REVERSE POLARITY PROTECTION FOR BIPOLAR IC'S

摘要

1405503 Integrated circuits TEXAS INSTRUMENTS Ltd 16 Nov 1972 53003/72 Heading H1K In order to avoid the risk of damage due to inadvertent reversal of the supply voltage polarity the isolation region 14 of a junctionisolated integrated circuit is connected to a supply terminal 1 through the emitter-collector path of a transistor T 1 formed in one of the isolated islands 15. In the Si circuit shown p+ isolation walls 14 define islands in an N-type epitaxial layer 12 on a P-type substrate 11. The emitter region 17 of NPN transistor T 1 is connected to the walls 14 via metallization 26, the collector region being connected to the negative supply terminal 1 via metallization 28. The base region 16 is connected to the positive supply terminal via an epitaxial resistor region 19, or via the emitter-collector path of a further transistor whose base electrode is connected via a resistor to the negative supply terminal. In a modification the emitter of T 1 is connected to the negative supply while the collector is connected to the isolation region.