Texas Instruments SN74ACT2227DW

Overview

SN74ACT2227DW from Texas Instruments is a dual independent FIFO memory IC with two 64 × 1-bit asynchronous first-in, first-out buffers. It supports free-running read/write clocks up to 60 MHz, delivers 9 ns access time, and features synchronized input-ready/output-ready flags, half-full, and almost-full/almost-empty status outputs. It is used in serial-data buffering for telecom elastic stores and time-division multiplexing systems.

For engineers reviewing the SN74ACT2227DW datasheet, SN74ACT2227DW pinout, SN74ACT2227DW application, or SN74ACT2227DW equivalent, key selection criteria include its 28-pin SOIC package, dual 64-word depth, 5 V operation, 3-state outputs, and asynchronous clock domain isolation between FIFOs.

Technical Context

The SN74ACT2227DW implements two independent synchronous FIFOs using dual-port SRAM architecture - each with dedicated write and read pointers, reset logic, and status register. Each FIFO uses low-to-high clock transitions for data capture (WRTCLK/RDCLK) and requires concurrent enable (WRTEN/RDEN) and flag (IR/OR) assertion for valid transfers.

Input-ready (IR) flags are synchronized to their respective write clocks via two-stage flip-flop chains; output-ready (OR) flags use three-stage synchronization to read clocks. Half-full (HF) and almost-full/almost-empty (AF/AE) flags provide programmable flow control thresholds - HF asserts at ≥32 bits stored; AF/AE asserts when ≤8 locations remain full or empty.

Key Specifications

Pinout & Package

Packaged in a 28-pin SOIC (DW) body with standard 0.300-inch width, gull-wing leads, and RoHS-compliant NiPdAu finish. MSL Level-1 rating supports uncompromised reflow compatibility.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ACT2229DW, the SN74ACT2227DW offers lower latency (shorter pointer traversal) and reduced power at equivalent clock rates; compared with 7200L15, it delivers native 1-bit serial support, dual independence, and direct SOIC compatibility - eliminating adapter logic and layout changes.

Availability

SN74ACT2227DW is available at Aetrix Electronics and suitable for telecom infrastructure, industrial serial bridges, protocol adapters, and time-division multiplexing systems requiring stable component supply across long production lifecycles.

Supply support for SN74ACT2227DW 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 SN74ACT2227DW belongs to TI's ACT advanced CMOS logic family - engineered for 5 V operation with TTL-compatible inputs, low power, and robust noise immunity in demanding serial-data buffering applications.

FAQ

What is the maximum supported clock frequency for SN74ACT2227DW?

The SN74ACT2227DW supports read and write clocks up to 60 MHz, as specified in the timing requirements section of its datasheet. This frequency applies independently to each FIFO's WRTCLK and RDCLK inputs, enabling high-speed serial data buffering for OC-1 telecom applications. The 9 ns access time and 5 ns minimum pulse width ensure reliable operation at this rate under recommended conditions (VCC = 4.5 V to 5.5 V, TA = –40°C to +85°C).

How does the reset sequence work on SN74ACT2227DW?

The SN74ACT2227DW requires a specific hardware reset sequence: four low-to-high transitions on both WRTCLK and RDCLK must occur while the corresponding RESET pin is held low. This initializes all internal pointers and sets IR and OR flags low, HF low, and AF/AE high. After reset, IR becomes high on the second WRTCLK edge; OR becomes high on the third RDCLK edge after the first word is loaded - ensuring predictable startup behavior for both FIFOs.

Can SN74ACT2227DW operate with asynchronous read and write clocks?

Yes, the SN74ACT2227DW is explicitly designed for asynchronous operation: each FIFO's WRTCLK and RDCLK may run at different frequencies, phases, or even be stopped independently. Input-ready (IR) and output-ready (OR) flags are synchronized to their respective clocks using multi-stage flip-flop chains - preventing metastability and enabling safe handshaking across clock domains without external synchronizers.

What do the AF/AE and HF flags indicate on SN74ACT2227DW?

On the SN74ACT2227DW, the AF/AE (almost-full/almost-empty) flag goes high when ≤8 bits are stored or ≤8 locations remain empty in a FIFO - providing early warning for flow control. The HF (half-full) flag asserts high when ≥32 bits are stored (i.e., half of 64). Both flags are asynchronous status outputs used to trigger multiplexer selects, suppress reads/writes, or initiate pulse stuffing - critical for jitter-tolerant serial buffering.

Is SN74ACT2227DW pin-compatible with SN74ACT2229DW?

Yes, the SN74ACT2227DW and SN74ACT2229DW share identical 28-pin SOIC (DW) packaging and pin assignments - including all control, status, clock, data, and power terminals. The only functional difference is FIFO depth: SN74ACT2227DW provides dual 64 × 1-bit buffers, while SN74ACT2229DW provides dual 256 × 1-bit buffers. No PCB change is required for substitution - firmware or system timing must accommodate the deeper buffer.