W164
Spread Spectrum Desktop/Notebook System Frequency Generator
Features
• Maximized EMI suppression using Cypress’s Spread
Spectrum technology
• Reduces measured EMI by as much as 10 dB
• I
2
C programmable to 153 MHz (16 selectable
frequencies)
• Two skew-controlled copies of CPU output
• SEL100/66# selects CPU frequency (100 or 66.8 MHz)
• Seven copies of PCI output (synchronous w/CPU
output)
• One copy of 14.31818-MHz IOAPIC output
• One copy of 48-MHz USB output
• Selectable 24-/48-MHz output is determined by resistor
straps on power-up
• One high-drive output buffer that produces a copy of
the 14.318-MHz reference
• Isolated core VDD pin for noise reduction
Key Specifications
Supply Voltages: ....................................... V
DDQ3
= 3.3V±5%
...............................................................................................
V
DDQ2
= 2.5V±5%
CPU Cycle to Cycle Jitter: .......................................... 200 ps
CPU, PCI Output Edge Rate:
1 V/ns
CPU0:1 Output Skew: ................................................ 175 ps
PCI_F, PCI1:6 Output Skew: ...................................... 500 ps
CPU to PCI Skew: ..............................1 to 4 ns (CPU Leads)
REF2X/SEL48#, SCLOCK, SDATA ................250-k
pull-up
Note:
Internal pull-up resistors should not be relied upon for
setting I/O pins HIGH.
Table 1. Pin Selectable Frequency
SEL100/66#
1
0
CPU(0:1)
100 MHz
66.8 MHz
PCI
33.3 MHz
33.4 MHz
Rev 1.0, November 28, 2006
2200 Laurelwood Road, Santa Clara, CA 95054
Tel:(408) 855-0555
Fax:(408) 855-0550
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SPECTRALINEAR [ SPECTRALINEAR INC ]
