器件名称: W149
功能描述: 440BX AGPset Spread Spectrum Frequency Synthesizer
文件大小: 158.53KB 共16页
简 介: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 SMBus 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
PLL Ref Freq
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