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W83194BR-648

CLOCK GENERATOR FOR SIS P4 SERIES CHIPSET

Winbond 

W83194BR-648

1. GENERAL DESCRIPTION

The W83194BR-648 is a Clock Synthesizer for SIS P4 series chipset. W83194BR-648 provides all

clocks required for high-speed Intel Pentium 4, and also provides 32 different frequencies of CPU

clocks frequency setting. All clocks are externally selectable with smooth transitions. The W83194BR-

648 makes SDRAM in synchronous or asynchronous frequency with CPU clocks.

The W83194BR-648 provides step-less frequency programming by controlling the VCO freq. and the

programmable AGP, PCI clock output divisor ratio. AGP and PCI frequency can be fixed to be four

kinds of different frequency outputs. A watchdog timer is quipped and when time out, register9 bit5 will

be set to 1 for warning. Spread spectrum built in at ±0.5% or ±0.25% to reduce EMI. Programmable

stopping individual clock outputs and frequency selection through I2C interface.

The W83194BR-648 accepts a 14.318 MHz reference crystal as its input and runs on a 3.3V supply.

High drive PCI CLOCK outputs typically provide greater than 1V /nS slew rate into 30 pF loads. The

fixed frequency outputs as REF, 24 MHz, and 48 MHz provide better than 0.5V /nS slew rate.

2. FEATURES

• Supports Intel Pentium 4 CPU with I2C.

• 2 pairs of differential CPU clocks

• 2 ZCLK for SIS chipsets

• 2 AGP clocks

• 1 SDRAM output clock for chipset

• 8 PCI synchronous clocks

• 1 24/48 MHz, 1 48 MHz

• 3 REF clocks

• Skew --- CPU to SDRAM < 1 ns, PCI to PCI < 500ps, AGP to AGP < 175ps

• Smooth frequency switch with selections from 66 to 200 MHz

• I2C 2-Wire serial interface and I2C read back

• Flexible spread spectrum to reduce EMI

• Programmable registers to enable/stop each output

• Packaged in 48-pin SSOP

Publication Release Date: April 13, 2005

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Revision 1.1

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