Renesas 72255LA20PFI8

Overview

IDT72255LA20PFI8 from Integrated Device Technology, Inc. is a high-speed, 8,192 × 18-bit synchronous CMOS FIFO memory with independent read/write clocks, 10 ns clock cycle time, fixed low-latency first-word access, and programmable Almost-Empty/Almost-Full flags - deployed in telecom line cards for buffering bursty packet data between ASICs operating at mismatched clock domains.

For engineers reviewing the IDT72255LA20PFI8 datasheet, IDT72255LA20PFI8 pinout, IDT72255LA20PFI8 application, or IDT72255LA20PFI8 equivalent, key selection considerations include FWFT vs. IDT Standard timing mode configuration, programmable flag offset loading method (serial/parallel), retransmit functionality for packet replay, industrial temperature support (–40°C to +85°C), and TQFP-64 package compatibility with depth-expansion chaining.

Technical Context

This FIFO implements fully asynchronous dual-clock architecture: RCLK and WCLK operate independently from 0 to 100 MHz with no frequency ratio constraint - eliminating the FS pin required in prior SuperSync generations. The internal RAM array is paired with triple-register-buffered OR output in FWFT mode and double-register-buffered EF/FF in IDT Standard mode to ensure timing robustness across voltage and temperature.

Flag logic supports two configurable timing modes selected at Master Reset via FWFT/SI: IDT Standard requires explicit REN assertion for every read, while FWFT delivers the first word to Q0–Q17 after three RCLK edges without REN. Retransmit (RT) resets the read pointer to zero on rising RCLK, enabling deterministic replay of buffered frames without disturbing write operations or flag settings.

Key Specifications

Pinout & Package

Package: 64-pin Thin Quad Flat Pack (TQFP), 10 mm × 10 mm, 0.5 mm pitch - compatible with standard SMT assembly and thermal pad-reflow profiles.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT72255LA20PFI8, the 72255LA15PFI8 trades 33% bandwidth for reduced power and cost, while the 72255LA20PFIG8 maintains identical performance with lead-free termination - both share full functional and pinout compatibility but differ in speed grade and finish compliance.

Availability

IDT72255LA20PFI8 is available at Aetrix Electronics and suitable for telecom infrastructure, industrial gateways, broadcast video systems, and automated test equipment requiring stable component supply across extended product lifecycles.

Supply support for IDT72255LA20PFI8 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, Inc. (IDT) is a fabless semiconductor company specializing in timing, memory interface, RF, and high-performance interconnect solutions for communications and computing markets.

IDT72255LA20PFI8 belongs to the SuperSync FIFO™ family - designed specifically for high-reliability, low-latency data buffering in multi-clock-domain systems where deterministic timing and expandable depth are critical.

FAQ

What is the maximum operating frequency of the IDT72255LA20PFI8?

The IDT72255LA20PFI8 supports a maximum clock cycle time of 10 ns, corresponding to a 100 MHz operating frequency for both RCLK and WCLK. This specification is guaranteed under industrial conditions (–40°C to +85°C, VCC = 5V ±10%) and applies equally to IDT Standard and FWFT timing modes. The device achieves this performance using high-speed submicron CMOS technology and has no inter-clock frequency ratio restrictions.

How does the IDT72255LA20PFI8 handle clock domain crossing between write and read interfaces?

The IDT72255LA20PFI8 uses fully asynchronous dual-clock architecture: RCLK and WCLK operate independently from 0 to 100 MHz with no frequency relationship required. Its internal pointer logic and flag synchronization circuits eliminate metastability risks. Status flags (EF/OR, FF/IR, HF, PAE, PAF) are registered to their respective clocks, and the device guarantees safe data transfer across arbitrary clock ratios - validated by tSKEW1–tSKEW4 timing parameters in the datasheet.

Can the IDT72255LA20PFI8 be used in FWFT mode for zero-Ren first-word access?

Yes - the IDT72255LA20PFI8 enters FWFT mode when FWFT/SI is held HIGH during Master Reset (MRS). In this mode, the first word written to an empty FIFO appears on Q0–Q17 after exactly three RCLK rising edges, without requiring REN assertion. Subsequent words still require REN activation. The OR (Output Ready) flag goes LOW to signal valid data availability, and OR is triple-register-buffered to ensure timing integrity.

What is the purpose of the Retransmit (RT) function in the IDT72255LA20PFI8?

The Retransmit (RT) function in the IDT72255LA20PFI8 allows deterministic replay of buffered data: asserting RT low on a rising RCLK edge resets the read pointer to zero, causing the FIFO to re-output its contents from the beginning. This occurs without affecting the write pointer, flag settings, timing mode, or programmable offsets - making it ideal for packet retransmission in networking or waveform replay in test equipment.

Is the IDT72255LA20PFI8 compatible with lead-free PCB assembly processes?

The IDT72255LA20PFI8 uses SnPb (tin-lead) lead finish and is marked as End-of-Life (EOL) with Last Time Buy expiring June 15, 2018. For lead-free compliance, the pin-compatible IDT72255LA20PFIG8 variant is available - identical in speed, functionality, and package (TQFP-64), but with green (RoHS-compliant) termination. Migration to PFIG8 is recommended for new designs requiring long-term manufacturability.