Infineon Technologies CY28RS480ZXC

Overview

CY28RS480ZXC from Cypress Semiconductor is a dedicated clock generator IC for the AMD ATI RS480 chipset, providing synchronized differential and single-ended clock outputs including 200-MHz CPU clocks, 100-MHz SRC clocks, 48-MHz USB, 33-MHz PCI, and 66-MHz HyperTransport™ clocks. It integrates I²C programmability, spread-spectrum control, and multi-rail 3.3V power domains for AMD K8 platform timing.

For engineers reviewing the CY28RS480ZXC datasheet, CY28RS480ZXC pinout, CY28RS480ZXC application, or CY28RS480ZXC equivalent, key selection criteria include differential output compliance (Intel Type-X/Type-5/Type-3A), I²C register-level output enable/disable control, spread-spectrum EMI reduction settings, and per-output power domain isolation (VDD_CPU, VDD_SRC, VDD_PCI, etc.).

Technical Context

The CY28RS480ZXC uses a dual-PLL architecture: one PLL locks to the 14.318-MHz crystal input (XIN/XOUT) to generate the REF clock and feed the CPU/HTT/PCI dividers; the second PLL synthesizes the 100-MHz SRC clocks with selectable spread-spectrum modulation (–0.35% or –0.50%). All clock outputs are independently enabled/disabled via I²C-accessible control registers.

It supports Minicard-compliant CLKREQ#0/CLKREQ#1 asynchronous stop/start control for SRC outputs, with debounced recognition requiring two consecutive DIFC rising edges. Output drive strength (e.g., HTT66 high/low drive, USB_48 1x/2x) and tri-state behavior during power-down or stop are configurable per register bit.

Key Specifications

Pinout & Package

56-pin SSOP/TSSOP package with 0.5-mm pitch; thermally enhanced layout supporting separate analog (VDDA/VSSA), CPU (VDD_CPU/VSS_CPU), SRC (VDD_SRC/VSS_SRC), PCI (VDD_PCI/VSS_PCI), REF (VDD_REF/VSS_REF), HTT (VDD_HTT/VSS_HTT), USB (VDD_48/VSS_48), and SRCS (VDD_SRCS/VSS_SRCS) power domains.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar clock generator applications.

Compared with ICS954202AGLFT and ICS952601AGT, the CY28RS480ZXC uniquely delivers full AMD RS480 timing coverage-including synchronized 200-MHz CPU, 100-MHz SRC, 66-MHz HTT, and triple REF clocks-with I²C configurability and per-rail power management essential for platform-level compliance.

Availability

CY28RS480ZXC is available at Aetrix Electronics and suitable for AMD-based motherboards, PCI Express Mini-Cards, embedded industrial PCs, and legacy PCI/AGP systems requiring stable component supply and long-term lifecycle support.

Supply support for CY28RS480ZXC 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 timing, memory, and programmable logic solutions for computing and communications platforms.

The CY28RS480 belongs to Cypress's AMD chipset-specific clock generator product line, engineered to meet the precise frequency, skew, and spread-spectrum requirements of the ATI RS480 platform.

FAQ

What crystal specifications are required for reliable CY28RS480ZXC operation?

The CY28RS480ZXC requires a 14.31818-MHz parallel-resonant AT-cut crystal with 20-pF load capacitance, ≤35-ppm initial tolerance, ≤30-ppm temperature stability, and ≤5-ppm aging. Substituting a series-resonant crystal causes ≥300-ppm frequency error and violates timing specifications.

How does the CLKREQ#0/CLKREQ#1 interface interact with I²C register control?

CLKREQ#0/CLKREQ#1 provide hardware-level asynchronous stop/start of SRC outputs mapped in Registers Bytes 4–5; I²C retains full control over enable/disable, drive strength, and spread-spectrum settings. The two mechanisms operate independently-CLKREQ# overrides I²C state only during assertion.

Can the CY28RS480ZXC generate non-standard frequencies like 133-MHz or 166-MHz?

No-the CY28RS480ZXC is hardwired to generate only its specified frequencies: 200-MHz (CPU), 100-MHz (SRC), 66-MHz (HTT), 48-MHz (USB), 33-MHz (PCI), and 14.318-MHz (REF). It lacks fractional-N PLL or programmable divider ratios for custom frequencies.

Is spread-spectrum modulation applied to all clock outputs?

No-spread-spectrum modulation is configurable only for CPU and SRC clocks via Register Byte 2 bit 2. USB_48, PCI0, HTT66, and REF[2:0] outputs remain fixed-frequency to preserve timing-critical interfaces like USB 2.0 and PCI signaling integrity.