Patent ID: 7239168

Claim:
A method for measuring current by a single sensor for a two-phase motor, drive current to the two phases switched by a first set of upper and lower switches to drive a first phase of a motor and a second set of upper and lower switches to drive a second phase of a motor, with the switches being controlled by a plurality of pulse width modulation signals, the method comprising the steps of: reading a duty cycle of each drive current to a respective winding; providing two ramp signals for a pulse width modulation controller for controlling the switches, the ramp signals being approximately one half cycle out of phase, the first ramp signal for controlling the first set of switches and the second ramp signal for controlling the second set of switches; configuring the pulse width modulation signals to provide at least one timing window wherein at least one of the windings of the motor is being driven while the other winding is not being driven, and to provide a relative timing offset of approximately one-half cycle between the pulse width modulation signals driving a first winding and a second winding of the motor; gating the first and second set of switches using the respective ramp signals from the configuring step; and sampling the current of the at least one of the windings during the at least one timing window.