Cold spare circuit for CMOS output circuit

摘要

A first cold spare circuit has first and second transistors, and a second cold spare circuit has third and fourth transistors. The first transistor has a gate controlled by a function of a first chip. A second transistor has its source and drain connected in series with the source and drain of the first transistor between the output and a first potential terminal. A third transistor has a gate controlled by a function of a second chip. A fourth transistor has its source and drain connected in series with the source and drain of the third transistor between the output and a second potential terminal. A first control circuit controls the gate of the second transistor and a second control circuit controls the gate of the fourth transistor so as to turn on one of the second and fourth transistors at a time.