Infineon Technologies CY7C4255-15AXC

Overview

CY7C4255-15AXC from Cypress Semiconductor is an 8K × 18-bit, high-speed asynchronous FIFO memory with 10 ns read/write cycle time, 66.7 MHz maximum clock frequency, and TTL-compatible I/O. It supports independent read/write clocks, programmable Almost Empty/Almost Full flags, and retransmit functionality. Used in high-speed data acquisition systems where deterministic latency and depth buffering are required.

For engineers reviewing the CY7C4255-15AXC datasheet, CY7C4255-15AXC pinout, CY7C4255-15AXC application, or CY7C4255-15AXC equivalent, key selection criteria include synchronous/asynchronous flag timing control (via VCC/SMODE), cascade expansion capability (WXO/RXO/FL), and industrial-grade 5V ±10% operation at –40°C to +85°C.

Technical Context

The CY7C4255-15AXC implements a dual-clock, fully asynchronous FIFO architecture with separate WCLK/REN and RCLK/WEN control paths. Its 8K × 18-bit RAM array supports simultaneous read/write operations without bus contention, and status flags (EF, FF, PAE, PAF, WXO/HF) are synchronized to respective clocks-EF/PAE to RCLK, FF/PAF to WCLK-ensuring deterministic timing in mixed-clock domains.

Flag behavior is configurable via VCC/SMODE: tying to VSS enables synchronous Almost Empty/Almost Full flags (PAE/PAF aligned to RCLK/WCLK edges), while tying to VCC yields asynchronous operation. The device also supports depth expansion using WXI/WXO and RXI/RXO pins with FL pin sequencing, and includes a dedicated Retransmit (RT) function triggered via FL/RT strobing.

Key Specifications

Pinout & Package

64-pin Thin Quad Flat Package (TQFP) with center power/ground pins to minimize switching noise. Pin layout optimized for signal integrity in high-speed FIFO applications, with dedicated RCLK/WCLK inputs, OE-controlled 18-bit tri-state outputs (Q0–Q17), and dual-mode expansion pins (WXO/HF, FL/RT).

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT72205L15TPG and SN74V293-15PAG, the CY7C4255-15AXC uniquely combines native 18-bit width, 5V TTL compatibility, programmable flag synchronization, and hardware retransmit-making it optimal for industrial 5V systems requiring deterministic, expandable buffering without glue logic.

Availability

CY7C4255-15AXC is available at Aetrix Electronics and suitable for high-speed data acquisition, multiprocessor interfacing, and communications protocol buffering requiring stable component supply across industrial temperature ranges and long-term production cycles.

Supply support for CY7C4255-15AXC 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

Cypress Semiconductor (now part of Infineon Technologies) is a U.S.-based semiconductor company specializing in programmable system-on-chip solutions, memory, and interface ICs for industrial, automotive, and consumer applications.

The CY7C4255 belongs to Cypress's Deep Sync FIFO product line, designed specifically for deterministic, low-latency data buffering in mixed-clock-domain systems such as test equipment, communications infrastructure, and real-time control.

FAQ

What is the function of the VCC/SMODE pin on CY7C4255-15AXC?

The VCC/SMODE pin configures the timing behavior of the Programmable Almost Empty (PAE) and Programmable Almost Full (PAF) flags. When tied to VSS, PAE synchronizes to RCLK and PAF to WCLK; when tied to VCC, both operate asynchronously. This allows designers to select between deterministic flag timing or minimal latency based on system clock domain constraints.

How does the FL/RT pin support retransmit functionality in standalone mode?

In standalone mode (non-cascaded), FL/RT operates as a Retransmit (RT) input. A low-going pulse on this pin reloads the most recently read word onto the Q0–Q17 output bus, enabling protocol-level retries without CPU intervention. The pulse width must meet tPRT ≥ 35 ns (min) per datasheet specification.

Can CY7C4255-15AXC be used in depth-expanded configurations with CY7C4265A devices?

Yes-CY7C4255-15AXC is pin- and functionally compatible with CY7C4265A for depth expansion. The WXO, RXO, WXI, RXI, and FL pins operate identically across the CY7C42X5 family. However, total depth is limited by the smallest device in the chain (e.g., mixing 8K and 16K devices yields 8K × N depth).

What is the minimum reset pulse width required for reliable initialization?

The minimum reset pulse width (tRS) for CY7C4255-15AXC is 15 ns at the –15 speed grade. A valid reset pulse must hold RS LOW for ≥15 ns to ensure all internal pointers and flags initialize to empty state. Reset may be applied asynchronously relative to RCLK/WCLK, and clocks can remain free-running during reset.