Sometimes it's really hard to tell the difference between constant voltage power supplies and constant current power supplies. So how do we distinguish between them? The premise is that we have a certain understanding of both constant voltage power supplies and constant current power supplies.
Constant current power supply: Also known as a constant current power supply, as the name suggests, it means that the output current is constant. The output characteristic curve of a constant current power supply is the opposite of that of a constant voltage power supply. The controlled parameter is the output current, and therefore the variable is the dependent voltage. For a 12V, 2A power supply, the normal "operating range" is from 0 ohms (short circuit) to 6 ohms. Within this load range, the output current remains constant. When the load resistance is greater than 6 ohms, it will enter the dependent voltage limiting protection zone. The constant current power supply considers this an overvoltage condition. This area is generally considered to be the non-operating protection area, and the output voltage in this area has no clear definition.
Constant voltage regulated power supply: Constant voltage means the output voltage remains constant. For a 12V, 2A power supply, the normal operating range of a constant voltage power supply is from infinite load resistance (open circuit) to 6 ohms. Within this range, with a load current of 2A or less, the voltage remains constant at 12V. When the load resistance is less than 6 ohms, the switching power supply enters the current-limiting operating region. In constant voltage power supplies, this is called an overload condition. The output voltage will decrease to zero as the load resistance changes to zero (short circuit). The output current is limited to a safe maximum value; however, this region is generally considered the non-operating region, and the current-limiting characteristics are not specifically described.
A constant voltage regulated power supply, also called a voltage regulator, requires that the output voltage value remain constant and does not change with variations in external operating conditions such as load and input voltage. It also has specific requirements for characteristics such as maximum output current, maximum output power, operating efficiency, output voltage stability (drift), ripple factor, electromagnetic compatibility, temperature effect, noise, and impedance characteristics.
