2. What are the most common LED driving methods? What are its advantages and disadvantages?
2. What are the most common LED driving methods? What are its advantages and disadvantages?
Table 2: LED driving methods and PSU selection
Driving method & PSU selection
Features
Advantage/disadvantage
Direct drive Use C.C. power supply
Voltage at the output of the power supply will equal to the total LED VF. IF will be affected by temperature change.
○ Lowest price ○ Highest efficiency X Uneven current for paralleled LED strips X Uneven brightness for aralleled LED strips X Quick decline in luminance. Short LED lifetime.
With series resistor Both C.V. or C.C. can be used
Voltage exceeding total LED VF will appear across the series resistor. Moderate IF stability.
○ Low price. With additional resistor cost. X Lowest efficiency. Due to resistor power loss.
With driver IC Use C.V. power supply
IC automatically limits IF to each LED strip. High IF stability.
○ Slow decline in luminance. Longest LED lifetime. X Low efficiency. X Most expensive