Texas Instruments SN74ABT7820-20PN

Overview

SN74ABT7820-20PN 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 50 MHz clock rate, 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 SN74ABT7820-20PN datasheet, SN74ABT7820-20PN pinout, SN74ABT7820-20PN application, or SN74ABT7820-20PN equivalent, this page delivers verified functional architecture, timing-critical pin roles, real-world bus-management use cases, and validated alternative parts for FIFO-based system synchronization and data buffering.

Technical Context

The SN74ABT7820-20PN implements dual asynchronous FIFO cores with independent load/unload clocks (LDCKA/UNCKA and LDCKB/UNCKB), enabling simultaneous bidirectional data streaming without shared clock domain constraints. Its select-mode control logic (SAB/SBA) and output-enable circuitry (GAB/GBA) support eight distinct bus-management functions including real-time pass-through and FIFO-stored data routing.

Each FIFO supports programmable AF/AE flag offsets (X/Y) via PENA/PENB latching on LDCKA/LDCKB edges, with default 128-word thresholds. Flag outputs (EMPTYA/FULLA/HFA/AF/AEA and corresponding B-side signals) provide deterministic status reporting for hardware handshaking and flow control in high-throughput digital systems.

Key Specifications

Pinout & Package

SN74ABT7820-20PN uses an 80-pin Thin Quad Flat Package (PN) with 0.5-mm lead pitch and 12 mm × 12 mm body size, optimized for automated SMT assembly and thermal dissipation in high-density boards.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar FIFO memory applications.

Compared with IDT72V2115L15PF and SN74V293-15PAG, the SN74ABT7820-20PN uniquely delivers dual independent FIFOs with strobed bidirectional operation at 5 V, making it irreplaceable in applications requiring simultaneous full-duplex data flow control without external logic or voltage translation.

Availability

SN74ABT7820-20PN is available at Aetrix Electronics and suitable for telecom infrastructure, industrial automation, broadcast video equipment, and embedded computing systems requiring stable component supply across long production lifecycles.

Supply support for SN74ABT7820-20PN 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-performance interface and memory products.

The SN74ABT7820-20PN belongs to TI's Widebus™ family of advanced BiCMOS bus-interface devices, engineered specifically for high-speed, low-glitch data buffering and bus arbitration in demanding digital systems.

FAQ

What is the maximum guaranteed clock frequency for SN74ABT7820-20PN?

The SN74ABT7820-20PN is rated for a maximum clock frequency of 50 MHz, as specified in the timing requirements table for the -20 speed grade. This applies to both LDCKA/LDCKB and UNCKA/UNCKB inputs under recommended operating conditions (VCC = 4.5 V to 5.5 V, TA = 0°C to 70°C). Operation beyond 50 MHz is not characterized or guaranteed.

How does the programmable AF/AEA flag work in SN74ABT7820-20PN?

In SN74ABT7820-20PN, the AF/AEA flag becomes active high when FIFO A contains ≤X words (almost-empty) or ≥(512–Y) words (almost-full). After reset, PENA low enables latching of A0–A7 as X on the next LDCKA rising edge; a second LDCKA pulse latches Y. Default X=Y=128 if PENA remains high.

Can SN74ABT7820-20PN operate with mixed 3.3-V and 5-V logic interfaces?

No-SN74ABT7820-20PN requires a 4.5 V to 5.5 V supply and is designed for 5-V TTL/CMOS logic levels. Its VIH (2.0 V min) and VIL (0.8 V max) thresholds and output drive characteristics are incompatible with direct 3.3-V interface without level-shifting circuitry, as confirmed by absolute maximum and recommended operating conditions.

What package type does SN74ABT7820-20PN use, and what are its key mechanical features?

SN74ABT7820-20PN uses an 80-pin Thin Quad Flat Package (PN) with 0.5-mm lead pitch and 12 mm × 12 mm body dimensions. It features gull-wing leads for standard reflow soldering and a thermal impedance (θJA) of 62°C/W, supporting reliable operation in convection-cooled industrial environments.

Does SN74ABT7820-20PN support simultaneous read and write operations on the same FIFO?

No-each FIFO in SN74ABT7820-20PN supports either read or write per clock edge, not true simultaneous R/W. LDCKx controls writes and UNCKx controls reads; they may be active concurrently on *different* FIFOs (e.g., LDCKA + UNCKB), but not on the same FIFO core due to internal address pointer architecture.