CY28RS400ZXC

Application Specific Clock/Timing Overview

The CY28RS400ZXC is a clock generator IC designed for the ATI RS400 chipset, supporting Intel CPU architectures. It features two internal PLL circuits and generates differential CPU clock pairs, 100-MHz differential SRC clocks, a 48-MHz USB clock, and a 33-MHz PCI clock. The device operates with a 3.3V supply (3.135V to 3.465V) and supports frequencies up to 266MHz. It utilizes LVTTL or crystal inputs and provides outputs in a 56-pin TFSOP/TSSOP package. Key features include selectable CPU frequencies via hardware straps, I2C support for configuration, and spread spectrum capabilities for EMI reduction.

Application Specific Clock/Timing Feature Summary

• Supports Intel CPU with selectable frequencies (100/133/200/266 MHz) via FS_A/B/C pins
• Generates differential CPU, 100-MHz SRC, 48-MHz USB, and 33-MHz PCI clocks
• Includes I2C interface for register configuration and readback capabilities
• Features Lexmark Spread Spectrum profile for maximum EMI reduction

Application Specific Clock/Timing Applications

• ATI RS400 Chipset systems
• Intel-based motherboard designs
• CPU clock generation for desktop platforms

Application Specific Clock/Timing Procurement Notes

Verify component status as this model may be discontinued. Confirm package type availability (56-TSSOP II) and ensure compatibility with existing PCB footprints. Check for RoHS compliance status if required by current manufacturing standards. Review datasheet revision history for any pinout or electrical specification changes compared to legacy inventory.

Application Specific Clock/Timing Selection Notes

Select this component specifically for ATI RS400 chipset applications requiring Intel CPU clock support. Ensure the design accommodates the 56-pin SSOP/TSSOP package dimensions. Verify that the system power supply strictly adheres to the 3.3V ±5% range. Consider the need for external parallel resonance crystals with appropriate load capacitance calculations to meet ppm specifications.

Application Specific Clock/Timing Part Context

Manufactured by Infineon Technologies (formerly Cypress Semiconductor), the CY28RS400 series belongs to the application-specific clock timing category. It is part of a family of clock generators optimized for specific chipset requirements, particularly those involving Intel processors and ATI graphics chipsets during the mid-2000s era of PC architecture.

Application Specific Clock/Timing Replacement Considerations

No public confirmed substitute part numbers are available in the provided documentation. Due to the specific integration with the ATI RS400 chipset and Intel frequency tables, direct pin-to-pin replacements may require schematic verification.