Browse Definitions:
Definition

power-on reset (PoR)

Contributor(s): Stan Gibilisco

A power-on reset (PoR) is a circuit that provides a predictable, regulated voltage to a microprocessor or microcontroller with the initial application of power. The PoR system ensures that the microprocessor or microcontroller will start in the same condition every time that it is powered up.

A PoR system can be a peripheral, but in sophisticated processors or controllers the PoR is integrated on the main chip. The most basic PoR system can comprise a resistor and capacitor connected together with values tailored so that, when power is first applied, the capacitor takes a predictable and constant time to charge up. For computer use, however, additional components are often required, including a circuit called a Schmitt trigger. When the PoR circuit is designed, the charge-up time should be adjusted by trial and error so that all of the processor or controller circuits can set themselves to the correct initial values before the computer begins to function.

A well-designed PoR circuit can ensure that when power is applied to a computer, it will start up properly every time (or almost every time), and will never (or rarely) freeze up right away. This feature not only saves the user a great deal of frustration, but it offers a last resort in case of a stubborn system crash: the so-called cold boot, where the computer is completely powered-down for a minute or two, and then powered-up all over again.

 

Continue reading about power-on reset:

Maxim Integrated Products discusses PoR and related functions for processors.

Dr. Howard Johnson outlines common problems that can occur with poorly designed PoR circuits.

HyperPhysics describes how a Schmitt trigger works.

This was last updated in April 2012

Start the conversation

Send me notifications when other members comment.

By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy

Please create a username to comment.

-ADS BY GOOGLE

File Extensions and File Formats

Powered by:

SearchCompliance

SearchSecurity

  • copyright

    Copyright is a legal term describing ownership of control of the rights to the use and distribution of certain works of creative ...

  • keylogger (keystroke logger or system monitor)

    A keylogger, sometimes called a keystroke logger or system monitor, is a type of surveillance technology used to monitor and ...

  • password

    A password is an unspaced sequence of characters used to determine that a computer user requesting access to a computer system is...

SearchHealthIT

SearchDisasterRecovery

  • business continuity plan (BCP)

    A business continuity plan (BCP) is a document that consists of the critical information an organization needs to continue ...

  • call tree

    A call tree -- sometimes referred to as a phone tree -- is a telecommunications chain for notifying specific individuals of an ...

  • mass notification system (MNS)

    A mass notification system is a platform that sends one-way messages to inform employees and the public of an emergency.

SearchStorage

  • RAID (redundant array of independent disks)

    RAID (redundant array of independent disks) is a way of storing the same data in different places on multiple hard disks to ...

  • data migration

    Data migration is the process of transferring data between data storage systems, data formats or computer systems.

  • compact disc (CD)

    A compact disc is a portable storage medium that can be used for recording, storing and playing back audio, video and other data ...

SearchSolidStateStorage

  • NVMe (non-volatile memory express)

    NVMe (non-volatile memory express) is a host controller interface and storage protocol to enable a solid-state drive to use the ...

  • SSD RAID (solid-state drive RAID)

    SSD RAID (solid-state drive RAID) is a methodology commonly used to protect data by distributing redundant data blocks across ...

  • Tier 0

    Tier 0 (tier zero) is a level of data storage that is faster, and perhaps more expensive, than any other level in the storage ...

SearchCloudStorage

  • RESTful API

    A RESTful application program interface breaks down a transaction to create a series of small modules, each of which addresses an...

  • cloud storage infrastructure

    Cloud storage infrastructure is the hardware and software framework that supports the computing requirements of a private or ...

  • Zadara VPSA and ZIOS

    Zadara Storage provides block, file or object storage with varying levels of compute and capacity through its ZIOS and VPSA ...

Close