Voltage Regulator Module (VRM) and Enterprise Voltage Regulator-Down (EVRD) 10.0 Design Guidelines

VRM and EVRD 10.0 Design Guidelines
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1 Applications
This document defines DC-to-DC converters designed to help meet the power requirements of the
Intel® Xeon™ processor with 800 MHz system bus and Low Voltage Intel® Xeon™ processor
with 800 MHz system bus. The intent of this document is to define the electrical, thermal, and
mechanical specifications for VRM 10.0.
VRM – The Voltage Regulator Module (VRM) designation in this document refers to a voltage
regulator that is plugged into a baseboard where the baseboard is designed to support more than
one processor. VRM output requirements in this document are intended to match the needs of a
set of microprocessors.
EVRD – The Enterprise Voltage Regulator-Down (EVRD) designation in this document refers to
a voltage regulator that is embedded in a baseboard where the baseboard is designed to support
more than one processor. EVRD output requirements in this document are intended to match the
needs of a set of microprocessors. Each implementation of a specific baseboard must meet the
specifications of all processors supported by the baseboard.
The specifications in the respective processors’ datasheet always take precedence over the data
provided in this document.
VRM/EVRD 10.0 incorporates functional changes from prior VRD and VRM guidelines:
• Vcc and Vtt supplies are separate (the Vtt specifications are included in the respective
processors’ datasheet).
• Addition of a continuous load current (ICC (TDC)) to enable cost effective VRM/EVRD
designs (Section 2.1).
• Addition of dynamic VID to change the output voltage during normal operation in response
to an input from the processor (Section 2.7).
• Simplified definition of power-good as a power-up indication (Section 6.1).
• Extended use of the VRM/EVRD disable function to turn off the output in response to an
input from the processor (Section 3.1).
• Specifications added to monitor and react to excessive temperature in the voltage regulator
(VR) (Section 6.2)
1.1 Terminology
A ‘#’ symbol after a signal name refers to an active low signal, indicating a signal is in the
asserted state when driven to a low level. For example, when VRM_pres# is low, it indicates that
a VRM is present in the connector.
Table 5 specifies the voltage level corresponding to the state of VID[5:0]. A ‘1’ in this table
refers to a high voltage level and a ‘0’ refers to a low voltage level.