Abstract: A charging circuit, and method of performing the same, having a primary switching circuit that controls the transfer of energy between windings in a transformer based upon a reconstruction of a secondary winding current, in a primary winding side of the transformer, without directly sampling the secondary winding current, such that the secondary winding is isolated from the primary winding. The reconstruction of secondary winding current is performed by sampling a voltage across the primary winding reflected from the secondary winding, and integrating the sampled voltage using a current source driven according to the sampled voltage and a capacitor. The primary switching circuit operates to turn on an energizing of the primary winding when the integrated sampled voltage indicates that the flux density of the transformer, after a transfer of energy between primary and secondary windings, lowers to a predetermined level.

Abstract: A charging circuit, and method of performing the same, having a primary switching circuit that controls the transfer of energy between windings in a transformer based upon a reconstruction of a secondary winding current, in a primary winding side of the transformer, without directly sampling the secondary winding current, such that the secondary winding is isolated from the primary winding. The reconstruction of secondary winding current is performed by sampling a voltage across the primary winding reflected from the secondary winding, and integrating the sampled voltage using a current source driven according to the sampled voltage and a capacitor. The primary switching circuit operates to turn on an energizing of the primary winding when the integrated sampled voltage indicates that the flux density of the transformer, after a transfer of energy between primary and secondary windings, lowers to a predetermined level.