Datasheet

Electrical Specifications
30 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 Celeron D processor will operate at an 533 MHz FSB frequency (selected by a
133 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
V
CCA
and V
CCIOPLL
are power sources required by the PLL clock generators for the
Celeron D processor silicon. Since these PLLs are analog in nature, 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
TT
.
The AC low-pass requirements, with input at V
TT
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
LL LRESERVED
L L H 133 MHz
LH HRESERVED
LH LRESERVED
HH LRESERVED
HH HRESERVED
HL HRESERVED
HL LRESERVED