Datasheet

Intel
®
Pentium
®
4 Processor in the 423-pin Package
13
2.4.1 Phase Lock Loop (PLL) Power and Filter
V
CCA
and V
CCIOPLL
are power sources required by the PLL clock generators on the Pentium 4
processor silicon. Since these PLLs are analog in nature, they require quiet 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
CC
. A typical filter topology is shown in Figure 1.
The AC low-pass requirements, with input at V
CC
and output measured across the capacitor (C
A
or
C
IO
in Figure 1), is as follows:
Table 2. Voltage Identification Definition
Processor Pins
VID4 VID3 VID2 VID1 VID0 V
CC_MAX
11111VRM output off
111101.100
111011.125
111001.150
110111.175
110101.200
110011.225
110001.250
101111.275
101101.300
101011.325
101001.350
100111.375
100101.400
100011.425
100001.450
011111.475
011101.500
011011.525
011001.550
010111.575
010101.600
010011.625
010001.650
001111.675
001101.700
001011.725
001001.750
000111.775
000101.800
000011.825
000001.850