Renesas 72255LA15PFI8

Overview

IDT72255LA15PFI8 from Integrated Device Technology is a high-speed, 8,192 × 18-bit synchronous CMOS FIFO memory with independent read/write clocks, 15 ns clock cycle time, fixed 8 ns access time, and industrial temperature support (–40°C to +85°C). It implements SuperSync architecture for low-latency data buffering in telecom and networking interfaces requiring depth expansion and retransmit capability.

For engineers reviewing the IDT72255LA15PFI8 datasheet, IDT72255LA15PFI8 pinout, IDT72255LA15PFI8 application, or IDT72255LA15PFI8 equivalent, key selection criteria include its FWFT/IDT Standard timing mode configurability, programmable almost-empty/almost-full flags, auto power-down, and compatibility with TQFP-64 packaging for board-level integration in high-throughput serial data paths.

Technical Context

This FIFO eliminates inter-clock frequency constraints-RCLK and WCLK operate fully independently up to 66.7 MHz without requiring FS pin configuration. Its dual timing modes (IDT Standard and First Word Fall Through) are selected at master reset via FWFT/SI, with FWFT enabling immediate first-word output after three RCLK edges without REN assertion.

The device integrates dedicated offset registers for PAE and PAF flags, programmable via parallel (D0–D17) or serial (SI) methods using LD/SEN/WCLK control. Retransmit (RT) resets the read pointer to zero on rising RCLK while preserving write pointer and flag settings, supporting repeat-read protocols in packet reassembly applications.

Key Specifications

Pinout & Package

Package: 64-pin Thin Quad Flat Pack (TQFP), PN64 order code, 10 mm × 10 mm body, 0.5 mm pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT72255LA20PFI8, the IDT72255LA15PFI8 delivers 33% higher throughput and tighter timing margins; versus NB3N502DG, it adds FWFT, retransmit, and dual-offset flag control essential for adaptive data flow management.

Availability

IDT72255LA15PFI8 is available at Aetrix Electronics and suitable for telecom infrastructure, industrial Ethernet switching, and medical imaging equipment requiring stable component supply across extended product lifecycles.

Supply support for IDT72255LA15PFI8 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

Integrated Device Technology (IDT), now part of Renesas Electronics, designs high-performance timing, memory interface, and RF solutions for communications and computing markets.

IDT72255LA15PFI8 belongs to the SuperSync FIFO family engineered for deterministic, low-latency data buffering in multi-clock-domain systems such as network processors, video encoders, and test equipment.

FAQ

What timing modes does the IDT72255LA15PFI8 support, and how is mode selection performed?

The IDT72255LA15PFI8 supports two timing modes: IDT Standard and First Word Fall Through (FWFT). Mode selection occurs during Master Reset (MRS) based on the logic level of the FWFT/SI pin: LOW selects IDT Standard mode (EF/FF flags, REN required for all reads), HIGH selects FWFT mode (OR/IR flags, first word appears automatically after three RCLK edges). This configuration is latched and remains active until next MRS.

How does the retransmit (RT) function operate in the IDT72255LA15PFI8, and what is preserved during its execution?

In the IDT72255LA15PFI8, asserting RT low on a rising RCLK edge resets the read pointer to zero, enabling reread of the FIFO's first stored word. Crucially, the write pointer, timing mode (FWFT/IDT Standard), flag offset settings (PAE/PAF), and programming method (serial/parallel) remain unchanged. This allows repeat-read operations without disrupting ongoing write activity or configuration state.

What are the default programmable flag offset values for PAE and PAF in the IDT72255LA15PFI8, and how are they determined?

The IDT72255LA15PFI8 defaults to PAE = 127 and PAF = 127 when LD is LOW during Master Reset (enabling parallel programming), or PAE = 1,023 and PAF = 1,023 when LD is HIGH (enabling serial programming). These values are stored in dedicated offset registers and define the word-count thresholds at which PAE goes LOW (near-empty) and PAF goes LOW (near-full), providing flexible flow control granularity.

Can the IDT72255LA15PFI8 be used in depth-expanded configurations, and what design requirement enables this?

Yes, the IDT72255LA15PFI8 supports depth expansion by cascading multiple devices in series, enabled specifically by its FWFT timing mode. In FWFT mode, the output of one FIFO directly feeds the input of the next without external logic, because the first word appears immediately on Q0–Q17 after three RCLK edges-eliminating the need for handshaking signals between stages and simplifying multi-depth buffer design.

What is the significance of the Partial Reset (PRS) function in the IDT72255LA15PFI8, and how does it differ from Master Reset (MRS)?

Partial Reset (PRS) in the IDT72255LA15PFI8 resets only the read and write pointers to zero while preserving all configuration state-including timing mode (FWFT/IDT Standard), flag offset values, and serial/parallel programming method. Unlike MRS, which reinitializes all settings, PRS allows mid-operation buffer clearing without losing customized flag thresholds or operational mode, making it ideal for dynamic flow control in real-time systems.