Power supply device, transistor driving method, recording medium

Abstract

The present invention provides a power supply unit (regulator circuit) capable of preventing thermal breakdown of a driven transistor that may be caused accidentally in case the collector output of the transistor is grounded. A power supply unit (10) for supplying a driving current to a base of a transistor (20) to thereby drive the same has a lower threshold comparator (14) which compares an actual collector output Vin of the transistor (20) with a lower threshold of 0.5 Vref, and sends a stop signal to a current controller (18) if the collector output Vin is less than the lower threshold of 0.5 Vref. Thus, when the collector output of the transistor (20) is grounded directly without via a load circuit (40), the collector output Vin is rendered under the lower threshold of 0.5 Vref, so that the current controller (18) receives the stop signal from the lower threshold comparator (14) and then stops the supply of the driving current to the transistor (20). Consequently, it becomes possible to prevent thermal breakdown of the transistor (20) that may otherwise be caused by any excessive supply of the driving current.

Dependencies are inferred from the claim text.