Abstract: Provided is a communication state display method, the method being used to check a communication state of a communication device that transmits/receives signals to/from a different apparatus by serial communication, the method including: stretching a pulse width of a signal transmitted/received between the communication device and the different apparatus by serial communication; and causing current to flow through an indicator in response to the signal having the stretched pulse width to light the indicator during the current flow.

Abstract: Provided is a communication state display method, the method being used to check a communication state of a communication device that transmits/receives signals to/from a different apparatus by serial communication, the method including: stretching a pulse width of a signal transmitted/received between the communication device and the different apparatus by serial communication; and causing current to flow through an indicator in response to the signal having the stretched pulse width to light the indicator during the current flow.

Abstract: A DC-DC converter includes: a transformer including primary and secondary windings; a switching element that drives the primary winding; a comparator that compares a voltage induced in the secondary winding with a predetermined voltage to detect that the voltage is outside a predetermined voltage range; and a controller. The controller stops switching operation of the switching element when the voltage is outside the predetermined voltage range. Preferably, the DC-DC converter is of a flyback system.

Abstract: An apparatus measures a voltage of a cell while scanning a group of cells in a cell stack, in which a plurality of cells is electrically connected in series. The apparatus has a first switching device and a voltage detecting device. The first switching device is connected in series with a signal line carrying a voltage of a cell. The voltage detecting device detects the voltage of the cell, which is electrically connected with signal lines carrying voltages of cells belonging to a group. When the first switching device is electrically connected with a connecting point between two successive groups of cells, the first switching device is shared by the two groups.

Abstract: A DC-DC converter includes: a transformer including primary and secondary windings; a switching element that drives the primary winding; a comparator that compares a voltage induced in the secondary winding with a predetermined voltage to detect that the voltage is outside a predetermined voltage range; and a controller. The controller stops switching operation of the switching element when the voltage is outside the predetermined voltage range. Preferably, the DC-DC converter is of a flyback system.

Abstract: An apparatus measures a voltage of a cell while scanning a group of cells in a cell stack, in which a plurality of cells is electrically connected in series. The apparatus has a first switching device and a voltage detecting device. The first switching device is connected in series with a signal line carrying a voltage of a cell. The voltage detecting device detects the voltage of the cell, which is electrically connected with signal lines carrying voltages of cells belonging to a group. When the first switching device is electrically connected with a connecting point between two successive groups of cells, the first switching device is shared by the two groups.