The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 13, 1995
Filed:
Aug. 12, 1993
San L Lin, San Jose, CA (US);
Hwa-Jyun Chen, Shinchu, TW;
Winbond Electronics North America Corp., San Jose, CA (US);
Abstract
A sensor circuit is disclosed for use with a clock circuit providing a periodic timing signal to a clock output, wherein a timing reference for the periodic timing signal is provided by a crystal connected between a crystal input and a crystal output of the clock circuit, or alternatively provided by an external periodic logic signal coupled to the crystal input. The sensor circuit provides a sensor output in a first state, thereby indicating the presence of an external periodic logic signal timing reference, in response to at least a given number of large-signal voltage transitions on the crystal input within a certain period of time, and otherwise provides a second state on the sensor output, typically to indicate the presence of a crystal timing reference. Also disclosed is a clock circuit including a sensor circuit, and further including means for disabling a feedback resistor necessary for crystal operation when the timing reference is determined to be provided by an external periodic logic signal.