Texas Instruments SN74ACT7803-15DLR

Overview

SN74ACT7803-15DLR 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 67 MHz), 12 ns access time with 50-pF load, programmable almost-full/almost-empty flags, and bidirectional/width-expansion capability without external logic. Used in data rate bridging between mismatched clock domains.

For engineers reviewing the SN74ACT7803-15DLR datasheet, SN74ACT7803-15DLR pinout, SN74ACT7803-15DLR application, or SN74ACT7803-15DLR equivalent, key selection criteria include its 56-pin SSOP package, synchronous flag behavior (IR synchronized to WRTCLK, OR to RDCLK), reset timing requirements (four rising edges on both clocks), and compatibility with SN74ACT7805/SN74ACT7813 for footprint reuse.

Technical Context

The SN74ACT7803-15DLR implements a dual-clock FIFO architecture with separate synchronous write and read control paths. Its 512-word × 18-bit RAM core supports concurrent read/write operations when clocks are asynchronous or coincident, with input-ready (IR) and output-ready (OR) flags synchronized to their respective clock domains.

Status flag logic includes half-full (HF) and programmable almost-full/almost-empty (AF/AE) outputs, where AF/AE offset values (X/Y) are latched via D0–D7 during reset using PEN control. Reset requires four rising edges on both WRTCLK and RDCLK while RESET is asserted low, initializing IR, OR, and HF low and AF/AE high.

Key Specifications

Pinout & Package

Packaged in a 56-pin Shrink Small-Outline Package (SSOP, DL package), 300-mil body width with 25-mil center-to-center lead pitch. Features distributed V_CC/GND pins and TI's patented Output Edge Control (OEC™) circuitry to suppress simultaneous switching noise.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ACT7805-15DL and SN74ACT7813-15DL, the SN74ACT7803-15DLR offers identical pin compatibility and functional behavior but uses the industry-standard 64-word AF/AE default offset - making it the reference variant for legacy system replacements and broadest design reuse.

Availability

SN74ACT7803-15DLR is available at Aetrix Electronics and suitable for video frame buffering, bus protocol translation, and test equipment data capture requiring stable component supply and long-term industrial availability.

Supply support for SN74ACT7803-15DLR 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 over 50 years of innovation in high-reliability digital interface components.

The SN74ACT7803-15DLR belongs to TI's Widebus™ family of advanced CMOS FIFOs, engineered specifically for clock-domain isolation and high-speed data buffering in commercial-grade communication, instrumentation, and multimedia systems.

FAQ

What is the maximum operating frequency of the SN74ACT7803-15DLR?

The SN74ACT7803-15DLR supports a maximum clock frequency of 67 MHz for both read and write operations under recommended conditions (V_CC = 4.5 V to 5.5 V, T_A = 0°C to 70°C). This rating applies to the -15 speed grade and is validated with a 50-pF load and specified setup/hold times. The device maintains full functionality at lower frequencies, including 25 MHz, 40 MHz, and 50 MHz variants within the same family.

How does the reset sequence work on the SN74ACT7803-15DLR?

The SN74ACT7803-15DLR requires an asynchronous reset where RESET must be held low while at least four rising edges occur on both WRTCLK and RDCLK. This clears internal pointers and initializes flags: IR, OR, and HF go low; AF/AE goes high. The FIFO must be reset upon power-up to ensure deterministic behavior. Failure to meet the four-edge requirement may leave status flags in undefined states.

Can the SN74ACT7803-15DLR be used for bidirectional data flow without external logic?

Yes - two SN74ACT7803-15DLR devices can be configured in a back-to-back arrangement for true bidirectional buffering. Their independent clock domains and synchronized flags allow one device to handle transmit direction while the other handles receive, with no additional logic gates or controllers required. This is explicitly documented in TI's application note Figure 9.

What is the function of the PEN pin on the SN74ACT7803-15DLR?

The PEN (Program Enable) pin on the SN74ACT7803-15DLR allows dynamic programming of the almost-full/almost-empty (AF/AE) flag thresholds before the first write operation. When PEN is low during reset, the binary value on D0–D7 is latched as the X (almost-empty) and Y (almost-full) offset values. If PEN remains high, default values of X = Y = 64 are used. Writes are disabled while PEN is active for programming.

Is the SN74ACT7803-15DLR pin-compatible with other members of the ACT78xx FIFO family?

Yes - the SN74ACT7803-15DLR is pin-to-pin compatible with SN74ACT7805-15DL and SN74ACT7813-15DL, sharing identical 56-pin SSOP (DL) packaging, terminal functions, and signal routing. Differences are limited to internal AF/AE defaults and minor electrical specifications; no PCB changes are required when substituting within this group.