Insulation synchronous rectification type DC / DC converter

摘要

To provide an insulation synchronous rectification type DC/DC converter capable of detecting source open abnormalities of source terminals in a synchronous rectification controller.SOLUTION: A synchronous rectification controller 300A comprises: drain terminals D21 and D22 connected with drains of synchronous rectification transistors M21 and M22; source terminals S21 and S22 connected with sources of the synchronous rectification transistors; comparators 305 and 306 that compare drain voltages of the drain terminals with a predetermined threshold voltage that uses a potential of the source terminals as a reference; a flip-flop 304 that receives off signals outputted from the comparators; drivers Dr21 and Dr22 that output gate signals to the synchronous rectification transistors on the basis of an output signal of the flip-flop; and a first abnormality detection circuit that includes an abnormality detection comparator 307A for comparing a voltage of the source terminals with a detection threshold voltage, and outputs a first abnormality detection signal on the basis of its output.SELECTED DRAWING: Figure 1