| 摘要 |
PURPOSE:To prevent breakdown by the negative polar static electricity of a bipolar type semiconductor IC by mounting a protective element between a power terminal and a base for a bipolar type transistor connected to the power terminal. CONSTITUTION:A protective element 50 is connected between a power terminal 40 and a common base for lateral type P-N-P transistors Trs. The element 50 is constituted of an N-P-N transistor, a collector electrode 53 is attached to an N<+> region 52, a P region 54 consists of sections 55a, 55b, 55c, and a base electrode 56 is annexed at the end of the section 55b. An emitter electrode 58 is added to an N<+> region 57 having a large area at the end of the section 55c. Consequently, the section 55a is equivalent to a diode because of a common connection between the electrodes 56, 58, a base and an emitter. Reverse withstanding voltage between a base and a collector for the element 50 is selected at a value smaller than reverse withstanding voltage among emitters and bases for the P-N-P Trs and larger than voltage between terminals 40, 41. Even when the static electricity of negative polar large voltage is mixed to a power line, reverse currents flow through the base from the collector for the element 50, and a section between the collector and the base for the element 50 is not broken thermally by the base resistance of the element 50 at that time, thus protecting the Trs. |
