| 摘要 |
PURPOSE:To protect an internal element from surges in both positive and negative directions without damaging the function of an integrated circuit by adding a current limiting circuit against a surge, through which a protective diode is directed in the opposite direction, and limiting the currents of the internal element. CONSTITUTION:A resistor 10 is constituted between electrodes 6, 7 in an N type diffusion region 4 selectively formed in an N type epitaxial region 2 and a P type diffusion region 3, a diode 12 is constituted by a P-N junction between a P type insulating isolation region 1 and the N type epitaxial region 2, and a P-N-P transistor 11 using each region 3, 2, 1 as an emitter, a base and a collector respectively is constituted. When a positive surge is applied, the transistor 11 is operated by the voltage drop section of the resistor 10 to absorb the surge, and currents flowing through an internal element 9 are limited. When a negative surge is applied, voltage applied to the internal element 9 in the forward direction of the diode 12 is limited. |
