Abstract: A night vision device with a switching power supply and a method of powering a night vision device with switching circuits are provided. The switching power supply converts a battery voltage to high DC voltages for powering photocathode, screen, and MCP of the night vision device. The switching power supply generates and adjusts a photocathode voltage instruction signal having a duty cycle based on the difference between a reference photocathode voltage and the output voltage of the photocathode voltage circuit. The switching power supply generates and adjusts a screen voltage instruction signal having a duty cycle based on the difference between a reference screen voltage and the output voltage of the screen voltage circuit. The switching power supply performs the automatic brightness control and auto-gating without directly sensing the output load current.