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:
Aug. 25, 1981
Filed:
Apr. 16, 1979
Robert B Jarrett, Tempe, AZ (US);
Wilson D Pace, Tempe, AZ (US);
Motorola, Inc., Phoenix, AZ (US);
Abstract
An interface circuit is disclosed for receiving a ground-referenced A.C. signal for detecting transitions of the A.C. signal about ground potential. An input transistor is enabled when the A.C. signal voltage falls below ground potential by one base-emitter forward drop. The input transistor is disabled when the A.C. signal voltage rises above ground potential by one base-emitter forward drop. A feedback circuit and a bias circuit are coupled to the input transistor for switching the threshold levels of the input transistor. The interface circuit employs a hysteresis-type switching action for improving noise immunity while providing a symmetric output waveform. The circuit requires only a single power supply and is suitable for fabrication as a highly dense, monolithic integrated circuit. Also, the circuit provides a low input impedance to large positive and negative voltage transients.