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Browse Prior Art Database

Oscillator Failure Detection Scheme

IP.com Disclosure Number: IPCOM000122754D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 1 page(s) / 43K

Publishing Venue

IBM

Related People

Emeigh, RD: AUTHOR [+6]

Abstract

A scheme for detecting when a crystal oscillator has failed is disclosed. When the oscillator fails, an output pin will change states indicating a failure has occurred. The output pin is monitored by a microprocessor which will bring the error to the attention of the system.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Oscillator Failure Detection Scheme

      A scheme for detecting when a crystal oscillator has failed is
disclosed.  When the oscillator fails, an output pin will change
states indicating a failure has occurred.  The output pin is
monitored by a microprocessor which will bring the error to the
attention of the system.

      A block diagram for this oscillator detection scheme is shown
in the figure.  The detection scheme is made up of four books which
are listed and discussed below.

      RECEIVER - The receiver is used to receive the external
reference oscillator and convert it to signal levels used by the
oscillator detection circuitry.

      TRANSITION DETECTOR - The transition detector looks to make
sure the oscillator is operating properly.  If the oscillator is
oscillating, both outputs from this block are low.  If the oscillator
is stuck high, one of the two outputs will go high.  If the
oscillator is stuck low, the other output will go high.

      OR GATE - The OR gate is used to OR the two outputs from
the transition detector.  Therefore, either a stuck high or stuck low
oscillator will generate an error.

      DRIVER - The driver is used to convert the signal levels of the
oscillator detection circuitry to levels compatible with other
components that are used to monitor the output of this detection
circuitry.

      Disclosed anonymously.