Driving methods are mainly divided into two categories: constant current (CC) and constant voltage (CV). A constant current drive circuit outputs a constant current, while the output DC voltage varies within a certain range depending on the load resistance. Constant current circuits are not afraid of short circuits, but a completely open circuit is strictly prohibited. Constant current drive circuits are ideal for driving LEDs, but they are relatively expensive. Compared to overall constant current, individual constant current drives have more disadvantages and are more expensive, but they truly protect LEDs and extend their lifespan, making individual constant current the future trend.
Core electrical parameters include output type, output current and accuracy, output voltage range, output power, input voltage range, efficiency and power factor, and operating temperature range. Output types are either constant voltage (CV) or constant current (CC), with current accuracy of ±3% to ±5%. The output power calculation formula is: Output Voltage (V) × Output Current (A) = Power (W). The commonly used input voltage range is AC 100-240V wide voltage, power factor (PF) value >0.9, conversion efficiency >85%. The operating temperature range is usually -30℃ ~ +70℃. New applications also require drivers with low bandgap reference and PWM brightness adjustment functions. According to the circuit structure, the main types include resistor and capacitor step-down, conventional transformer step-down, electronic transformer step-down, RCC step-down switching power supply, PWM control switching power supply, etc. PWM control switching power supply has extremely high power efficiency, generally 80% to 90%, and stable output voltage and current. Generally, this type of circuit has complete protection measures and is a high reliability power supply. The key protection functions that LED constant current drive power supply should have include short circuit protection (SCP), overload protection (OLP), and overvoltage protection (OVP). Other protection functions may include reverse phase protection, impact load protection, etc. Common product certification marks include CCC, CE, UL, TUV, etc. [6]. CCC certification for LED drivers is a mandatory market access requirement and an important part of China's mandatory product certification system. Products such as stand-alone LED drivers and built-in LED control devices must be certified and affixed with the CCC mark before they can be sold, imported, or used in the Chinese market.
