Supplying a fixed and accurate power level to a load is easy if you know the load impedance, and the impedance doesn''t change. Simply apply a constant voltage based on the formula for power in a resistive load: P = V²/R, or V = √ PR.
A constant-current power supply is a power supply circuit that controls the output current to a constant level. Constant-current power supplies are used to power LED lighting and charge rechargeable batteries.
TLDR: That power supply lets you set both a voltage limit and a current limit. If you connect a high impedance load, then the voltage will hit the limit, and the current will be controlled by the load. (i.e., it acts like a voltage source.)
The user of a benchtop DC power supply normally starts by configuring the output voltage, and in most cases the supply operates in so-called constant voltage mode because the supply delivers the same, or a constant, voltage regardless of the attached load.
Build this power supply circuit to produce a constant current, no matter the load.
Most common constant voltage drivers (or Power Supplies) are 12VDC or 24VDC. An LED light that is rated for constant voltage usually specifies the amount of input voltage it needs to operate correctly. A constant voltage power supply receives standard line voltage (120-277VAC).
In its most basic definition, a constant current is a form of power supply that regulates the current that flows through an LED array. The current helps maintain the desired level of light output without overwhelming the LED.
Constant Voltage Mode in Power Supply. Constant Voltage (CV) is the standard operating mode when it comes to power supplies. In Constant Voltage Mode, a power supply will output a set voltage across its entire load range. Figure 1 depicts a graph of Voltage vs. Load Resistance for a power supply programmed to 48V with a current limit of 80A.
A voltage source is a device that produces constant voltage, but allows amperage and power to vary, in accordance with the laws of electricity. A current source is a device that produces constant current, allowing voltage and power to vary.
Constant power supplies exist to the extent that they are needed. Nearly all grid connected supplies adjust their output voltage and current to supply a pre-arranged power level. However the range of voltage adjustment necessary is very narrow. Such supplies are said to be grid-following.