Renesas 72235LB15TFGI8

Overview

72235LB15TFGI8 from Integrated Device Technology (IDT) is a 2,048 × 18-bit synchronous FIFO memory IC with dual-clock operation, 15 ns clock cycle time, industrial temperature range (–40°C to +85°C), and TQFP-64 package. It supports programmable Almost-Empty/Almost-Full flags, Half-Full flag, and depth/width expansion for buffering in high-speed interprocessor communication and LAN controllers.

For engineers reviewing the 72235LB15TFGI8 datasheet, 72235LB15TFGI8 pinout, 72235LB15TFGI8 application, or 72235LB15TFGI8 equivalent, key selection considerations include its 18-bit bidirectional data width, asynchronous read/write clock support, 10 ns read/write cycle capability (typical), and industrial-grade reliability for embedded data-path buffering.

Technical Context

This device implements a dual-port zero fall-through time architecture with independent read and write pointer logic, offset register programming via LD/WEN/REN control, and synchronized status flags (EF/FF) tied to respective clocks. Its submicron CMOS process enables low-power active operation (≤60 mA ICC1) while maintaining 100 MHz maximum clock frequency at 5 V.

The FIFO supports three operational modes: single-device (FL/WXI/RXI grounded), width expansion (parallel data bus widening), and daisy-chain depth expansion (via WXO/RXO signaling). Programmable flags use dedicated 12-bit offset registers loaded on WCLK/RCLK edges under LD assertion, with default offsets of 127 for PAE/PAF.

Key Specifications

Pinout & Package

72235LB15TFGI8 is housed in a 64-lead thin quad flatpack (TQFP) with exposed thermal pad (STQFP/TF package code), compliant with JEDEC MO-220, and features eight ground pins and five VCC pins for noise suppression and power distribution.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT72235L15TFGI, 72235LB15TFGI8 adds industrial temperature qualification and enhanced ESD robustness; compared with ICS72235B15TFGI8, it shares identical specs but reflects original IDT branding and legacy documentation traceability.

Availability

72235LB15TFGI8 is available at Aetrix Electronics and suitable for optical disk controllers, industrial Ethernet switches, multi-processor communication links, and real-time motion control systems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 72235LB15TFGI8 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, is a fabless semiconductor company specializing in timing, memory interface, RF, and sensor solutions for communications, computing, and industrial markets.

The IDT722xxLB family was designed specifically for high-speed, low-latency data buffering in clock-domain crossing applications-emphasizing deterministic timing, expandability, and industrial reliability.

FAQ

What is the memory organization of the 72235LB15TFGI8?

The 72235LB15TFGI8 implements a 2,048 × 18-bit synchronous FIFO memory array, providing 36,864 bits of first-in, first-out buffering. This configuration supports 18-bit parallel data paths and is optimized for applications requiring deep, deterministic buffering between asynchronous clock domains, such as interprocessor communication and network interface controllers.

Does the 72235LB15TFGI8 support both single-clock and dual-clock operation?

Yes, the 72235LB15TFGI8 supports both configurations: tying RCLK to WCLK enables single-clock operation, while independent clock inputs allow true dual-clock asynchronous mode. In dual-clock mode, EF is synchronized to RCLK and FF to WCLK, ensuring accurate status reporting in each domain-critical for the 72235LB15TFGI8's role in clock-domain isolation.

What are the default values for the programmable Almost-Empty and Almost-Full offsets in the 72235LB15TFGI8?

The 72235LB15TFGI8 defaults to an offset of 127 words for both the Programmable Almost-Empty (PAE) and Programmable Almost-Full (PAF) flags after reset. These values are stored in the internal 12-bit offset registers and can be reprogrammed via the LD/WEN/RCLK sequence, enabling flexible flow-control thresholds tailored to specific system latency and buffer management needs.

How does the Half-Full flag (HF) function in the 72235LB15TFGI8?

In single-device mode, the 72235LB15TFGI8's HF pin asserts LOW when exactly 1,024 words (half of 2,048) are stored, and remains LOW until the word count drops to ≤1,023. HF is asynchronous and updated on WCLK edges, providing a symmetrical status signal useful for balanced read/write scheduling-especially valuable in real-time streaming applications where the 72235LB15TFGI8 serves as a central data alignment buffer.

Is the 72235LB15TFGI8 pin-compatible with other members of the IDT722xxLB family?

No-while all IDT722xxLB devices share the same 64-pin TQFP package and core pinout, depth-specific variants (e.g., 72225LB, 72245LB) differ in internal memory size and flag timing parameters. The 72235LB15TFGI8 is not pin-compatible with shallower or deeper variants due to differences in internal pointer logic and flag generation, though expansion pins (WXO/RXO) maintain consistent behavior across the family.