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W83194R-81

100MHZ CLOCK FOR SIS CHIPSET

Winbond 

W83194R-81

100MHZ CLOCK FOR SIS CHIPSET

1.0 GENERAL DESCRIPTION

The W83194R-81 is a Clock Synthesizer for SiS chipset. W83194R-81 provides all clocks required

for high-speed RISC or CISC microprocessor such as AMD,Cyrix,Intel Pentium and also provides 16

different frequencies of CPU clocks frequency setting. All clocks are externally selectable with

smooth transitions. The W83194R-81 makes SDRAM in synchronous or asynchronous frequency

with CPU clocks.

The W83194R-81 provides I2C serial bus interface to program the registers to enable or disable each

clock outputs and W83194R-81 provides the 0.25%, 0.5% center type spread spectrum to reduce

EMI.

The W83194R-81 accepts a 14.318 MHz reference crystal as its input and runs on a 3.3V supply.

High drive PCI and SDRAM CLOCK outputs typically provide greater than 1 V /ns slew rate into 30

pF loads. CPU CLOCK outputs typically provide better than 1 V /ns slew rate into 20 pF loads as

maintaining 50¡Ó 5% duty cycle. The fixed frequency outputs as REF, 24MHz, and 48 MHz provide

better than 0.5V /ns slew rate.

2.0 PRODUCT FEATURES

• Supports Pentium™, Pentium™ Pro, AMD and Cyrix CPUs with I2C.

• 3 CPU clocks

• 13 SDRAM clocks for 3 DIMMs

• 6 PCI synchronous clocks.

• Optional single or mixed supply:

(Vdd = Vddq4=Vddq3 = Vddq2b = 3.3V, Vddq2=2.5V) or

(Vdd = Vddq4=Vddq3 = 3.3V, Vddq2=Vdq2b = 2.5V)

• Skew form CPU to PCI clock -1 to 4 ns, center 2.6 ns

• SDRAM frequency synchronous or asynchronous to CPU clocks

• Smooth frequency switch with selections from 66 to 133mhz(including 90MHz)

• I2C 2-Wire serial interface and I2C read back

• 0.25%, 0.5% center type spread spectrum to reduce EMI

• Programmable registers to enable/stop each output and select modes

(mode as Tri-state or Normal )

• MODE pin for power Management

• 48 MHz for USB

• 24 MHz for super I/O

• 48-pin SSOP package

Publication Release Date: Dec. 1998

-1-

Revision 0.20

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