CY24239 Datasheet, PDF (8/15 Pages) Cypress Semiconductor – Spread Spectrum Frequency Timing Generator

CY24239
Table 6. Additional Frequency Selections through Serial Data Interface Data Bytes
Input Conditions
Output Frequency
Data Byte 0, Bit 3 = 1
Bit 2
SEL_3
Bit 6
SEL_2
Bit 5
SEL_1
Bit 4
SEL_0
CPU, SDRAM
Clocks (MHz)
PCI Clocks
(MHz)
1
1
1
1
91.66
30.5
1
1
1
0
75.0
25.0
1
1
0
1
100.0
33.3
1
1
0
0
83.3
27.76
1
0
1
1
66.6
33.3
1
0
1
0
105.0
26.3
1
0
0
1
110.0
27.5
1
0
0
0
133.3
33.3
0
1
1
1
91.66
30.5
0
1
1
0
75.0
25.0
0
1
0
1
100.0
33.3
0
1
0
0
83.3
27.76
0
0
1
1
91.66
30.5
0
0
1
0
75.0
25.0
0
0
0
1
100.0
33.3
0
0
0
0
83.3
27.76
Spread Spectrum
Percentage
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
–1.2%
–1.2%
–1.2%
–1.2%
–2.4%
–2.4%
–2.4%
–2.4%
Table 7. Select Function for Data Byte 0, Bits 0
Input Conditions
Data Byte 0
Function
Bit 0
CPU_F, 1:2
Normal Operation
0
Note 2
Three-state
1
Hi-Z
Note:
2. CPU and PCI frequency selections are listed in Table 2 and Table 6.
Output Conditions
PCI_F,
PCI0:5
Note 2
Hi-Z
REF0:1,
IOAPIC0,_F
14.318 MHz
Hi-Z
48MHZ
48 MHz
Hi-Z
24MHZ
24 MHz
Hi-Z
Document #: 38-07038 Rev. **
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