DC/DC refers to a device that converts a DC power supply of a certain voltage level into a DC power supply of another voltage level. DC/DC is divided into two types according to the voltage level transformation relationship: boost power supply and buck power supply, and isolated power supply and non isolated power supply according to the input output relationship. For example, the power supply for security monitoring generally uses PoE or DC 12V DC power supply, which is reduced to 5V or 3.3V through the first level DCDC converter, and then reduced to provide power for DSP, DDR, and PHY through the second level DCDC converter.