W254B Datasheet, PDF (6/16 Pages) SpectraLinear Inc – 133MHz Spread Spectrum FTG for Mobile Pentium® III Platforms

W254B
0 ns
CPU 133-MHz
SDRAM 133-MHz
3V66 66-MHz
PCI 33-MHz
APIC33-MHz
REF 14.318-MHz
USB 48-MHz
DOT 48-MHz
10 ns
Cycle Repeats
20 ns
30 ns
40 ns
Figure 5. Group Offset Waveforms (133-MHz CPU/133-MHz SDRAM Clock)
Table 8. 133 MHz/SDRAM Test Mode Group Timing Relationships and Tolerance
Offset
CPU to SDRAM
3.75 ns
CPU to 3V66
0.0 ns
SDRAM to
3V66 3V66 to PCI PCI to APIC USB& DOT
3.75 ns 1.5-3.5 ns 0.0 ns
Async
Tolerance
500 ps
500 ps
500 ps
500 ps
1.0 ns
N/A
Power-Down Control
W254B provides one PWR_DWN# signal to place the device in low-power mode. In low-power mode, the PLLs are turned off
and all clock outputs are driven LOW.
0 ns
25 ns
50 ns
VCO Internal
CPU 100-MHz
3V66 66-MHz
PCI 33 MHz
APIC 33-MHz
PwrDwn
SDRAM 100-MHz
REF 14.318-MHz
USB 48-MHz
1
2
Figure 6. W254B PWR_DWN# Timing Diagram^{[4, 5, 6, 7]}
75 ns
Center
Rev 1.0, November 20, 2006
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