W149

W149 440BX AGPset Spread Spectrum Frequency Synthesizer Features Maximized EMI suppression using Cypress’s Spread Spectrum Technology Single chip system frequency synthesizer for Intel® 440BX AGPset Two copies of CPU output Six copies of PCI output One 48-MHz output for USB One 24-MHz output for SIO Two buffered reference outputs One IOAPIC output Thirteen SDRAM outputs provide support for 3 DIMMs Spread Spectrum feature always enabled I2C™ interface for programming Power management control inputs Smooth CPU frequency switching from 66.8–124 MHz VDDQ3: ..................................................................... 3.3V±5% VDDQ2: ..................................................................... 2.5V±5% SDRAMIN to SDRAM0:12 Delay:.......................... 3.7 ns typ. Table 1. Mode Input Table[1] Mode 0 1 Table 2. Pin Selectable Frequency Input Address FS2 1 1 1 1 0 0 0 0 FS1 1 1 0 0 1 1 0 0 FS0 1 0 1 0 1 0 1 0 [2] Pin 2 PCI_STOP# REF0 CPU0:1 (MHz) 100 100 103 66.8 83.3 66.8 124 PCI_F, 1:5 (MHz) 33.3 (CPU/3) (Reserved) 33.3 (CPU/3) 34.3 (CPU/3) 33.4 (CPU/2) 41.7 (CPU/2) 33.4 (CPU/2) 41.3 (CPU/3) Spread % –0.5 ±0.5 –0.5 –0.5 –0.5 ±0.5 –0.5 Key Specifications CPU Cycle-to-Cycle Jitter: ......................................... 250 ps CPU to CPU Output Skew: ........................................ 175 ps PCI to PCI Output Skew: ............................................ 500 ps Logic Block Diagram VDDQ3 REF0/(PCI_STOP#) X1 X2 XTAL OSC ...