| 摘要 |
<p>PURPOSE:To shield a control circuit from a noise produced in a large current circuit and avoid the misoperation of a small signal circuit by a method wherein an active filter having a circuit structure in which a reactor is connected between the output terminal of a rectifying circuit and a switching device is mounted on an insulated metal board in such a manner that the circuit elements of the filter to which large currents are applied are isolated from its small signal circuit elements by a ground pattern around the center of the circuit board. CONSTITUTION:A circuit board is divided into a small signal circuit block and a large current circuit block by a part of a grounding pattern. The large current circuit block is composed of a rectifying circuit, a switching device, diodes, etc. The small signal circuit is composed of a control circuit COM. Outer lead terminals through which the large current circuit block is connected to an external circuit are provided on the circumferential edge parts of the circuit board which are different from the circumferential edge parts on which the outer lead terminals of the small signal circuit block are provided. Therefore, noise crosstalk from the large current circuit block to the small signal circuit block through the outer lead terminals can be avoided.</p> |
