| 摘要 |
PURPOSE:An internal circuit is protected by operating an npn transistor with a current from Vcc, part of the current flowing to a resistance side, by the breakdown of the npn transistor when a pad is made of negative electric potential. CONSTITUTION:An internal circuit 5 is protected by a current (i) to the direction of an arrow from Vcc by the rise of the VBE of an npn transistor Q1 part of the current flowing in R by the breakdown of the npn transistor Q1 when the electric potential of a pad is made negative. Or, a parasitic pnp transistor Q2 is made with a substrate (p) and the internal circuit is also protected by the thyristor operation of Q1 and Q2. When the pad is made positive electric potential, a diode is formed from the resistance R to Vcc and the internal circuit is protected by a current or the reverse direction current of the Q1. |
