Auxiliary recharge

Abstract

A charging circuit supplies charge to a charge store to provide power to a controller of a power converter. The power converter includes an inductive component having a winding coupled to receive power from an input to the power converter. A switching circuit includes a field effect transistor (FET) and a switching element. The FET is coupled in series between the winding and the switching element. A controller is coupled to control the switching of the switching element, and a charge store is coupled to provide power to the controller. The charging circuit includes a current diversion circuit coupled to conduct a winding current from the FET to the charge store. The switching element is arranged to allow the winding current to flow through the current diversion circuit to the charge store.

What is claimed is: 
     
         1 . A charging circuit for supplying charge to a charge store for providing power to a controller of a power converter, the power converter comprising:
 an inductive component having a winding coupled to receive power from an input to the power converter;   a switching circuit comprising a field effect transistor (FET) and a switching element, the FET coupled in series between the winding and the switching element;   a controller coupled to control the switching of the switching element; and   a charge store coupled to provide power to the controller;   the charging circuit comprising:   a current diversion circuit coupled to conduct a winding current from the FET to the charge store; and   the switching element arranged to allow the winding current to flow through the current diversion circuit to the charge store.   
     
     
         2 . The charging circuit of  claim 1 , wherein the switching element is a decoupling element. 
     
     
         3 . The charging circuit of  claim 2 , wherein, the decoupling element is coupled to receive a winding current wherein the winding current is a current derived from the winding. 
     
     
         4 . The charging circuit of  claim 1 , wherein the controller is a switching controller. 
     
     
         5 . The charging circuit of  claim 1 , wherein the decoupling element is arranged to decouple a control line of the FET. 
     
     
         6 . The charging circuit of  claim 1 , wherein the FET conducts the winding current to the current diversion circuit. 
     
     
         7 . The charging circuit of  claim 1 , wherein the current diversion circuit comprises a diode configured to conduct the diverted winding current when forward-biased. 
     
     
         8 . A charging circuit for supplying charge to a charge store for providing power to a controller of a power converter, the power converter comprising:
 an inductive component having a winding coupled to receive power from an input to the power converter;   a switching circuit comprising a field effect transistor (FET) and a switching element, the FET coupled in series between the winding and the switching element;   a controller coupled to control the switching of the switching element; and   a charge store coupled to provide power to the controller, the charging circuit comprising:   means for conducting current from the winding through the FET; and   means for diverting the current through a conduction path to the charge store.   
     
     
         9 . The charging circuit of  claim 8 , wherein the switching element is a decoupling element. 
     
     
         10 . The charging circuit of  claim 9 , wherein the decoupling element is a transistor.