133MHz Clock Synthesizer/Driver for PC Motherboards with 3-State Outputs 48-SSOP
description
The CDC921 is a clock synthesizer/driver that generates CPU, CPU_DIV2, 3V66, PCI, APIC, 48MHz, and REF
system clock signals to support computer systems with a single Pentium III class microprocessor.
All output frequencies are generated from a 14.318-MHz crystal input. Instead of a crystal, a reference clock input can be provided at the XIN input. Two phase-locked loops PLLs are used to generate the host frequencies and the 48-MHz clock frequency. On-chip loop filters and internal feedback eliminate the need for external components.
Generates Clocks for Pentium III Class Microprocessors
Supports a Single Pentium III Microprocessor
Uses a 14.318 MHz Crystal Input to Generate Multiple Output Frequencies
Includes Spread Spectrum Clocking SSC, 0.5% Downspread for Reduced EMI Performance
Power Management Control Terminals
Low Output Skew and Jitter for Clock Distribution
Operates from Dual 2.5-V and 3.3-V Supplies
Generates the Following Clocks:
– 3 CPU 2.5 V, 100/133 MHz
– 10 PCI 3.3 V, 33.3 MHz
– 1 CPU/2 2.5 V, 50/66 MHz
– 1 APIC 2.5 V, 16.67 MHz
– 3 3V66 3.3 V, 66 MHz
– 2 REF 3.3 V, 14.318 MHz
– 1 48MHz 3.3 V, 48 MHz
Packaged in 48-Pin SSOP Package
Designed for Use with ’s Direct Rambus Clock Generators CDCR81, CDCR82, CDCR83