An operation method for an electronic device comprising at least one power input , which can be connected to either a switch- mode DC adapter or a DC power source, and at least one main board , which is powered from said power input characterized in that said method comprises the steps of; - powering said electronic device ; - filtering input voltage fed through said power input by at least one filtering means ; - analyzing voltage and frequency characteristic of the filtered voltage in at least one detection means ; - checking whether analysed voltage contains any high frequency component whose frequency is higher than a threshold frequency ; - after the checking high frequency components step , if at least one high frequency component is detected following steps are performed: i. checking whether detected component exist for a predetermined time or not; ii. if detected component exists for a predetermined time, identifying the power source as a switch-mode DC adapter and adjusting electronic device settings in accordance with requirements of a switch- mode DC adapter ; iii. if detected component does not exist for said predetermined time, identifying the power source as a DC source and adjusting electronic device settings in accordance with requirements of a DC source ; wherein the step of adjusting electronic device settings in accordance with requirements of a DC source further comprises the step of performing a protection method against unwanted voltage peaks, inrush currents and/or noises of the power input, and wherein in the adjusting electronic device settings in accordance with requirements of a switch-mode DC adapter step, the electronic device is started without a protection method. - powering said electronic device ; - filtering input voltage fed through said power input by at least one filtering means ; - analyzing voltage and frequency characteristic of the filtered voltage in at least one detection means ; - checking whether analysed voltage contains any high frequency component whose frequency is higher than a threshold frequency ; - after the checking high frequency components step , if at least one high frequency component is detected following steps are performed: i. checking whether detected component exist for a predetermined time or not; ii. if detected component exists for a predetermined time, identifying the power source as a switch-mode DC adapter and adjusting electronic device settings in accordance with requirements of a switch- mode DC adapter ; iii. if detected component does not exist for said predetermined time, identifying the power source as a DC source and adjusting electronic device settings in accordance with requirements of a DC source ; i. checking whether detected component exist for a predetermined time or not; ii. if detected component exists for a predetermined time, identifying the power source as a switch-mode DC adapter and adjusting electronic device settings in accordance with requirements of a switch- mode DC adapter ; iii. if detected component does not exist for said predetermined time, identifying the power source as a DC source and adjusting electronic device settings in accordance with requirements of a DC source ; <EOS>