A power supply unit, comprising: an input configured to receive a direct current input voltage from a voltage source; a filter coupled to the input and configured to reduce electromagnetic interference in the input voltage; a boost stage circuit coupled with the filter and configured to regulate step up of an output of the filter to a minimum threshold voltage based on a boost regulator signal; a digital primary controller (116, 200) coupled with the boost stage circuit and configured to: control the boost regulator signal when not in a bootloader mode; assert a bootloader signal during the bootloader mode; and stop control of the boost regulator signal during the bootloader mode; a boost auxiliary circuit coupled with the primary controller (116, 200) and configured to: detect assertion of the bootloader signal; and assume control of the boost regulator signal during the bootloader mode in response to detecting the bootloader signal; a buck stage circuit coupled with the boost stage circuit and configured to regulate step down of an output voltage of the boost stage circuit to a predetermined DC output voltage based on a buck regulator signal; a secondary controller coupled with the buck stage circuit and configured to control the buck regulator signal; a bias module coupled with the boost stage circuit and configured to generate a nominal DC output voltage based on an output voltage of the boost stage circuit, a main output configured to supply the predetermined DC output voltage to a load; and a standby output configured to supply the nominal DC output voltage to the load; wherein the bootloader mode is a mode in which application code in the primary controller (116, 200) is updated. an input configured to receive a direct current input voltage from a voltage source; a filter coupled to the input and configured to reduce electromagnetic interference in the input voltage; a boost stage circuit coupled with the filter and configured to regulate step up of an output of the filter to a minimum threshold voltage based on a boost regulator signal; a digital primary controller (116, 200) coupled with the boost stage circuit and configured to: control the boost regulator signal when not in a bootloader mode; assert a bootloader signal during the bootloader mode; and stop control of the boost regulator signal during the bootloader mode; control the boost regulator signal when not in a bootloader mode; assert a bootloader signal during the bootloader mode; and stop control of the boost regulator signal during the bootloader mode; a boost auxiliary circuit coupled with the primary controller (116, 200) and configured to: detect assertion of the bootloader signal; and assume control of the boost regulator signal during the bootloader mode in response to detecting the bootloader signal; detect assertion of the bootloader signal; and assume control of the boost regulator signal during the bootloader mode in response to detecting the bootloader signal; a buck stage circuit coupled with the boost stage circuit and configured to regulate step down of an output voltage of the boost stage circuit to a predetermined DC output voltage based on a buck regulator signal; a secondary controller coupled with the buck stage circuit and configured to control the buck regulator signal; a bias module coupled with the boost stage circuit and configured to generate a nominal DC output voltage based on an output voltage of the boost stage circuit, a main output configured to supply the predetermined DC output voltage to a load; and a standby output configured to supply the nominal DC output voltage to the load; wherein the bootloader mode is a mode in which application code in the primary controller (116, 200) is updated.