Abstract: A booster circuit is incorporated in a one-chip microcomputer. In a test mode, a burn-in test is performed by switching power supply systems so that a power supply voltage of 5V is supplied to a 3.3V-type circuit section that normally operates on a power supply voltage of 3.3V in an ordinary state and a boosted voltage of a 5V booster circuit is supplied to a 5V-type circuit section that normally operates on a power supply voltage of 5V in the ordinary state.

Abstract: A transmission device includes a transmission line composed of first and second transmission lines. A first circuit block outputs a non-inverted transmission signal to the first transmission line, and a second output circuit outputs an inverted transmission signal to the second transmission line. The second circuit block comprises an impedance element and a comparison circuit for comparing voltages. The same types of impedance elements as the impedance element are interposed in the first and second transmission lines between the first circuit block and the second circuit block.

Abstract: A semiconductor integrated circuit is composed of a first integrated circuit portion for performing external communication by using a differential voltage difference between a pair of communication lines and a second integrated circuit portion that is supplied with power, and a coupling capacitor inserted in a communication line for connecting the first integrated circuit portion and the second integrated circuit portion. Each of the first integrated circuit portion and the second integrated circuit portion has an insulating separation type structure and are formed on a same semiconductor chip. A transmission device includes a transmission line composed of first and second transmission lines. A first circuit block outputs a non-inverted transmission signal to the first transmission line, and a second output circuit outputs an inverted transmission signal to the second transmission line. The second circuit block comprises an impedance element and a comparison circuit for comparing voltages.

Abstract: A booster circuit is incorporated in a one-chip microcomputer. In a test mode, a burn-in test is performed by switching power supply systems so that a power supply voltage of 5V is supplied to a 3.3V-type circuit section that normally operates on a power supply voltage of 3.3V in an ordinary state and a boosted voltage of a 5V booster circuit is supplied to a 5V-type circuit section that normally operates on a power supply voltage of 5V in the ordinary state.

Abstract: A semiconductor device including a semiconductor substrate having a main surface. An insulating film is formed on the main surface of the semiconductor substrate. A semiconductor layer is placed on the insulating film. Side insulating regions extending from a surface of the semiconductor layer to the insulating film divide the semiconductor layer into element regions. The element regions are isolated from each other by the side insulating regions and the insulating film. The semiconductor substrate has a resistivity of 1.5 .OMEGA.cm or lower. A voltage at the semiconductor substrate is set to a given voltage.