Spindle speed detection through current sensing during boost braking

摘要

A circuit includes a comparator having input terminals configured to be coupled across a drive transistor adapted to drive a phase of a motor. The comparator senses a drive current of the motor phase, said sensed drive current represented by a periodic signal whose period is indicative of motor speed. A motor speed calculation circuit receives the periodic signal and processes the periodic signal to determine a speed of the motor.

主权项

1. A circuit, comprising:
a first comparator having a first input terminal configured to receive a first voltage at a first conduction terminal of a drive transistor adapted to drive a phase of a motor and having a second input terminal configured to receive a second voltage at a second conduction terminal of the drive transistor, the first comparator configured to compare the first and second voltages and output a first periodic signal having a first period indicative of motor speed; and a motor speed calculation circuit having an input coupled to receive the first periodic signal, said motor speed calculation circuit configured to process the first periodic signal and determine the first period.