Infineon Technologies CY7C4251V-25AXC

Overview

CY7C4251V-25AXC from Cypress Semiconductor is an 8K × 9-bit synchronous FIFO memory with 3.3 V operation, 66 MHz maximum clock frequency (25 ns cycle time), programmable Almost Empty/Almost Full flags, and 5 V-tolerant inputs. It serves as a high-speed data buffer in multi-processor interconnects and serial protocol bridging where depth and deterministic latency are critical.

For engineers reviewing the CY7C4251V-25AXC datasheet, CY7C4251V-25AXC pinout, CY7C4251V-25AXC application, or CY7C4251V-25AXC equivalent, key selection criteria include synchronous dual-clock operation, programmable flag offsets, 9-bit bus width, TQFP-32 package compatibility, and 3.3 V / 5 V I/O tolerance for mixed-voltage system integration.

Technical Context

The CY7C4251V-25AXC implements a dual-port SRAM-based FIFO architecture with independent read (RCLK) and write (WCLK) clocks, each supporting up to 66 MHz operation. Its status flags-EF, FF, PAE, PAF-are fully synchronous: EF and PAE update on RCLK edges; FF and PAF update on WCLK edges.

Flag thresholds are programmable via four 8-bit offset registers accessed through WEN2/LD in load mode. Default empty/full offsets are 7 words; depth-specific arithmetic applies (e.g., PAF asserts when unread words ≥ 8192 − m). The device uses 0.65 µm CMOS with >2001 V HBM ESD protection and guard-ring latch-up prevention.

Key Specifications

Pinout & Package

32-pin TQFP (7 mm × 7 mm), RoHS-compliant, with center power (Pin 17) and ground (Pin 16) pins for improved signal integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT72V2115L15PF and SN74V293-25PAG, the CY7C4251V-25AXC uniquely balances deep 8K × 9 storage, single-word programmable flags, 5 V-tolerant I/O, and TQFP packaging - making it optimal for cost-sensitive industrial bridges requiring flexible flow control without external level shifters or parity logic.

Availability

CY7C4251V-25AXC is available at Aetrix Electronics and suitable for high-speed data acquisition systems, multi-processor interconnects, serial protocol bridging, and industrial Ethernet node buffering requiring stable component supply and long-term obsolescence management.

Supply support for CY7C4251V-25AXC 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 memory, microcontrollers, and programmable logic solutions for industrial, automotive, and communications markets.

The CY7C42X1V product line was designed specifically for high-reliability, low-latency data buffering in mixed-voltage, multi-clock-domain embedded systems - emphasizing deterministic timing, noise immunity, and seamless voltage translation.

FAQ

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

The CY7C4251V-25AXC requires a minimum RS pulse width of 10 ns to guarantee proper reset to the empty state. This ensures all internal pointers and flag registers initialize correctly before first access. The device enters a known state only after RS returns HIGH and tRSF (15 ns) elapses - during which Q0–Q8 remain LOW and EF goes LOW.

Can RCLK and WCLK be operated at different frequencies, and what are the limits?

Yes - RCLK and WCLK may run independently at any frequency up to 66 MHz each. No phase relationship is required. However, sustained write rates exceeding read rates will eventually assert FF; sustained reads beyond writes will assert EF. The FIFO does not throttle clocks - flow control must be managed externally via flag monitoring.

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

The Almost Empty threshold is set by writing to the 8-bit Empty Offset LSB and MSB registers via WEN2/LD in load mode. Default value is 007h (7 decimal), meaning PAE asserts when ≤7 words remain unread. Programming occurs over four consecutive WCLK edges with WEN1 and WEN2/LD both LOW, starting with LSB.

Is the CY7C4251V-25AXC pin-compatible with other members of the CY7C42X1V family?

No - all CY7C42X1V variants (e.g., CY7C4231V, CY7C4241V) share identical pinouts and electrical characteristics within the same speed grade and package type. CY7C4251V-25AXC is functionally and physically compatible with CY7C4241V-25AXC and CY7C4231V-25AXC in TQFP-32, differing only in memory depth (8K vs. 4K vs. 2K).