The commonly seen power adapters and mobile phone chargers are all constant voltage switching power supplies. The DC voltage output of the power adapter is fixed, and its voltage variation allows for a floating range of ± 5% of the output voltage. The output of the power adapter has overvoltage, overcurrent, short circuit, and power protection functions. Constant current power supplies are generally used in LED lights, and as the name suggests, their output is constant current power supply.

Wall mounted power adapter

When the constant voltage power supply, also known as the power adapter, is within the rated output current range, that is, within the working range The output voltage will always remain within the range of ± 5% of the rated voltage When the output current is greater than 1.3-2 times the rated current, the power adapter will stop working and resume normal operation when the load power is removed Constant voltage power supply, also known as regulated power supply, requires a fixed output voltage value that does not vary with external working conditions such as load and input voltage At the same time, there are specific requirements for the maximum output current, maximum output power, working efficiency, output voltage stability, drift, ripple factor, electromagnetic compatibility (EMC) characteristics, temperature effect, noise, impedance characteristics, etc. of the power supply.

Constant current power supply, also known as steady current power supply, is not well known to us and it is relatively difficult to understand its concept The output characteristic curve of a constant current power supply is opposite to that of a constant voltage power supply The controlled parameter is the output current, and the dependent variable is the dependent voltage When the output current remains constant within the load range and the load resistance is high, the power supply enters the compliance voltage limit protection zone, and the constant current power supply considers it an overvoltage situation It is generally believed that this area is a non working protection area, and the output voltage within this area is not clearly determined We are not as familiar with the terms used to describe constant current power supplies as those used in constant voltage power supplies For a variable constant current power supply, the output current can be adjusted, usually from around 0 to a certain maximum value (referred to as the constant current range) To maintain a constant load current, the output voltage must follow the changes in load resistance The range of terminal voltage in the constant output current region is called the "dependent voltage". Compliance with voltage usually has a clear maximum value, and the application of constant current power supplies has limitations Generally used in situations where a constant current must be maintained within a limited range of load resistance variation Typical examples include LED lamp drivers, deflection and aggregation windings in electron microscopes and gas spectrometers.