W83195R-08

150MHZ 4-DIMM CLOCK

Publication Release Date: Mar. 1999

- 1 -

Revision 0.30

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 I

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

• 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

•

I

• ¡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