General scheme for self-excited synchronous rectifier synchronous rectifiers.

摘要

A self-excited synchronous rectifier circuit for a power converter, wherein said circuit comprises: a first transformer (49,70) having a primary winding (N1) and a secondary winding (Ns), wherein said secondary winding having a first terminal and a second terminal; a first synchronous rectifier (SQ1) coupled to said first terminal of the secondary winding of the first transformer and having a floating control terminal with respect to ground; a first drive circuit (SQ3, SQ4) coupled to said floating control terminal of the first synchronous rectifier and said first synchronous rectifier control; and a first control signal coupled to said first drive circuit, wherein said first drive circuit controls the first synchronous rectifier as a function of polarity reversal of voltage across said first transformer and wherein said first control signal It derived from said second terminal of the secondary winding of the first transformer; a second synchronous rectifier (SQ2) coupled to said second terminal of the secondary winding of the first transformer and having a floating control terminal with respect to ground; one second circuit (SQ5, SQ6) coupled to said floating control terminal of the second synchronous rectifier and said second synchronous rectifier control; and a second control signal coupled to said second driving circuit, wherein said second drive circuit controls the second synchronous rectifier as a function of polarity reversal of voltage across said first transformer and wherein said second control signal It derived from said first terminal of the secondary winding of the first transformer.