| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a vehicular electronic control unit capable of diagnosing an action of step-up means at an arbitrary timing while retaining an output voltage with which a normal action is not hindered.SOLUTION: In a step-up and step-down circuit including semiconductor switches SW1 to SW4, a reactor L, resistors R1 and R2, a comparator 11, and a control circuit 12, a step-up action activation circuit 20 is inserted to an input voltage introduction part (reverse input terminal) of the comparator 13, into which an input supply voltage and output voltage are introduced, included in the control circuit 12. Even when an input voltage VB is not lower than the output voltage, a transistor 21 of the step-up action activation circuit 20 is turned on in order to lower the input voltage to be introduced into the reverse input terminal of the comparator 13 for the purpose of forcible switching into a step-up action mode. The on or off states or switching states of the semiconductor switches SW1 to SW4 are monitored in order to diagnose whether a step-up action is normal.</p> |
