LV Intel
®
Pentium
®
III Processor 512K Dual Processor Platform
32
Design Guide
The voltage regulator should be designed in conjunction with the recommended load model
referenced in Figure 19.
5.3
LV Intel
®
Pentium
®
III Processor 512K Power Requirements
This section describes the issues related to supplying power to the processor. For detailed electrical
specifications, please refer to the Low Voltage Intel
®
Pentium
®
III
Processor 512K Datasheet.
5.3.1
Voltage Tolerance
Refer to the Low Voltage Intel
®
Pentium
®
III
Processor 512K 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. Failure to meet the specifications on the
high-end tolerance can cause damage or reduce the life of the processor.
5.3.2
Multiple Voltages
The VRM 8.5 voltage regulator, which provides the Vcc
CORE
supply to the processor, can supply
voltages from +1.05 V to +1.825 V. The VRM 8.5 voltage regulator can provide adequate power
for all speed versions of the LV Intel Pentium
III
processor 512K. Refer to the VRM 8.5 DC-DC
Converter Design Guidelines document for available voltage details.
Figure 18. Detailed Power Distribution Model
Processor
Voltage Regulator
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
PACKAGE
L
PACKAGE
R
PACKAGE
L
PACKAGE
ESL
decouple
ESR
decouple
C
decouple
C
BULK
ESL
BULK
ESR
BULK
S2
Board Model
Power Supply
ESL
INPUT
ESR
INPUT
C
INPUT
Figure 19. VRM 8.5 Board Power Distribution Model
0.50m
W
12/4m
W
3.1/4nH
4*560
m
F
0.69nH
Lcon
Rcon
Cdecoup1
Ldecoup1
Rdecoup1
0.06m
W
25.4pH
Lmb1
Rmb1
10/4m
W
1.1/4nH
4*22
m
F
Cdecoup2
Ldecoup2
Rdecoup2
0.1m
W
30.3pH
Lmb2
Rmb2
10/5m
W
1.1/5nH
5*22
m
F
Cdecoup3
Ldecoup3
Rdecoup3
1
W
R
+Vsense
1
W
R
-Vsen rtn
V
CORE
V
SS
+V
SENSE
(14)
VRM 8.5
-V
SENSE
(13)
Processor
