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W164 Datasheet, PDF (1/11 Pages) Cypress Semiconductor – Spread Spectrum Desktop/Notebook System Frequency Generator
W164
Spread Spectrum Desktop/Notebook System
Frequency Generator
Features
Key Specifications
• Maximized EMI suppression using Cypress’s Spread
Spectrum technology
• Reduces measured EMI by as much as 10 dB
• I2C 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
Supply Voltages:....................................... VDDQ3 = 3.3V±5%
VDDQ2 = 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-kΩ 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#
CPU(0:1)
1
100 MHz
0
66.8 MHz
PCI
33.3 MHz
33.4 MHz
Block Diagram
X1
XTAL
X2
OSC
PLL Ref Freq
VDDQ3
REF2X/SEL48#
GND
VDDQ3
IOAPIC
VDDQ2
CPU0
CPU1
GND
Pin Configuration
X1 1
X2 2
GND 3
PCI_F 4
PCI1 5
PCI2 6
PCI3 7
PCI4 8
VDDQ3 9
PCI5 10
PCI6 11
VDDQ3 12
48MHz 13
24/48MHz 14
28 GND
27 REF2X/SEL48#
26 VDDQ3
25 VDDQ2
24 IOAPIC
23 VDDQ2
22 CPU0
21 CPU1
20 VDDQ3
19 GND
18 SDATA
17 SCLOCK
16 SEL100/66#
15 GND
100/66#_SEL
PLL 1
÷2/÷3/÷4
SDATA
SCLOCK
I2C
LOGIC
VDDQ3
PCI_F
PCI1
PCI2
PCI3
PCI4
PCI5
PCI6
GND
PLL2
VDDQ3
48MHz
24/48MHz
GND
Cypress Semiconductor Corporation • 3901 North First Street • San Jose • CA 95134 • 408-943-2600
December 16, 1999, rev. **
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