W207B
Spread Spectrum FTG for SiS540 and 630 Chipsets
Features
Table 1. Pin Selectable Frequency
CPU SDRAM
PC
• Maximized EMI Suppression using Cypress’s Spread
Spectrum technology
FS3 FS2 FS1 FS0 (MHz) (MHz) (MHz)
SS
• Single-chip system frequency synthesizer for SiS540
and SiS630 core logic chip sets
• Three copies of CPU output
• Seven copies of PCI output
• One 48-MHz output for USB
• One 24-/48-MHz selectable output for SIO
• Two buffered reference outputs
• 14 SDRAM outputs provide supportfor 3DIMMs SMBus
interface for programming
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
66.6
100.2
150.3
133.6
66.8
100.0
100.2
100.2
100.2
111.3
133.6
150.3
133.3
66.6
33.3
–0.6%
33.4 ±0.45%
37.6 OFF
33.4 ±0.45%
33.4 OFF
33.4 ±0.45%
100.2
100.2
133.3
66.6
33.4
33.3
33.3
31.2
32.3
OFF
–0.6%
–0.6%
OFF
Key Specifications
83.3
83.3
CPU Cycle-to-Cycle Jitter: ......................................... 250 ps
CPU to CPU Output Skew: ........................................ 175 ps
PCI to PCI Output Skew: ............................................ 500 ps
CPU to PCI Output Skew (CPU leads): ................... 1 to 4 ns
CPU to SDRAM Output Skew:.................................... 500 ps
97.0
97.0
–0.6%
95.0
95.0
31.7 ±0.45%
95.0
126.7
112.0
91.5
31.7
37.3
30.5
30.5
OFF
OFF
112.0
122.0
122.0
–0.6%
–0.6%
122.0
V
V
: .................................................................... 3.3V±5%
: .................................................3.3V±5% or 2.5V±5%
DDQ3
DDQ2
Pin Configuration[1]
Block Diagram
VDDQ3
REF1
VDDQ2
CPU0
CPU1
GND
CPU2
VDDQ3
SDRAM13
SDRAM12
GND
SDRAM11
SDRAM10
VDDQ3
SDRAM9
SDRAM8
GND
SDRAM7
SDRAM6
VDDQ3
SDRAM5
SDRAM4
VDDQ3
REF1
VDDQ3
REF0_2X/FS3*
GND
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
1
2
REF0_2X/FS3
X1
X2
XTAL
OSC
3
X1
4
PLL Ref Freq
X2
5
VDDQ3
PCI0/FS1*
PCI1/FS2*
PCI2
GND
PCI3
PCI4
PCI5
PCI6
VDDQ3
GND
SDRAM0
SDRAM1
VDDQ3
SDRAM2
SDRAM3
GND
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
SDRAM0:13
÷
13
VDDQ2
CPU0:2
PLL 1
3
÷
VDDQ3
PCI0/FS1
PCI1/FS2
PCI2
SDATA
48MHz_2X/FS0*
SIO/CPU3.3#_2.5*
SMBus
{
SCLK
PCI3
PCI4
PCI5
PCI6
2
SDATA
SCLK
I C
Note:
Logic
1. Internal 100-kΩ pull-down resistors present on inputs marked with *.
Design should not rely solely on internal pull-down resistors to set
I/O pins LOW.
VDDQ3
48MHz_2X/FS0
PLL2
x1/÷2
SIO/CPU3.3#_2.5
Cypress Semiconductor Corporation
•
3901 North First Street
•
San Jose
•
CA 95134
•
408-943-2600
November 16, 2000, rev. *B