GENERAL DESCRIPTION

The W83194R-39/-39A is a Clock Synthesizer which provides all clocks required for high-speed RISC or CISC microprocessor such as Intel Pentium II. W83194R-39 provides eight different frequency of CPU and PCI clocks and W83194R-39A provides sixteen CPU/PCI frequencies which are externally selectable with smooth transitions. W83194R-39/-39A also provides 13 SDRAM clocks controlled by the none-delay buffer_in pin.

The W83194R-39/-39A 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. It is not recommend to use the dual function pin for the slots(ISA, PCI, CPU, DIMM). The add on cards may have a pull up or pull down.

PRODUCT FEATURES

· Supports PentiumÔ II CPU with I2C.

· 2 CPU clocks (one free-running CPU clock)

· 13 SDRAM clocks for 3 DIMs

· 6 PCI synchronous clocks

· One IOAPIC clock 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