A power supply control circuit of a three-phase brushless DC (BLDC) motor is provided. The control circuit includes means for calculating the DC current consumption IS based on a phase current signal Ishunt of the BLDC motor, the means including a shunt resistor Rshunt, an amplifier and a low pass filter. The amplifier is configured to amplify a measured voltage Vshunt that corresponds to the current Ishunt across the resistor Rshunt and perform an offset correction. The low pass filter is configured to provide a filtered voltage VO of the voltage Vshunt. The DC current IS is calculated based on the voltage VO.