Patent ID: 7098626

Claim:
A power supply apparatus including a battery for driving a load and a temperature detection circuit for detecting a temperature of the battery, wherein the battery includes n (where n is an integer equal to or greater than 2) battery cells connected in series or in parallel with one another, the temperature detection circuit includes m (where m is an integer equal to or greater than 2 and fulfilling n≧m) temperature detection units, the temperature detection units each including a temperature sensor that is thermally coupled to one or more of the battery cells and whose electrical resistance decreases as a temperature of the battery cell or battery cells to which the temperature sensor is thermally coupled increases, a serial resistor that is connected in series with the temperature sensor to form a serial circuit and that permits a voltage at a node between the serial resistor and the temperature sensor to vary as the electrical resistance of the temperature sensor varies, the serial circuit receiving a predetermined voltage such that, as the electrical resistance of the temperature sensor decreases, the voltage at the node decreases, and a first diode that is connected to the node so that a forward direction thereof coincides with a direction in which a current flows toward the node, so that there are provided m temperature sensors, m serial resistors, and m first diodes in total, and the first diodes have anodes thereof connected together.