W83195R-08
150MHZ 4-DIMM CLOCK
1.0 GENERAL DESCRIPTION
The W83195R-08 is a Clock Synthesizer which provides all clocks required for high-speed RISC or
CISC microprocessor such as Intel Pentium II. W83195R-08 provides sixteen CPU/PCI frequencies
which are externally selectable with smooth transitions. W83195R-08 also provides 17 SDRAM clocks
controlled by the none-delay buffer_in pin.
The W83195R-08 accepts a 14.318 MHz reference crystal as its input and runs on a 3.3V supply.
Spread spectrum built in at ¡Ó0.5% or ¡Ó0.25% to reduce EMI. Programmable stopping individual
clock outputs and frequency selection through I2C interface. The device meets the Pentium power-up
stabilization, which requires CPU and PCI clocks be stable within 2 ms after power-up. Using dual
function pin for the slots(ISA, PCI, CPU, DIMM) is not recommend. The add on cards may have a
pull up or pull down.
High drive seven PCI and SDRAM CLOCK outputs typically provide greater than 1 V /ns slew rate
into 30 pF loads. Two CPU CLOCK outputs typically provide better than 1 V /ns slew rate into 20 pF
loads, when maintaining 50¡Ó 5% duty cycle. The fixed frequency outputs, such as REF, 24MHz and
48 MHz provide better than 0.5V /ns slew rate.
2.0 PRODUCT FEATURES
• Supports Pentium™ II CPU with I2C.
• 3 CPU clocks (one free-running CPU clock)
• 17 SDRAM clocks for 4 DIMs
• 7 PCI synchronous clocks
• Two IOAPIC clocks for multiprocessor support
• Optional single or mixed supply:
(Vddq1=Vddq2 = Vddq3 = Vddq4 = VddL1 =VddL2= 3.3V) or (Vddq1= Vddq2 = Vddq3=Vddq4 =
3.3V, VddL1 = VdqL2 = 2.5V)
• < 250ps skew among CPU and SDRAM clocks
• < 250ps skew among PCI clocks
• < 5ns propagation delay SDRAM from buffer input
• Skew from CPU(earlier) to PCI clock -1 to 4ns, center 2.6ns.
• Smooth frequency switch with selections from 50 MHz to 133 MHz CPU
• I2C 2-Wire serial interface and I2C read back
• ¡Ó0.25% or ¡Ó0.5% center type spread spectrum function to reduce EMI
• Programmable registers to enable/stop each output and select modes
(mode as Tri-state or Normal )
• MODE pin for power Management
• One 48 MHz for USB & one 24 MHz for super I/O
• 56-pin SSOP package
Publication Release Date: Mar. 1999
-1-
Revision 0.30