Renesas 72255LA20PF8

Overview

IDT72255LA20PF8 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 - used in telecom data buffering, video frame synchronization, and network packet queuing.

For engineers reviewing the IDT72255LA20PF8 datasheet, IDT72255LA20PF8 pinout, IDT72255LA20PF8 application, or IDT72255LA20PF8 equivalent, key selection considerations include FWFT/IDT Standard timing mode configuration, dual-clock domain operation (RCLK/WCLK up to 100 MHz), industrial temperature support (–40°C to +85°C), TQFP-64 packaging, and retransmit functionality for deterministic data replay.

Technical Context

The IDT72255LA20PF8 implements a 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 earlier SuperSync FIFOs. Its internal RAM array (8,192 × 18) feeds into separate input/output registers, enabling simultaneous read and write operations without arbitration logic.

It supports two mutually exclusive timing modes selected at Master Reset: IDT Standard mode (EF/FF flag behavior, REN-gated reads) and First Word Fall Through (FWFT) mode (OR/IR flag behavior, immediate first-word output after three RCLK edges). Flag logic includes triple-buffered OR in FWFT mode and double-buffered EF/FF in IDT Standard mode for metastability immunity.

Key Specifications

Pinout & Package

Package: 64-pin Thin Quad Flat Pack (TQFP), order code PF, 10 mm × 10 mm body, 0.5 mm pitch - RoHS-compliant green variant available.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT72255LA15PF8, the IDT72255LA20PF8 delivers 20% higher clock frequency headroom and tighter 12 ns access time for demanding real-time pipelines; versus NB7L14M, it offers native 18-bit parallel I/O, simpler timing closure, and direct compatibility with legacy 5V microcontroller buses.

Availability

IDT72255LA20PF8 is available at Aetrix Electronics and suitable for telecom infrastructure, industrial gateways, broadcast video equipment, and radar signal processing systems requiring stable component supply across extended product lifecycles.

Supply support for IDT72255LA20PF8 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 FIFO solutions for communications and computing markets.

IDT72255LA20PF8 belongs to the SuperSync FIFO™ family - engineered for deterministic, low-latency data buffering in multi-clock-domain systems where jitter absorption, protocol bridging, and flow-control precision are critical.

FAQ

What is the maximum operating frequency of the IDT72255LA20PF8?

The IDT72255LA20PF8 supports a maximum clock cycle time of 20 ns, corresponding to a 50 MHz clock frequency. Its AC specifications guarantee full functionality up to this rate under industrial conditions (–40°C to +85°C, VCC = 5.0 V ±10%). The device achieves 100 MHz effective throughput in FWFT mode due to overlapping read/write operations, but individual RCLK/WCLK inputs are rated to 50 MHz.

Does the IDT72255LA20PF8 support both IDT Standard and FWFT timing modes?

Yes, the IDT72255LA20PF8 supports both timing modes. The mode is selected at Master Reset (MRS) based on the logic level of the FWFT/SI pin: HIGH selects FWFT mode (enabling first-word fall-through), LOW selects IDT Standard mode (requiring REN assertion for all reads). Both modes are fully supported in the same IDT72255LA20PF8 silicon - no hardware variants exist.

How is the programmable Almost-Empty flag (PAE) configured on the IDT72255LA20PF8?

The PAE flag threshold is loaded into an internal 18-bit offset register via serial or parallel programming. At Master Reset, LD pin state selects the method: LOW enables parallel load via D0–D17, HIGH enables serial load via SI. Default offsets are 127 (parallel) or 1,023 (serial). Reprogramming is allowed anytime post-reset using the same control sequence defined in Figure 4 of the datasheet.

Can the IDT72255LA20PF8 be used in a cascaded (chained) configuration for increased depth?

Yes - the IDT72255LA20PF8 supports depth expansion in FWFT mode. By connecting Q0–Q17 outputs of one device to D0–D17 inputs of the next, and synchronizing RCLK/WCLK across both, the chain behaves as a single deeper FIFO. No external logic is needed because FWFT's automatic output propagation eliminates the need for handshaking signals between stages.

What is the purpose of the Retransmit (RT) function in the IDT72255LA20PF8?

The Retransmit (RT) function resets the read pointer to zero on the rising edge of RCLK, allowing the same data sequence to be read again without rewriting. This is essential in applications like radar calibration or protocol replay testing, where deterministic re-access to buffered data is required. RT does not affect the write pointer or flag states - only the read address is modified.