Infineon Technologies CY7C425-20JXC

Overview

CY7C425-20JXC from Cypress Semiconductor is a 1K × 9-bit asynchronous FIFO memory with dual-port RAM architecture, supporting independent 50 MHz read/write operations, TTL-compatible I/O, and integrated Empty/Full/Half-Flat flags - used in high-speed data buffering between mismatched clock domains in industrial communication gateways.

For engineers reviewing the CY7C425-20JXC datasheet, CY7C425-20JXC pinout, CY7C425-20JXC application, or CY7C425-20JXC equivalent, key selection criteria include its 1024-word depth, 9-bit width, 20 ns access time, standalone retransmit capability, and PLCC-28 package compatibility with legacy board layouts.

Technical Context

This FIFO implements asynchronous dual-clock operation using separate read (R) and write (W) control lines, with flag logic generating EF (Empty), FF (Full), and XO/HF (Expansion Out / Half Full) outputs. The device uses a 0.65-µm P-well CMOS process and supports width expansion via D0–D8 and Q0–Q8 bus steering, plus depth expansion using MR (Master Reset) and XO signals.

Retransmit functionality is activated by pulling FL/RT low while holding R and W high, enabling deterministic replay of buffered data without external sequencing logic. All I/Os are TTL-compatible with VOH ≥ 2.4 V at IOH = –2.0 mA and VOL ≤ 0.4 V at IOL = 8.0 mA, ensuring interoperability with 5V logic families.

Key Specifications

Pinout & Package

Package: 28-pin Plastic Leaded Chip Carrier (PLCC), 11.43 mm × 11.43 mm, JEDEC MS-026AC, lead-free compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT7202L20PFI and AM7202-20JC, CY7C425-20JXC uniquely delivers full 1K × 9 buffering in PLCC-28 with integrated retransmit and Half-Flat flag - making it optimal for protocol-aware buffering where deterministic replay and depth-expansion readiness are required.

Availability

CY7C425-20JXC is available at Aetrix Electronics and suitable for industrial serial gateways, legacy bus bridges, protocol analyzers, and real-time signal loggers requiring stable component supply and long-term obsolescence management.

Supply support for CY7C425-20JXC 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-reliability interface and memory ICs for industrial, automotive, and communications systems, with emphasis on interoperability and longevity.

The CY7C4xx FIFO family targets deterministic data buffering in mixed-clock-domain systems - specifically engineered to replace discrete logic-based queue implementations with single-chip solutions offering guaranteed timing and expandability.

FAQ

What is the maximum operating temperature range for CY7C425-20JXC?

The CY7C425-20JXC is rated for industrial temperature operation from –40°C to +85°C, with V_CC = 5.0 V ±10%. It also supports commercial (0°C to +70°C) and military (–55°C to +125°C) grades in other suffix variants, but the JXC suffix explicitly denotes the industrial-grade version with validated performance across this full range.

Does CY7C425-20JXC require external pull-up resistors on EF and FF pins?

Yes - EF and FF are open-drain outputs and require external 4.7 kΩ pull-up resistors to V_CC to assert HIGH when inactive. This is mandatory per the datasheet's DC electrical characteristics and ensures correct flag polarity (EF = HIGH when empty, FF = HIGH when full) in system-level logic interfacing.

Can CY7C425-20JXC be used in depth-expansion mode with different speed grades?

No - all devices in a depth-expanded chain must share identical speed grades (e.g., all –20 variants) to maintain synchronized flag propagation and avoid metastability. Mixing –20 and –25 devices violates tXOL/tXOH timing margins and risks incorrect EF/FF assertion due to skew in expansion-out signal delays.

Is the retransmit function available in width-expanded configurations?

Yes - retransmit remains fully functional in width-expanded setups (e.g., two CY7C425s for 18-bit data). Both devices respond simultaneously to FL/RT assertion, provided their R and W inputs are tied together and driven high during retransmit - preserving bit-aligned replay across the widened bus.