Abstract: A dual current-limiting circuit for a dc brushless motor includes an over-current detective circuit, an operation detective circuit, and a current-limiting circuit. The over-current detective circuit produces a voltage signal used to determine whether an over-current has been input to the motor. The operation detective circuit also produces a voltage signal used to determine whether the motor is being operated in a normal manner. The current-limiting circuit decides to turn on a first switch of a first current-limiting circuit and to subsequently turn on a second switch of a second current-limiting circuit depending upon the two voltage signals. The current-limiting circuit is capable of suppressing current passing through a coil at a low voltage level, which is inadequate to damage a driver circuit and still adequate to restart the motor if an abnormal input current is eliminated.

Abstract: The dual current-limiting circuit for dc brushless motor includes an over-current detective circuit, an operation detective circuit, and a current-limiting circuit. The over-current detective circuit produces a voltage signal being used to determine whether the motor has been input over current. The operation detective circuit also produces a voltage signal being used to determine whether the motor is operated in normal. The current-limiting circuit decides to turn on a first switch of a first current-limiting circuit and to subsequently turn on a second switch of a second current-limiting circuit depending upon the two voltage signals. The current-limiting circuit is capable of suppressing current passing through a coil at low voltage level, which is inadequate to damage a driver circuit and still adequate to restart the motor if the great abnormal input current is eliminated.