W83194R-81 Datasheet, PDF (1/18 Pages) Winbond – 100MHZ CLOCK FOR SIS CHIPSET

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