The load side of the LED lamp is generally composed of a number of LED strings in parallel, and its working voltage Vo=Vf*Ns, where Ns represents the number of LEDs connected in series. The Vf of the LED changes with temperature. Generally, at a constant current, the Vf becomes lower at high temperatures, and Vf becomes higher at low temperatures. Therefore, the LED lamp load working voltage corresponds to VoL at high temperature, and the LED lamp load working voltage corresponds to VoH at low temperature. When selecting the led light driver, it is necessary to consider that the output voltage range of the led light driver is greater than VoL~VoH.

If the maximum output voltage of the selected led dimmable drivers is lower than VoH, the maximum power of the lamp may not reach the actual power required at low temperatures. If the minimum voltage of the selected led dimmable drivers  is higher than VoL, the output of the drive power may exceed the working temperature at high temperatures. Range, work is unstable, lamps will flicker, etc.

However, considering the overall cost and efficiency, it is impossible to blindly pursue the ultra-wide output voltage range of the led dimmable drivers: because the led dimmable drivers voltage is only in a certain range, the led dimmable drivers efficiency is the highest. When the range is exceeded, the efficiency and power factor (PF) will deteriorate. At the same time, the design of the output voltage range of the driving led dimmable drivers is too wide, which will lead to higher costs and the efficiency cannot be optimized.