Infineon Technologies CY7C4251V-15AC

Overview

CY7C4251V-15AC from Cypress Semiconductor is an 8K × 9-bit synchronous FIFO memory with 3.3 V supply, 66 MHz operation (15 ns cycle time), 5 V-tolerant inputs, and programmable Almost Empty/Almost Full flags. It serves as a high-speed data buffer in multi-processor interconnects and communications interfaces requiring deterministic latency and depth expansion capability.

For engineers reviewing the CY7C4251V-15AC datasheet, CY7C4251V-15AC pinout, CY7C4251V-15AC application, or CY7C4251V-15AC equivalent, key selection criteria include synchronous flag timing alignment (RCLK/WCLK domain separation), 9-bit bus width, 8K-depth buffering, and dual-write-enable configuration support for depth expansion.

Technical Context

The CY7C4251V-15AC implements a dual-clock, fully asynchronous FIFO architecture with independent RCLK and WCLK domains. Its status flags (EF, FF, PAE, PAF) are strictly synchronized-EF/PAE to RCLK, FF/PAF to WCLK-ensuring deterministic timing behavior across clock domains.

It supports two operational modes selected at reset via WEN2/LD pin state: dual-write-enable mode for depth expansion or single-write-enable + programmable flag mode. Flag offsets are stored in four 8-bit registers (empty LSB/MSB, full LSB/MSB), defaulting to 7 words for both Almost Empty and Almost Full thresholds.

Key Specifications

Pinout & Package

The CY7C4251V-15AC is housed in a 32-pin Thin Quad Flat Package (TQFP) with exposed pad, optimized for thermal dissipation and signal integrity in high-speed digital systems.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT72V2115L15PF, CY7C4251V-15AC offers superior configurability via WEN2/LD mode selection and finer-grained flag programming, while NB3N502MNR2G serves a fundamentally different circuit role and is not a functional alternative.

Availability

CY7C4251V-15AC is available at Aetrix Electronics and suitable for high-speed data acquisition, multi-processor interconnect, and serial protocol bridging requiring stable component supply and long-term industrial lifecycle support.

Supply support for CY7C4251V-15AC 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 fabless semiconductor company specializing in microcontrollers, memory, and programmable solutions for embedded systems.

The CY7C42X1V series was designed specifically for high-throughput, low-latency data buffering in mixed-clock-domain systems, targeting industrial automation, test equipment, and communications infrastructure.

FAQ

Is a power-on reset pulse mandatory before using CY7C4251V-15AC?

Yes. An active-HIGH RS pulse is required after VCC stabilization to initialize internal pointers and guarantee EF=LOW. Without this reset, flag states and pointer positions are undefined, risking data corruption or incorrect empty/full assertions. The minimum RS pulse width is specified as 10 ns in the datasheet.

Can RCLK and WCLK be tied together for single-clock operation?

Yes. The device supports single-clock mode by connecting RCLK and WCLK. In this configuration, read and write operations are synchronized to the same edge, simplifying timing analysis but eliminating true asynchronous buffering capability. All status flags remain valid and update on that shared clock edge.

What happens to Q0–Q8 outputs when the FIFO is empty and additional reads occur?

When EF=LOW (empty), further read attempts do not change Q0–Q8 - they retain the last valid data word driven onto the bus. This hold behavior prevents bus contention or undefined values during underflow conditions and eliminates need for external latching logic.

How is the Almost Empty threshold programmed, and what is its default value?

The Almost Empty threshold is set by writing to the 16-bit Empty Offset register (LSB + MSB) via WEN2/LD and WCLK in load mode. Default value is 007h (7 decimal), meaning PAE goes LOW when ≤7 unread words remain. Programming occurs sequentially across four WCLK edges with WEN1 and WEN2/LD both LOW.