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:
Feb. 02, 1999
Filed:
May. 01, 1997
Stephan Lohrer, Aldingen, DE;
Jean-Paul Louvel, Villingen-Schwenningen, DE;
Peter Scharlach, Villingen-Schwenningen, DE;
Deutsche Thomson-Brandt GmbH, Villingen-Schwenningen, DE;
Abstract
The invention relates to a switched-mode power supply having a switching transistor which periodically switches through a voltage which is applied to a primary winding of a transformer, having a base current network and having a switching stage for operating the switching transistor, and having a control stage for stabilizing a secondary voltage, the switching transistor having a switched-on phase, an off phase and an oscillation phase during operation. The switching transistor (TP20) of the switched-mode power supply according to the invention is switched through step by step during switching on, via a high-resistance resistor (RP05, RP06, RP07), a primary winding (6, 7) and a capacitor (CP24) . After this, the switched-mode power supply oscillates autonomously via this winding (6, 7) and is controlled by the control stage (TP24) . The switching transistor (TP20) switches through in a defined manner at the minimum of the first oscillation of the collector voltage, by means of a passive network (DP37, DP38, RP37) in parallel with the control stage (TP34). In consequence, the switch-on losses of the switching transistor are minimal. For a standby mode, the switched-mode power supply is provided with an additional network (CP38, RP38) which switches the switching transistor on for a defined time.