66 MHz). |
Applications
| Telecom Line Card Buffering | Industrial PLC Data Aggregation |
|---|---|
Use Scenario: Buffering bursty TDM traffic between framer and DSP on a line card with mismatched clock domains. IC Role / Device Role / Timing Role: Dual FIFO acts as elastic store for jitter absorption and clock domain crossing between E1/T1 interface and internal processing core. Use Value: Eliminates packet loss during clock skew events; programmable AF/AEA flags trigger DMA requests at optimal fill levels (e.g., X=64, Y=448) to minimize latency and maximize throughput. |
Use Scenario: Consolidating sensor inputs from multiple RS-485 fieldbus nodes into a central controller with variable polling intervals. IC Role / Device Role / Timing Role: SN74ABT7820-20PH serves as deterministic data staging buffer, decoupling slow polling cycles from fast sensor update rates. Use Value: Prevents overrun during burst reads; half-full (HFA/HFB) and empty flags enable precise interrupt-driven data retrieval without polling overhead. |
| Legacy Bus Protocol Translation | Test Equipment Data Capture |
Use Scenario: Bridging ISA-bus peripherals to modern microcontroller-based host systems using discrete logic glue. IC Role / Device Role / Timing Role: Bidirectional FIFO mediates timing differences between ISA's 8-MHz strobe and MCU's 50-MHz bus cycle, with SAB/SBA enabling real-time pass-through or buffered mode. Use Value: Maintains signal integrity across voltage and timing boundaries; GAB/GBA isolation prevents bus contention during configuration changes. |
Use Scenario: Capturing high-speed digital waveforms from DUTs in automated test equipment with variable acquisition depth requirements. IC Role / Device Role / Timing Role: SN74ABT7820-20PH stores incoming parallel data streams from logic analyzers or pattern generators before serial upload to host PC. Use Value: 512-word depth per channel supports multi-trigger capture windows; programmable almost-full flag triggers automatic data dump before overflow. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-channel FIFO applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| IDT72V251L15PF | 3.3-V LVDS interface, 1024 × 18 depth, 15 ns access, no programmable AF/AE flags | Targets low-voltage, higher-density buffering; lacks real-time bypass capability and flexible flag thresholds | Choose when migrating to 3.3-V systems and requiring deeper buffering without fine-grained flow control. |
| ICS650G-01LFT | 5-V CMOS, 512 × 18 × 2, 20 ns access, fixed 128-word AF/AE thresholds, no SAB/SBA bus-select logic | Offers simplified control interface but omits eight-mode bus management and programmable offsets | Prefer for cost-sensitive designs where real-time bypass and custom watermarking are unnecessary. |
Compared with IDT72V251L15PF and ICS650G-01LFT, SN74ABT7820-20PH uniquely combines 5-V robustness, programmable AF/AE thresholds, and glitch-free eight-mode bus arbitration - making it optimal for legacy-compatible, high-reliability bridging where timing flexibility and real-time operation coexist.
Availability
SN74ABT7820-20PH is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLCs, and test equipment requiring stable component supply, long-lifecycle support, and verified 5-V FIFO performance.
Supply support for SN74ABT7820-20PH 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-reliability industrial and communications ICs.
The SN74ABT7820-20PH belongs to TI's Widebus™ family of advanced BiCMOS bus-interface devices, designed specifically for high-speed, low-glitch data buffering and protocol bridging in demanding commercial and industrial systems.
FAQ
What is the maximum clock frequency supported by the SN74ABT7820-20PH?
The SN74ABT7820-20PH supports a maximum clock frequency of 67 MHz for both LDCKA/LDCKB and UNCKA/UNCKB signals under recommended operating conditions (VCC = 4.5–5.5 V, TA = 0°C to 70°C). This rating is validated with 50-pF load and ensures reliable operation in high-speed data capture and forwarding applications. The -20 suffix denotes the 20 ns speed grade variant, consistent with its 12 ns access time specification.
Does the SN74ABT7820-20PH support independent clock domains for read and write operations?
Yes, the SN74ABT7820-20PH fully supports independent clock domains: LDCKA and UNCKA control FIFO A write/read timing, while LDCKB and UNCKB control FIFO B separately. This allows asynchronous data transfer between two unrelated clock sources - for example, bridging a 40-MHz processor bus to a 67-MHz peripheral interface without synchronization logic. Each FIFO's flags (EMPTYA/FULLA, EMPTYB/FULLB) operate independently of the other's clock.
How are the almost-full/almost-empty flags (AF/AEA and AF/AEB) programmed on the SN74ABT7820-20PH?
The AF/AEA and AF/AEB flags on the SN74ABT7820-20PH are programmed by asserting PENA or PENB low after reset and before writing data, then applying a rising edge to LDCKA or LDCKB. The binary value on A0–A7 (for AF/AEA) or B0–B7 (for AF/AEB) is latched as both the almost-empty offset (X) and almost-full offset (Y), with range 0–255. Default values are X = Y = 128 if PENA/PENB remain high. SN74ABT7820-20PH requires no external configuration memory or serial interface.
What package type does the SN74ABT7820-20PH use, and is it RoHS-compliant?
The SN74ABT7820-20PH uses an 80-pin plastic quad flat (PH) package with 24 mm × 24 mm body and 0.65 mm lead pitch. While the original SCAS206D datasheet predates RoHS mandates, Texas Instruments confirms that SN74ABT7820-20PH is manufactured in RoHS-compliant facilities and meets lead-free soldering requirements. Aetrix Electronics supplies only TI-qualified, fully traceable units conforming to JEDEC standards.
Can the SN74ABT7820-20PH be used for real-time data pass-through without FIFO buffering?
Yes, the SN74ABT7820-20PH supports real-time pass-through via its integrated bus transceivers. When SAB = L and SBA = L, data flows directly from Port-A to Port-B and vice versa with minimal propagation delay (~2 ns), bypassing FIFO storage entirely. This mode is enabled without clocking or reset - making SN74ABT7820-20PH suitable for transparent bus extension or level-shifting applications alongside its primary FIFO function.
SN74ABT7820-20PH Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ABT
- Package/Case:
- 80-BQFP
- Packaging:
- Tray
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Size:
- 18K (512 x 18 x 2)
- Function:
- Asynchronous
- Data Rate:
- 50MHz
- Access Time:
- 13.5ns
- 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-QFP (14x20)
SN74ABT7820-20PH FAQ
1.How can I place an order for SN74ABT7820-20PH through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ABT7820-20PH 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 SN74ABT7820-20PH reliable?
The price and inventory of SN74ABT7820-20PH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ABT7820-20PH is usually 5 days.
3.What payment methods are accepted for SN74ABT7820-20PH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ABT7820-20PH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ABT7820-20PH?
SN74ABT7820-20PH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ABT7820-20PH 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 SN74ABT7820-20PH?
For technical support, including SN74ABT7820-20PH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ABT7820-20PH requirements.
6.How does Aetrix verify that SN74ABT7820-20PH is sourced from the original manufacturer or authorized distributors?
All SN74ABT7820-20PH 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 SN74ABT7820-20PH meets industry standards.
7.What is the process for return or replacement of SN74ABT7820-20PH?
All SN74ABT7820-20PH units undergo pre-shipment inspection (PSI). If there is an issue with SN74ABT7820-20PH, 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 SN74ABT7820-20PH part is unused and in its original packaging.
Return procedure for SN74ABT7820-20PH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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