W196
Spread Spectrum FTG for 440BX and VIA Apollo Pro-133
1W196
Features
• Maximized EMI suppression using Cypress’s Spread
Spectrum Technology
• System frequency synthesizer for 440BX, 440ZX, and
VIA Apollo Pro-133
• I
2
C programmable to 155 MHz (32 selectable
frequencies)
• Two skew-controlled copies of CPU output
• 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 clock 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
...............................................................................................
V
DDQ2
= 2.5V±5%
CPU Cycle to Cycle Jitter: ......................................... 250 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: ........................1.5 to 4.0 ns (CPU Leads)
REF2X/SEL48#, SCLOCK, SDATA: ...............250-k pull-up
FS1: ........................................................... 250-k
pull-down
FS0: .................................................. No pull-up or pull-down
Note:
Internal pull-up or pull-down resistors should not be
relied upon for setting I/O pins HIGH or LOW.
Table 1. Pin Selectable Frequency
FS1
1
1
0
0
FS0
1
0
1
0
CPU(0:1)
133.3 MHz
105 MHz
100 MHz
66.8 MHz
PCI
33.3 MHz
35 MHz
33.3 MHz
33.3 MHz
Key Specifications
Supply Voltages:........................................V
DDQ3
= 3.3V±5%
Rev 1.0, November 28, 2006
2200 Laurelwood Road, Santa Clara, CA 95054
Tel:(408) 855-0555
Fax:(408) 855-0550
Page 1 of 11
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