cutoff

Transistor operating region, when the collector-emitter voltage is below the threshold, it is canceled by reverse bias and no base current flows. In the cutoff state, the graph showing the relationship between the collector current and the collector-emitter voltage of the transistor is in the saturation region. Therefore, to avoid cutoff, the collector-emitter voltage is normally used at a voltage above the threshold.

In a switching power supply circuit, in a choke-input type rectifier circuit for suppressing harmonic current, when the load changes greatly, a state occurs in which the main switching element is off, and the rectified output current fluctuates greatly. At this time, due to the off state of the main switching element, a state in which the reactor current becomes discontinuous and does not flow is also called cutoff.