The present subject matter describes a heating unit. The heating unit comprises a heating element and a controlling unit coupled to the heating element to determine a desired value of a direct current (DC) voltage based on heating element parameters. The desired value is a value of DC voltage desired for operation of the heating element. The controlling unit computes a value of a duty cycle parameter based on device input parameters and the desired value of the DC voltage. The heating unit further comprises a power factor correction (PFC) unit coupled to the controlling unit and the heating element to convert an input alternating current (AC) voltage, received by the PFC unit from an AC supply, to a direct current (DC) voltage of the desired value based on the duty cycle parameter. The PFC unit provides the DC voltage to the heating element.