Abstract: An electronic circuit designing method and apparatus designs an electronic circuit by CAD, by generating design constraints with respect to the electronic circuit based on at least one of general layout and wiring information related to devices and wirings included in the electronic circuit, user requirements defined by a user, and user resources defined by the user, and urging an input to the user by displaying the design constraints.

Abstract: A protection circuit is used for a battery unit which has a plurality of cell parts coupled in parallel, and first and second power supplying terminals, where each of the cell parts includes a plurality of battery cells coupled in series, and first and second terminals respectively coupled to the first and second power supplying terminals. The protection circuit includes a plurality of switching elements making an electrical connection to the first terminal of a corresponding one of the cell parts and the first power supplying terminal, and disconnecting the electrical connection in response to an active signal, and a voltage monitoring circuit outputting the active signal to the switching elements when a voltage of at least one battery cell within one cell part falls outside a predetermined range, independently with respect to each of the cell parts.