Followed by stable voltage ability is poor, cannot be guaranteed through the LED current is less than its normal work requirements, design products will reduce the voltage on both ends of the LED is used to power drive, this is to reduce the cost of the LED brightness. Driven by way of resistance and capacitance step-down LED, LED brightness cannot be stable, when the low power supply voltage, the brightness of LED dimming, power supply voltage is high, the brightness of the LED lights. Resistance, capacitance step-down method drive LED the biggest advantage is low cost.
According to the characteristic of LED current, voltage changes, driven by constant voltage LED is feasible, although commonly used voltage stabilizing circuit, voltage regulation precision is not enough and the disadvantage of poor steady flow ability, but on the application of some products may be too precise design, its advantage is still cannot replace other drive way.
Using constant current drive mode, is ideal LED drive mode, it can avoid the LED forward voltage caused by the change of the current change, at the same time that the brightness of the LED constant current stability. So many manufacturers choose drive LED constant current way. There is a way of the LED driver is feasible, it is not constant voltage, constant current, but through the design of the circuit, when the LED forward voltage rises, reduce drive current, ensure the safety of LED products. Of course forward voltage rise only in LED, too high will damage the LED.
Ideal is LED drive mode with constant voltage and constant current. But the cost of the drive. Actually all have advantages and disadvantages, each drive way according to the requirements of LED products and applications, the reasonable choice of LED drive mode, precise design drive power become the key.