Intel
®
Pentium
®
III Processor with 512KB L2 Cache Dual Processor Platform Design Guide
5-3
To completely model the motherboard system, one must include the inductance and resistance which
exists in the cables, connectors, PCB planes, pins and body of components (such as resistors and
capacitors), processor socket and voltage regulator. A more detailed model showing these effects is
shown in
Figure 5-3
below.
Both VRD and VRM solutions should be designed in conjunction with the recommended load model
referenced in
Figure 5-4
.
5.3
Dual Processor Power Requirements
This section describes the issues related to supplying power to an Intel
®
Pentium
®
III Processor with
512KB L2 Cache. For detailed electrical specifications, please refer to the Intel
®
Pentium
®
III Processor
with 512KB L2 Cache Datasheet.
5.3.1
Voltage Tolerance
Refer to the Intel
®
Pentium
®
III Processor with 512KB L2 Cache Datasheet for voltage tolerance
specifications. Failure to meet these specifications on the low-end tolerance results in transistors slowing
down and not meeting timing specifications. Not meeting the specifications on the high-end tolerance
can cause damage or reduce the life of the processor.
Figure 5-3. Detailed Power Distribution Model for System with VRM
Figure 5-4. VRM 8.5 Board Power Distribution Model
Processor
Voltage Regulator Module
S1
Equivalent model
CHf
LHf
RHf
L
VR
R
VR
R
CABLE*
L
CABLE*
psu
R
CABLE*
L
CABLE*
R
BOARD
*
L
BOARD
*
R
BOARD
*
L
BOARD
*
R
SOCKET
L
SOCKET
R
SOCKET
L
SOCKET
ESL
decouple
ESR
decouple
C
decouple
C
BULK
ESL
BULK
ESR
BULK
S2
Board Model
Power Supply
ESL
INPUT
ESR
INPUT
C
INPUT
0.50m
Ω
12/4m
Ω
3.1/4nH
4*560
µ
F
0.69nH
Lcon
Rcon
Cdecoup1
Ldecoup1
Rdecoup1
0.06m
Ω
25.4pH
Lmb1
Rmb1
10/4m
Ω
1.1/4nH
4*22
µ
F
Cdecoup2
Ldecoup2
Rdecoup2
0.1m
Ω
30.3pH
Lmb2
Rmb2
10/5m
Ω
1.1/5nH
5*22
µ
F
Cdecoup3
Ldecoup3
Rdecoup3
1
Ω
R
+Vsense
1
Ω
R
-Vsen rtn
V
CORE
V
SS
+V
SENSE
(14)
VRM 8.5
-V
SENSE
(13)
Processor
