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:
Jul. 03, 1990
Filed:
Sep. 07, 1989
Joseph A Plagge, Nijmegen, NL;
Johannes E Algra, Drachten, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
A self-oscillating power supply circuit comprises a series arrangement of the primary winding (N.sub.1) of a transformer (TR), the main current path of a first semiconductor switch (T.sub.1) and a current measuring resistor (R.sub.1). The first semiconductor switch is driven by a second semiconductor switch (T.sub.2) which in turn is controlled by a comparator (CP). The voltage across the current measuring resistor is applied to the non-inverting input (6) of the comparator and, a reference voltage obtained from a reference voltage source (RS) is applied to the comparator inverting input (5). By arranging a capacitor (C.sub.2) between the output of the second semiconductor switch and the inverting input (5) of the comparator, the first semiconductor switch rapidly turns-off at the end of the forward phase at an accurately determined current through the primary winding. By applying a lower reference voltage to the comparator at a higher mains voltage, an output current is obtained from the transformer secondary winding (N.sub.2) for the load (L) which is substantially independent of the mains voltage.