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Method for Gray coding a processor voltage identification signal

IP.com Disclosure Number: IPCOM000019845D
Publication Date: 2003-Oct-01
Document File: 3 page(s) / 79K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for Gray coding a processor voltage identification signal. Benefits include improved functionality, improved reliability, improved power performance, and improved performance.

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Method for Gray coding a processor voltage identification signal

Disclosed is a method for Gray coding a processor voltage identification signal. Benefits include improved functionality, improved reliability, improved power performance, and improved performance.

Background

         Conventional voltage identification (VID) tables use a standard binary sequence (or some other binary sequence) that results in more than one VID bit changing when transitioning between adjacent values in the VID table.

         A processor provides a binary VID signal to a voltage regulator (VR) that provides power to the processor. This VID signal dictates to the VR the voltage that the VR must provide to the processor for successful operation. Higher voltages support higher clock rates (and improved performance) but also cause increased heat generation. The voltage regulator module (VRM) standards specification includes a VID table that maps the various binary VID signals to the associated core voltages. Typically, the voltages in the VID table are separated by a regular interval, such as 12.5 mV.

         Many technologies, including the C1E and C2E states and thermal monitor 2 (TM2), involve having the processor change the VID signal to the VR to a value representing a lower core voltage. Typically, the processor checks entries in the VID table from the starting VID signal to the destination VID signal, stopping briefly at each intervening VID signal in the VID table. This procedure is intended to keep the VR from shutting down immediately after getting a new VID signal. If the voltage change is too great, the VR detects that difference as a failure of the VR to successfully regulate the voltage.

         Because the VID signals are multiple parallel signals that must travel a finite distance from the processor to the VR, some VID signal transitions reach the VR faster than others. The VR may interpret this brief condition as too large a VID table change and, in response, shut down.

         Binary Gray codes have the convenient characteristic of changing only a single bit when transitioning between adjacent values.

General description

         The disclosed method is Gray coding a processor voltage identification signal.

Advantages

         Some implementations of the disclosed structure and method provide one or more of the following advantages:

•         Improved functionality due to providing Gray coding of the VID table while the system is running

•         Improved reliability due to eliminating VID signal race conditions

•         Improved power performance due to improving the power delivery portion of the motherboard because the VID traces are not required to be equalized in length
•         Improved power performance due to minimizing thermal issues

•         Improved power performance due to prolonging battery life

•         Improved power performance due to minimizing f...