Infineon Technologies CY7C4251-15AC

Overview

CY7C4251-15AC from Cypress Semiconductor is an 8K × 9-bit synchronous FIFO memory with TTL-compatible I/O, 10 ns read/write cycle time, programmable Almost Empty/Almost Full flags, and dual-clock asynchronous operation. It serves as a high-speed data buffer in multiprocessor interconnects, communications interfaces, and real-time data acquisition systems where deterministic latency and depth expansion are required.

For engineers reviewing the CY7C4251-15AC datasheet, CY7C4251-15AC pinout, CY7C4251-15AC application, or CY7C4251-15AC equivalent, key selection criteria include its 8K-depth buffering capability, 100 MHz clock support, programmable flag offsets, center-power-pin noise reduction, and width/depth expansion architecture.

Technical Context

The CY7C4251-15AC implements a dual-port SRAM-based FIFO with independent RCLK and WCLK domains, enabling true asynchronous read/write operation. Its control logic includes synchronized EF/FF flags (RCLK- and WCLK-locked respectively) and programmable PAE/PAF flags updated via dedicated offset registers accessed through WEN2/LD pin configuration.

Flag programming uses a four-cycle WCLK sequence to load empty/full offset values into 8-bit LSB/MSB registers; default offsets are 007h (7 words), supporting single-word granularity adjustment. The device resets to empty state on RS assertion, with all outputs driven low after tRSF, and supports three-state output control via OE.

Key Specifications

Pinout & Package

32-pin Thin Quad Flat Package (TQFP), 7 mm × 7 mm body, 0.5 mm pitch, lead-free compliant. Pin 1 marked by corner notch; center VCC (Pin 16) and GND (Pin 17) minimize power delivery impedance and ground bounce.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT72251L15PF and MC100EP51M, the CY7C4251-15AC offers superior integration for industrial and embedded systems via its programmable flags, center-power noise reduction, and unified WEN2/LD configuration - reducing BOM count and layout complexity without sacrificing timing margin.

Availability

CY7C4251-15AC is available at Aetrix Electronics and suitable for industrial data acquisition, multi-processor interconnect, and serial communication bridge applications requiring stable component supply across extended product lifecycles.

Supply support for CY7C4251-15AC 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, designs high-performance memory and programmable logic solutions for industrial, automotive, and IoT applications.

The CY7C42X1 FIFO family targets deterministic data buffering in mixed-clock-domain systems, emphasizing low-latency flag response, expandability, and noise-immune packaging for mission-critical embedded interfaces.

FAQ

What is the default Almost Empty offset value for CY7C4251-15AC?

The default Almost Empty offset is 007h (7 decimal words), stored in the empty offset LSB register. This value is factory-programmed and applies unless overwritten via the WEN2/LD flag programming sequence. The offset determines the FIFO word count threshold at which the PAE flag asserts LOW, and remains valid across power cycles without reprogramming.

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

Yes, RCLK and WCLK may be connected to the same clock source for synchronous operation. In this configuration, the device behaves as a clocked FIFO with unified timing, retaining all status flags and OE functionality. However, EF/FF flags remain synchronized to their native clocks - EF to RCLK and FF to WCLK - so both signals must be active and stable for correct flag behavior.

How does the CY7C4251-15AC handle underflow during read operations?

When the FIFO is empty and additional read cycles occur, the Q0–Q8 outputs retain the last valid data word rather than entering undefined states. This behavior is hardware-enforced and eliminates the need for external logic to mask invalid reads. The EF flag remains LOW to indicate emptiness, and no underflow error is generated - simplifying host controller firmware.

Is CY7C4251-15AC RoHS-compliant and lead-free?

Yes, the CY7C4251-15AC is manufactured in Pb-free (lead-free) packages per JEDEC J-STD-609, with matte tin finish and compliant with RoHS Directive 2011/65/EU. The TQFP package uses SnAgCu solder alloy and meets IPC/JEDEC J-STD-020 moisture sensitivity level 3 (MSL3) requirements for standard surface-mount assembly.