A switching mode power supply, SMPS, of an image forming apparatus, the SMPS comprising: a transformation unit to transform an alternating-current voltage input to the SMPS into at least one direct-current voltage by using a transformer; a first output voltage output unit to output the transformed DC voltage as a first output voltage of the SMPS; and a second output voltage output unit to output the transformed DC voltage as a second output voltage of the SMPS; characterised in that: the second output voltage output unit comprises: a first switching unit to prevent output of the second output voltage if a cover of the image forming apparatus is open; and a second switching unit to prevent output of the second output voltage if the image forming apparatus is in a power saving mode; wherein the second switching unit is located subsequent to the first switching unit in a current flowing direction; and wherein the second switching unit is located closer to a terminal of the SMPS to output the second output voltage in comparison to the first switching unit; and wherein the SMPS further comprises: a delay unit to delay a turn-on time of the second switching unit; and a directional element to discharge electric charges charged by the delay unit if the cover of the image forming apparatus is open. a transformation unit to transform an alternating-current voltage input to the SMPS into at least one direct-current voltage by using a transformer; a first output voltage output unit to output the transformed DC voltage as a first output voltage of the SMPS; and a second output voltage output unit to output the transformed DC voltage as a second output voltage of the SMPS; characterised in that: the second output voltage output unit comprises: a first switching unit to prevent output of the second output voltage if a cover of the image forming apparatus is open; and a second switching unit to prevent output of the second output voltage if the image forming apparatus is in a power saving mode; wherein the second switching unit is located subsequent to the first switching unit in a current flowing direction; and wherein the second switching unit is located closer to a terminal of the SMPS to output the second output voltage in comparison to the first switching unit; and wherein the SMPS further comprises: a delay unit to delay a turn-on time of the second switching unit; and a directional element to discharge electric charges charged by the delay unit if the cover of the image forming apparatus is open. the second output voltage output unit comprises: a first switching unit to prevent output of the second output voltage if a cover of the image forming apparatus is open; and a second switching unit to prevent output of the second output voltage if the image forming apparatus is in a power saving mode; a first switching unit to prevent output of the second output voltage if a cover of the image forming apparatus is open; and a second switching unit to prevent output of the second output voltage if the image forming apparatus is in a power saving mode; wherein the second switching unit is located subsequent to the first switching unit in a current flowing direction; and wherein the second switching unit is located closer to a terminal of the SMPS to output the second output voltage in comparison to the first switching unit; and wherein the SMPS further comprises: a delay unit to delay a turn-on time of the second switching unit; and a directional element to discharge electric charges charged by the delay unit if the cover of the image forming apparatus is open. a delay unit to delay a turn-on time of the second switching unit; and a directional element to discharge electric charges charged by the delay unit if the cover of the image forming apparatus is open.