A constant voltage driver provides a specified output voltage for the permissible load conditions. The use of constant voltage drivers in the design requires limiting the current in the system. Constant voltage drivers are generally available with four fixed output voltages of 12, 24, 36 and 48 Vdc.

A constant current driver provides a specified output current for the permissible load conditions. Designs using constant current drivers can be connected directly to the LEDs without additional restrictions, as the LEDs respond directly to the current.

A constant power driver is a constant current driver with an adjustable output current, simultaneously the output voltage of the driver can be automatically adjusted according to the set output current, thus ensuring that the power that can be output from the driver is constant.

Isolated design means that there is no direct electrical connection between the primary side and secondary side of the transformer and that two sections are insulated from each other in a high resistance state. The advantages are high safety, high interference immunity, easy implementation of multiple outputs and a wide input voltage range.

Non-isolated design means that the input and output of the power supply are connected directly through the electronic components, and the current can flow between two sections through a circuit. The advantages are high efficiency, small size, ease of design and low cost.

Class I and Class II equipment safety level against electric shock, mainly considering the insulation system of the product:

Class I equipment: this equipment means that there is protection against electric shock through the use of basic insulation, in addition to also providing a protective grounding impedance connected to. When the basic insulation failure, this grounding impedance will withstand the dangerous voltage to ground. That is, Class I switch mode power supply will provide a pair of ground connection terminals.

Class II equipment: This type of equipment not only relies on basic insulation to prevent electric shock protection, but must additionally provide double insulation or reinforced insulation safety protection measures, without grounding or relying on the installation conditions of protection measures. That is, Class II switch mode power supply does not provide a pair of ground connection terminals.

Class 2 is derived from North American UL 1310 Standard for Class 2 Power Units, which mainly refers to the output of product is safe and must be isolated from the input, its single output needs to meet the following basic electrical performance:
a)DC voltage less than 60V in dry and humid environments (42.4V in Canada), and less than 30V in watery environments.
b)Total power <100W
c)Rated output nominal current less than 5A (maximum less than 8A in case of overload)
d)Meets the relevant abnormal test requirements of UL1310.

Class II is derived from the IEC standard or equivalent and refers mainly to the structure or type of insulation against electric shock of the product. It means that the protection against electric shock of the product does not only rely on the basic insulation, but also includes additional safety measures, such as double insulation or reinforced insulation, but no grounding or protection measures that depend on the installation conditions. When the products are designed for / suitable for independent use (outside a luminaire), the products are fully classified as class II and are marked by a double square symbol and if it is only suitable for built-in use (inside a luminaire) it is marked by a double circle symbol.

Class 2 is related to the North American UL standard, which refers to the risk of electric shock or fire from the output; whereas Class II is related to the IEC standard, which refers to safety against electric shock from the input. Note: both are pronounced “class two”.