SWITCHING CONVERTER, CONTROL CIRCUIT THEREFOR, CONTROL METHOD, ILLUMINATION DEVICE EMPLOYING THE SAME, AND ELECTRONIC APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide a switching converter capable of detecting a failure or abnormality, and a control circuit therefor.SOLUTION: A current limit comparator 202 asserts a reset pulse S11 if a current detection signal Vcorresponding to a voltage drop of a detection resistor Rexceeds a first threshold V. A zero current detection circuit 204 generates a set pulse S13 that instructs turn-on of a switching transistor M1. A logic circuit 206 generates an output pulse S14 in accordance with the reset pulse S11 and the set pulse S13. A second comparator 212 asserts a compare signal S15 if the current detection signal Vexceeds a second threshold V. An abnormality detection circuit 214 defines the lapse of a first time from the turn-on of the switching transistor M1 as an abnormality detection term and, if the compare signal S15 is asserted during the abnormality detection term, discriminates it as an abnormality.SELECTED DRAWING: Figure 3