Uninterrupted power supply

The utility model relates to an uninterrupted power supply which consists of a power supply circuit, a protection circuit, a power output circuit and a lighting circuit, wherein the protection circuit is connected with the power supply circuit; the power output circuit is connected with the protection circuit; the lighting circuit is connected with the power output circuit. The uninterrupted power supply can provide 5V, 9V, 12V direct current power supplies; under the condition of the outage of a main power supply, the power supply can supply power to the load without delay; meanwhile, for the equipment with 12V power supply, a circuit interrupts the load if the battery voltage is reduced to 10.5V to prevent deep discharge of the battery. If the power supply breaks down at night, two white light emitting diodes are used as emergency lighting. The power supply is simple in structure and low in cost, and multilevel voltage is output to meet requirements of different voltages.