When people design electrical circuit modules or finalize new products, they rarely seriously consider the choice of supporting power supply, and do not re-evaluate this problem until they find that the problem lies in the power supply part. To help people, this article describes the definition of the parameters of a DC power supply and the potential impact of the unit under test (UUT) or other circuit system. First, the basic basis for choosing a power supply voltage and current range, these are the two easiest indicators to determine, as long as it is calculated according to the power consumption of the circuit. However, if only a single DC voltage is used to power the UUT, it should be considered to test the high and low supply voltage extremes of the UUT. Most stationary power supplies allow the output voltage to vary ± 10%, but if this is not sufficient for the circuit, a power supply with adjustable output or a larger range of variations is optional. If this power supply is used to supply a combined unit, 75 to 90 percent of the maximum current required by the device is provided by a single power supply, and two or more power supplies can be connected to the insufficient part. The power supply supplying the semi-stationary test bench must have a capacity of at least 125% of the current required for the test bench. 1. Working mode Almost all DC power supplies work in constant voltage source mode, which means that the output voltage can remain unchanged in the entire current change range. There are also a number of power supplies that can also work in value source mode within a certain range. The range of power output is not limited by the voltage or current output capability of the power supply itself, but also related to the working state of the power supply. A few power supplies also serve as electronic device loads, in which case they can be used to test other constant voltage or constant current sources. 2. Response time When the power supply can be remotely controlled or the power supply is part of the test system, then the delay time from the issuance of the control command to the stabilization of the power output to the desired value is a very important factor (e.g., turning on or changing the voltage). Response times range from a few milliseconds to tens of milliseconds. A small amount of power supply can have a fast conversion rate of more than IV/us. These power supplies can be used to create high-power arbitrary waveform generators. 3. Resolution: The minimum adjustable increment of output voltage or current limited by technical parameters. Some power supplies have the same resolution across the entire output range, while some have different resolutions over different output ranges. 2. Accuracy, Expansion and Security of Power Supply 1. Remote Sensing Characteristics In order to accurately control the voltage or current value on the load, any changes in the circuit can be fed back to the regulator circuit through an independent sensing channel, so that any change in voltage drop between the UUT and the power supply can be corrected. 2