Brushless motor driving circuit

Claim 1

A driving circuit for a brushless motor having driving coils wound on a core opposed to a rotor magnet comprising: magnetosensitive elements for detecting the rotating position of said motor by detecting the magnetic poles of said rotor magnet; driving transistors for feeding power to said driving coils of said motor; a current feedback amplifier responsive to a current detection signal obtained by detecting a current flowing in said coils and a speed signal indicative of the rotation speed of said motor and producing at an output terminal a control signal to control the amount of the current flowing in said coils; a control circuit responsive to output signals of said magnetosensitive elements and the output of said current feedback amplifier and connected to drive said driving transistors; and first capacitor means connected between said output terminal of said current feedback amplifier and a point of constant potential, whereas the first capacitor means has a value chosen for performing the function of capacitors normally connected to said driving coils to prevent inductive transients from said driving coils from passing to said control circuit.