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:
Jan. 01, 1991
Filed:
Dec. 04, 1989
Lalit O Patel, Mesa, AZ (US);
AG Communication Systems Corporation, Phoenix, AZ (US);
Abstract
A thermal protection circuit for an integrated circuit subscriber line interface is disclosed. The thermal protection circuit monitors the temperature of the integrated circuit and develops an output voltage signal that shuts-down the integrated circuit when a specific temperature is exceeded. The thermal protection circuit includes first and second current networks arranged to each develop first and a second currents respectively, of substantially the same value. The second current develops a reference voltage which is applied to an output transistor. When the base-emitter junction voltage of the output transistor is less than or equal to the reference voltage, the transistor begins to operate. This increases the current flowing through the first current network which is replicated in the second current network. The increased current flowing in the second current network increases the reference voltage, thereby, fully operating the output transistor and developing the output voltage signal.