Wake-up circuit in an electric steering system

A system for determining an absolute rotational position of a rotatable shaft of a motor in an electric power steering system of a vehicle, the system comprising:

• a wake-up circuit comprising a voltage boosting circuit and a comparator circuit, the voltage boosting circuit operable to increase a back electromotive force (EMF) voltage induced on one or more inputs by rotation of the rotatable shaft of the motor and produce at least one voltage-boosted back EMF voltage, the comparator circuit operable to compare the at least one voltage-boosted back EMF voltage to a reference voltage and output a control signal based on a result of the compare during an ignition off state of the vehicle;
• and
• a monitoring system comprising a microprocessor and first and second position sensors operable to generate signals indicative of a relative rotational position of the rotatable shaft, the microprocessor configured to activate in response to the control signal and determine a current absolute position value indicating a current absolute rotational position of the rotatable shaft based on a previously stored absolute position value and an amount of relative rotation of the rotatable shaft based on the signals from the first and second position sensors.