Patent ID: 6967391

Claim:
An electronic control device having a power supply circuit formed on a multi-layered substrate for adjusting a power supply voltage supplied by an external power supply to a desired level, the power supply circuit including a switching component to which the power supply voltage is applied at an input terminal thereof and which is driven by a duty signal comprising: an output voltage forming circuit formed in a top layer of the multi-layered substrate for producing an output voltage formed from a voltage inputted from the switching device; a ground wiring pattern that defines a ground electrical potential of the output voltage forming circuit; a common ground wiring pattern that defines a ground electrical potential of each of electronic circuits included in the electronic control device, except for the output voltage forming circuit; and a connecting part that connects the ground wiring pattern with the common ground wiring pattern, wherein the ground wiring pattern is formed in a layer of the multi-layered substrate and connected to the output voltage forming circuit, and the common ground wiring pattern is formed in a layer of the multi-layered substrate.