cy28325-3 Cypress Semiconductor Corporation., cy28325-3 Datasheet - Page 12

• Manufacturer Part Number: cy28325-3
• Description: Ftg For Via Pentium 4 Chipsets
• Manufacturer: Cypress Semiconductor Corporation.

Document #: 38-07590 Rev. *.*
Data Byte 15
Data Byte 16
Data Byte 17
Programmable Output Frequency, Watchdog Timer and
Recovery Output Frequency Functional Description
The Programmable Output Frequency feature allows users to
generate any CPU output frequency from the range of 50 MHz
to 248 MHz. Cypress offers the most dynamic and the simplest
programming interface for system developers to utilize this
feature in their platforms.
Table 5. Register Summary .
Pro_Freq_EN
Bit
Bit
Bit
2
1
0
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
Name
Pin#
Pin#
Pin#
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
Reserved
Vendor Test Mode
Vendor Test Mode
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Programmable output frequencies enabled
0 = Disabled (default).
1 = Enabled.
When it is disabled, the operating output frequency will be determined by either the latched value of
FS[4:0] inputs or the programmed value of SEL[4:0]. If FS_Override bit is clear, latched FS[4:0] inputs
will be used. If FS_Override bit is set, programmed value of SEL[4:0] will be used. When it is enabled,
the CPU output frequency will be determined by the programmed value of CPUFSEL_N, CPUFSEL_M
and the PLL Gear Constant. The program value of FS_Override, SEL[4:0] or the latched value of FS[4:0]
will determine the PLL Gear Constant and the frequency ratio between CPU and other frequency
outputs.
Name
Name
Name
Reserved
Reserved. Set = 1
Reserved. Set = 1
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
The Watchdog Timer and Recovery Output Frequency
features allow users to implement a recovery mechanism
when the system hangs or getting unstable. System BIOS or
other control software can enable the Watchdog timer before
they attempt to make a frequency change. If the system hangs
and a Watchdog timer time-out occurs, a system reset will be
generated and a recovery frequency will be activated. All the
related registers are summarized in the following table.
Description
Pin Description
Pin Description
Pin Description
CY28325-3
Page 12 of 19
Power-on
Power-on
Power-on
Default
Default
Default
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
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