Processor Core Voltage Plane And Decoupling - Intel 855PM Design Manual

Platform Power Requirements
solutions for V
V and V
CCP
5.9.3), V
CCP
5.9.3.

Processor Core Voltage Plane and Decoupling

Due to the high current (up to 25 A) requirements of the processor core voltage, the V
the VRM by means of multiple power planes that provide both low resistance and low inductance paths
between the voltage regulator, decoupling capacitors, and processor V
transient tolerance specifications for the worst-case stimulus shown in Figure 57, the maximum
Equivalent Series Resistance (ESR) of the decoupling solution should be equal to or less than 3 m .
Figure 2 (see Section 3.1) shows an example of a motherboard power plane stack-up that allows for both
robust, high frequency signals routing and robust V
The processor pin-map is shown in Figure 58 for reference in the discussion below. Note the highlighted
V power delivery corridor pins concentrated on the north side of the pin-map that contains forty-
CC-CORE
nine V
CC-CORE
pairs. Since access to the 24 south side pin pairs is blocked by the legacy signals, the only option
available for providing robust core power delivery to the processor is by placing the VRM and most of
the decoupling capacitors to the north of the core power delivery corridor (found on the north side of the
forty-nine V
V corridor on the north side of the processor socket. Due to the high current demand, all the V
CC-CORE
and ground vias of the processor pin-map should have vias that are connected to both internal and
CORE
external power planes. Sharing of vias between several V
106
, while Table 21 and Table 22 list the recommended decoupling solutions for the
CC-CORE
supply rails, respectively. Also, see decoupling solutions for the V
CC_MCH
(section 5.9.4) , and V
CC_MCH
/GND pin pairs while the south side of the socket contains only 24 V
/GND pin pairs). It is advised to not feed the VR from any other side other than this
CC-CORE
(section 5.9.5) supply rails in the design guide. .
power delivery.
CC-CORE
pins or ground pins is not allowed.
CC-CORE
®
Intel 855PM Chipset Platform Design Guide
(section
CC-CORE
is fed from
CC-CORE
pins. To meet the V
CC-CORE
/GND pin
CC-CORE
R
CC-CORE
CC-