Abstract: A period adjustment circuit of disconnection and restart IC comprises a second capacitor, which is connected to a resistor and a transistor connected in parallel. One end of the resistor is connected between the disconnection and restart IC and the first capacitor. When lockup of a fan motor occurs, in addition that an IC current source charges the first capacitor, the second capacitor also charges the first capacitor via the resistor until the voltage of the first capacitor reaches a disconnection voltage. The IC then enters into the disconnection state, and the voltages of the two capacitors are equal so that the second capacitor no longer charges the first capacitor. Next, the IC current source simultaneously charges the first and second capacitors until the voltage of the first capacitor reaches a system reset voltage. The first capacitor is then discharged to a restart voltage by the IC.