| 摘要 |
Power transistors used as high-side power switches are typically subjected to a variety of potentially destructive conditions, such as loss of bias current or loss of a ground connection in associated control circuitry. In order to protect the power transistor upon occurrence of such a potentially destructive condition, a control electrode disable circuit (12) is provided to ensure that the power transistor will be turned off upon the occurrence of such a condition, or when the control circuits are deliberately turned off or placed in a standby mode. Turn-off of the power transistor is ensured by shunting a disable transistor (112) across the input of the power transistor, and providing a disable circuit (114) for activating the disable transistor (112) in the event of loss of bias or loss of ground in the control circuitry. Reliable activation of the disable transistor (112) is ensured by a bootstrap capacitor circuit (140) in the disable circuit. <IMAGE> |
