METHOD OF DETECTING START CIRCUIT FAULT

To detect a faulty start circuit, with a capacitor additionally connected for detecting a fault in a start circuit, enabled without impairing start time of non-faulty start circuits.SOLUTION: An additional capacitor C1 is connected between a transistor M1 gate and a low potential power source terminal 2. Recovery time period from an operation stop until recovery of a current source circuit CS1 is measured when a potential change causing a voltage VDD of a high potential power terminal 1 to drop to a threshold voltage of transistor M1 or lower, so as to detect a fault in a starting circuit S1 on the basis of a length of the recovery time period.SELECTED DRAWING: Figure 1 【課題】起動回路の故障検出のためのコンデンサを追加接続しながらも、故障していない起動回路の起動時間を劣化させることなく、故障した起動回路を検出する。【解決手段】トランジスタＭ１のゲートと低電位電源端子２の間にコンデンサＣ１を追加接続し、高電位電源端子１の電圧ＶＤＤにトランジスタＭ１の閾値電圧以上に低下する電位変化を与えたときに、電流源回路ＣＳ１が動作停止してから復帰するまでの復帰時間を計測して、該復帰時間の長短によって起動回路Ｓ１の故障を検出する。【選択図】図１