Renesas 72235LB10JG8

Overview

72235LB10JG8 from Integrated Device Technology (IDT) is a 2,048 × 18-bit synchronous FIFO memory IC with dual-clock operation, 10 ns read/write cycle time, and industrial temperature range (–40°C to +85°C), used for buffering high-speed data streams in LAN controllers and interprocessor communication links.

For engineers reviewing the 72235LB10JG8 datasheet, 72235LB10JG8 pinout, 72235LB10JG8 application, or 72235LB10JG8 equivalent, key selection criteria include its 18-bit bidirectional data width, programmable almost-empty/almost-full flags with default 127-word offsets, half-full flag capability, and support for depth expansion via daisy-chained WXO/RXO signals.

Technical Context

This device implements a dual-port zero fall-through time architecture with independent read and write pointer logic, enabling true asynchronous clock domain crossing between WCLK and RCLK. It uses high-performance submicron CMOS technology and features dedicated offset registers for PAE/PAF flag programming via LD/WEN/RCLK control sequences.

The FIFO supports three operational modes: single-device (FL/WXI/RXI grounded), width expansion (parallel data bus widening), and depth expansion (daisy-chain via WXI/WXO and RXI/RXO). Flag outputs (EF, FF, PAE, PAF, HF) are synchronized to their respective clocks-EF/PAE/PAF/HF to RCLK, FF to WCLK-ensuring deterministic timing behavior in mixed-clock systems.

Key Specifications

Pinout & Package

72235LB10JG8 is packaged in a 64-lead plastic leaded chip carrier (PLCC) with J suffix per ordering code, featuring eight ground pins and five VCC pins for noise immunity and power integrity in high-speed digital systems.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT72235LB10JG8, IDT72235LA10JG8 trades industrial temperature rating for lower cost and SnPb finish, while ICS72235B10JG8 maintains full functional equivalence with updated environmental compliance and manufacturer support under Renesas.

Availability

72235LB10JG8 is available at Aetrix Electronics and suitable for LAN controllers, interprocessor communication links, optical disk interfaces, and DSP data pipelines requiring stable component supply across industrial temperature ranges and long product lifecycles.

Supply support for 72235LB10JG8 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, and high-speed interconnect solutions for communications and computing markets.

The IDT722xxLB family was designed specifically for high-reliability, low-latency data buffering in industrial and telecom infrastructure where deterministic timing, dual-clock isolation, and expandable memory depth are essential.

FAQ

What is the memory organization and speed grade of the 72235LB10JG8?

The 72235LB10JG8 is a 2,048 × 18-bit synchronous FIFO with a 10 ns read/write cycle time, supporting up to 100 MHz clock operation. Its organization delivers 36,864 bits of buffer storage, and the "10" in the part number explicitly denotes the 10 ns speed grade per IDT's ordering convention. This specification is confirmed in the AC Electrical Characteristics table of the official datasheet.

Does the 72235LB10JG8 support both single-clock and dual-clock operation?

Yes, the 72235LB10JG8 supports both configurations: RCLK can be tied directly to WCLK for single-clock use, or operated independently for true dual-clock asynchronous buffering. The device's dual-port zero fall-through time architecture ensures correct operation in either mode, with flag synchronization (EF to RCLK, FF to WCLK) preserving timing integrity regardless of clock relationship.

What are the default values for the programmable Almost-Empty and Almost-Full offsets in the 72235LB10JG8?

The 72235LB10JG8 defaults to 127-word offsets for both PAE and PAF flags after reset, as specified for all members of the IDT72225LB/72235LB/72245LB series. These values are stored in dedicated 12-bit offset registers and can be reprogrammed via the LD/WEN/RCLK sequence using D0–D11 inputs, enabling application-specific watermark tuning without external logic.

How does the Half-Full flag (WXO/HF) function in single-device mode for the 72235LB10JG8?

In single-device configuration (FL/WXI/RXI grounded), the WXO/HF pin functions exclusively as a Half-Full flag: it asserts LOW when the FIFO contains ≥1,024 words (half of 2,048) and remains LOW until the count drops to ≤1,023. The flag is updated on the rising edge of WCLK and reset on the rising edge of RCLK, providing an asynchronous occupancy indicator useful for load-balancing decisions in streaming systems.

Is the 72235LB10JG8 pin-compatible with other devices in the IDT722xxLB family?

Yes, all IDT722xxLB variants-including 72205LB, 72215LB, 72225LB, 72235LB, and 72245LB-share identical 64-pin PLCC (J suffix) and TQFP (PF/TF suffix) footprints and pinouts. This allows direct PCB reuse across depth variants; only the memory depth and associated timing parameters differ, making the 72235LB10JG8 a drop-in option where 2,048-word capacity meets system requirements.