A constant voltage power supply can provide a constant output voltage within the allowable load range. Since the LED is mainly affected by the current, the system needs to limit the current when using it. The DC output voltage of the constant voltage power supply generally has the following four fixed values: 12V, 24V, 36V, 48V.

The essence of a constant power power supply is a constant current power supply. By adjusting its output current, the output voltage will automatically adjust with the current to keep the output power constant.

An isolated power supply means that there is a transformer isolation between the input and output ends of the power supply, and there is no direct electrical connection, so the two ends are in a state of high insulation resistance, which can avoid the risk of electric shock. This type of power supply has high safety, strong anti-interference ability, wide input voltage range, and easy realization of multiple outputs.
A non-isolated power supply means that there is a direct electrical connection between the load terminal and the input terminal, so that current can flow directly from the input to the load. The advantages of this type of power supply are high conversion efficiency, small size, low cost, and easy design.

Class I and Class II are the safety levels for equipment against electric shock, mainly considering the insulation system of the product:
Class I equipment: This type of equipment refers to protection against electric shock through the use of basic insulation, and also provides protective grounding impedance. When the basic insulation fails, this grounding impedance will withstand a dangerous voltage to ground. That is to say, the “Class I” off type power supply will provide a pair of terminals for ground connection.
Class II equipment: This type of equipment not only relies on basic insulation to prevent electric shock protection, but also requires additional safety measures such as double insulation or reinforced insulation, and does not rely on grounding protection. That is to say, the switch mode power supply of “Class II” does not provide a pair of ground connected terminals.

“Class 2” comes from UL 1310 (Class 2 power units), which mainly means that the output of the product is safe, and the product meets the requirements of the relevant standards of UL1310 to mark Class 2; its single output must meet the following basic electrical properties:
1) The output DC voltage is less than 60V (Canada 42.4V) in dry and humid environments, and the output DC voltage is less than 30V in watery environments; 2) The total power is less than 100W; 3) The rated output nominal current is less than 5A (the maximum is less than 8A); 4) meet the relevant abnormal test requirements of UL1310.
“Class II” comes from the IEC standard or equivalent standard, mainly refers to the product’s anti-shock insulation structure or insulation type, generally for the whole machine, means that the product’s anti-shock protection not only relies on basic insulation, but also includes additional safety measures , such as double insulation or reinforced insulation, but without grounding or protective measures that depend on installation conditions, have their own symbols, built-in products are “double circles”, and independent products are “back”. ? ?
“Class 2” is related to the UL standard in North America, referring to the risk of electric shock or fire at the output; while “Class II” is related to the IEC standard, referring to the protection against electric shock at the input. Note: Both are read as “class two”.