| 摘要 |
PURPOSE:To protect a transistor connected in series with the load from the load short-circuit, by providing an FET which makes a short-circuit between a base and an emitter when a fixed voltage is applied across a collector and an emitter in a chip. CONSTITUTION:A P<+> base 42 and simultaneously a P layer 42 are provided on an N type Si substrate 41, an N<+> emitter layer 43 is provided in the P<+> base 42 resulting in a transistor 31 and covered with an oxide film 48, a window is opened, metallic electrodes 45-47 are respectively laid on each region 42-43, and the electrodes 46 and 47 are connected by an electrode 49 on the oxide film 48. When the voltage VCE between the electrode 49 and the N<-> layer of the substrate 41, i.e. the collector emitter of the transistor 31 exceeds the fixed value, an inversion layer 50 generates on the surface of the N<-> layer resulting in the formation of a P channel, a MOSFET 21 operates, the base 41 of the transistor 31 is short-circuitted to the emitter 43 via the P layer 44, and accordingly the transistor 31 is in an off-state, When self-protection is performed against the load short-circuit and applied to a series source circuit, it is effective. |
