Electronic control unit

An electronic control unit comprising:

• a microcomputer;
• a monitoring unit monitoring the microcomputer;
• an oscillator circuit generating and outputting a clock;
• a microcomputer power circuit including:
• a switching power source having a first transistor that switchingly operates on a clock-generated signal and lowering a voltage from an external power source;
• and
• a series power source having a second transistor that lowers an output voltage of the switching power source and supplying the output voltage to the microcomputer;
• a monitor power circuit including:
• a switching power source having a third transistor that switchingly operates on a clock-generated signal and lowering a voltage from the external power source;
• and
• a series power source having a fourth transistor that lowers an output voltage of the switching power source and supplying the output voltage to the monitoring unit;
• a control circuit controlling each of the transistors;
• and
• an oscillation stop detection circuit detecting a stop of a clock output from the oscillator, wherein
• the control circuit performs, in a switching operation stopped state of the transistors, a control to switch the first transistor to OFF, to switch the second transistor to ON, to switch the third transistor to ON, and to switch the fourth transistor to ON when the stop of the clock output is detected.