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:
May. 05, 1998
Filed:
Jun. 19, 1996
Peter Preller, Munchen, DE;
Siemens Aktiengesellschaft, Munich, DE;
Abstract
A switch-mode power supply has a control device with an input for a control voltage which is coupled to a secondary voltage and an output for controlling a transistor that is connected in series with a primary winding of a switch-mode power supply transformer. The control device additionally includes a device for inhibiting the switching transistor from switching on again when a control error that is formed in the control device is less than a reference value. The control signal input and the output of the control device are coupled through a coupling element having a low-pass filter characteristic. A switching-on pulse for the switching transistor is consequently superimposed on the control voltage, with a time delay. If the load to be supplied is small (standby mode), the switching of the switching transistor is inhibited until the switching-on pulse which is coupled to the control voltage has decayed. A stable switching frequency slightly above the audibility limit can be set for the standby mode. The power loss is accordingly low.