Intel 4 HT 631 80552PG0802M2M Data Sheet

Product codes

80552PG0802M2M

Electrical Specifications

Datasheet

2.7.2

FSB Frequency Select Signals (BSEL[2:0])

The BSEL[2:0] signals are used to select the frequency of the processor input clock

(BCLK[1:0]).

Table 18

defines the possible combinations of the signals and the

frequency associated with each combination. The required frequency is determined by

the processor, chipset, and clock synthesizer. All agents must operate at the same

frequency.

The Pentium 4 processor will operate at an 800 MHz FSB frequency (selected by a

200 MHz BCLK[1:0] frequency).

For more information about these signals, refer to

Section 4.2

2.7.3

Phase Lock Loop (PLL) and Filter

CCA

and V

CCIOPLL

are power sources required by the PLL clock generators for the

Pentium 4 processor silicon. Since these PLLs are analog, they require low noise power

supplies for minimum jitter. Jitter is detrimental to the system: it degrades external I/O

timings as well as internal core timings (i.e., maximum frequency). To prevent this

degradation, these supplies must be low pass filtered from V

The AC low-pass requirements, with input at V

are as follows:

• < 0.2 dB gain in pass band
• < 0.5 dB attenuation in pass band < 1 Hz
• > 34 dB attenuation from 1 MHz to 66 MHz
• > 28 dB attenuation from 66 MHz to core frequency

The filter requirements are illustrated in

Figure 3

Table 18.

BSEL[2:0] Frequency Table for BCLK[1:0]

BSEL2

BSEL1

BSEL0

FSB Frequency

RESERVED

200 MHz

RESERVED