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Method for detecting secure and safe voltage levels for a microprocessor

IP.com Disclosure Number: IPCOM000008684D
Publication Date: 2002-Jul-02
Document File: 7 page(s) / 6M

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for detecting secure and safe voltage levels for a microprocessor. Benefits include improved functionality and improved reliability.

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Method for detecting secure and safe voltage levels for a microprocessor

Disclosed is a method for detecting secure and safe voltage levels for a microprocessor. Benefits include improved functionality and improved reliability.

Background

              Conventional X86 processors are required to be booted at a safe voltage for secure operation. They are also required to be able to be put in standby at a much lower voltage. Voltage levels too

high can damage the processor, resulting in failure.

              Advanced X86 processors incorporate a number of functions that are required to be secure and can only be accessed by test engineers. These functions must not be accessible after the part is sold. Doing so could compromise intellectual property. These secure features are controlled with Programmable ROM bits that require a minimum voltage to be read successfully. Many other functions that an X86 processor performs during boot do not work below a certain voltage. Therefore, an X86 processor is required to not start its boot sequence until voltage has reached a minimum safe level.

              Some advanced microprocessors incorporate a low-power feature that enables the processor to enter a standby mode where the external voltage is lowered. This voltage may be lower than that required for a safe boot of the microprocessor. Therefore, it must recognize that the CPU is being put into standby and not being booted. The voltage must be lowered without disrupting usage. However, if the standby voltage is too low, the processor can experience undetected data corruption, which can cause failures. Therefore, the processor must be able to detect this condition and return to the start-of-boot condition, enabling the low-voltage condition to be detected.

              Any silicon process with which a microprocessor has been fabricated has a maximum voltage that the gate oxide can tolerate before breakdown. Subjecting a processor to this voltage for even a small period can cause permanent damage to the microprocessor and cause usage failures. A microprocessor must be able to detect this condition and cause the external voltage to be removed.

              Conventional micro-architectures have not incorporated secure features and low-power stand-by features on the same processor. Most processors have incorporated circuitry to detect minimum safe boot levels but not with circuitry to enable lower-voltage standby mode. In addition, many processors have not incorporated circuitry to protect against high voltage operation. Circuitry typically detects very low voltage but not for preventing data corruption during operation.

 


General description

              The disclosed method is a procedure and circuit to provide for safe and secure operation of X86 microprocessors over varying voltages. The disclosed method includes a procedure within which the processor is prohibited from booting with insufficient voltage but enables lower standby operation after a successful boot. In addition, the disclosed method includes a procedure within which the...