Patent ID: 8378418

Claim:
A battery pack comprising: a semiconductor device; a control circuit connected to the semiconductor device; and a battery having a minus terminal that is connected directly to the second principle electrode of the semiconductor device, wherein the battery pack has a minus terminal that is connected to the first principle electrode of the semiconductor device, wherein the semiconductor device includes a first transistor fabricated on a substrate, the first transistor having a first principle electrode; a second transistor fabricated on the substrate, the second transistor having a second principle electrode, the first and second transistors being connected in series between the first and second principle electrodes, an on-state current of the first transistor flowing in a direction reverse to an on-state current of the second transistor; a first diode which is connected to the first transistor in parallel, so that a forward current of the first diode flows in a direction that is reverse to the direction of the on-state current of the first transistor; and a second diode which is connected to the second transistor in parallel, so that a forward current of the second diode flows in a direction that is reverse to the direction of the on-state current of the second transistor, wherein the first transistor has a breakdown voltage that is different from a breakdown voltage of the second transistor, and wherein the first and second transistors are MOS transistors but neither of them have double sidewall gate insulation films.