CDC9449
PC CLOCK SYNTHESIZER/DRIVER
WITH SDRAM CLOCK SUPPORT

SCAS577 - AUGUST 1996

features

• Utility Clock Generation for Personal Computer Applications
• Two 48-MHz Serial Bus Clock Outputs
• One 24-MHz Super I/O Controller Clock Output
• One AUDIO Clock Output With Selectable Frequency
• One Clock Output at 1/2 AUDIO Clock Frequency
• All Output Clock Frequencies Derived From a Single 14.31818-MHz Crystal Input
• Internal Loop Filters for Phase-Lock Loops (PLL)
• Packaged in Shrink Small-Outline Package

description

The CDC9449 is a system clock synthesizer for use in personal computer systems. An integrated crystal oscillator generates a 14.318-MHz reference frequency, while two integrated PLLs generate a 48-MHz clock, a 24-MHz clock, and a selectable AUDIO and 1/2 AUDIO clock frequency from a 14.31818-MHz crystal input.

The CDC9449 provides two copies of the 48-MHz serial bus clock, one copy of the 24-MHz super I/O controller clock, one copy of the AUDIO clock, one copy of the 1/2 AUDIO clock, and three copies of the 14.318-MHz reference frequency.

All outputs are 3-state and can be disabled by the output-enable (OE) control input. When OE = L, all outputs are placed in a high-impedance state.

The CDC9449 is characterized for operation from 0°C to 70°C.