Clock Generation - Intel 810A3 Design Manual

Chipset platform
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Clocking
6.1

Clock Generation

There is only one clock generator component required in an Intel
CK810 is a mixed voltage component. Some of the output clocks are 3.3V and some of the output
clocks are 2.5V. As a result, the CK810 device requires both 3.3V and 2.5V. These power supplies
should be as clean as possible. Noise in the power delivery system for the clock driver can cause
noise on the clock lines.
The clocking chip comes in a single 56-pin SSOP package. This provides the clock frequencies
listed in
Table
Table 6-1. Intel
810A3 Chipset Clocks
Number
3
9
8
2
2
2
1
Features (56 Pin SSOP Package)
3 copies of processor Clock 66 MHz/100 MHz (2.5V) [CPU, GCH, ITP]
9 copies of 100 MHz (all the time) SDRAM Clock (3.3V) [SDRAM[0:7], DClk]
8 copies of PCI Clock (33 MHz ) (3.3V)
2 copies of APIC Clock @16.67 MHz or 33 MHz, synchronous to CPU Clock (2.5V)
2 copy of 48 MHz Clock (3.3V) [Non SSC]
2 copies of 3V66 MHz Clock (3.3V)
1 copy of REF Clock @14.31818 MHz (3.3V) also used as input strap to determine APIC
frequency
66 MHz or 100 MHz CPU operation (selectable at power up only)
Ref. 14.31818 MHz Xtal Oscillator Input
Power Down Pin
Spread Spectrum Support
2
I
C Support for turning off unused clocks
®
Intel
810A3 Chipset Design Guide
6-1.
Clock
Frequency
CPU Clocks
66/100 MHz
SDRAM Clocks
100 MHz
PCI Clocks
APIC Clocks
16.67/33 MHz
48 MHz Clocks
3V66 MHz Clocks
REF Clock
14.31818 MHz
33 MHz
48 MHz
66 MHz
Clocking
810A3 chipset system. The
6
6-1

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