| 摘要 |
PURPOSE:To raise power supply voltage without operating a thermal protective circuit even at an inter-hysteresis temperature by inserting a diode between collectors of PNP and NPN transistors thereby setting the operation starting power supply voltage of an NPN switching Tr higher than that of the NPN Tr. CONSTITUTION:When power supply voltage rises at an inter-hysteresis temperature and the collector potential of an NPN Tr2 reaches 1VBE, base potential of NPN Trs 1-3 goes to 1XVBE and thereby the Trs 1-3 are turned ON. At that time, collector potential of a PNP Tr4 is equal to the collector potential of PNP Trs 5, 6. Consequently, base potential of an NPN Tr7 is lower than the collector potential of the PNP Trs 5, 6 by a level equal to the product of VBE and the number of diodes 9 and thereby the NPN Tr7 is not turned ON. According to the constitution, power supply voltage can be raised prior to function of a thermal protective circuit even when the power supply is raised at an inter-hysteresis temperature. |
