The range of variation of the LED lamp bead Vf is not considered, resulting in low efficiency of the lamp and even unstable operation.
The load end of an LED luminaire is generally composed of a plurality of LED strings connected in parallel, and its operating voltage Vo = Vf * Ns, where Ns represents the number of LEDs connected in series. Therefore, the operating voltage of the LED lamp load corresponds to VoL at high temperature, and the working voltage of the LED lamp at low temperature corresponds to VoH. In the LED driver, you need to consider the driver output voltage range is greater than VoL. ~VoH.
If the maximum output voltage of the replacement LED driver is lower than VoH, the maximum power of the luminaire may not reach the actual power required at low temperature. If the minimum voltage of the replacement LED driver is higher than VoL, the driver output may exceed the working range at high temperature, and work. Unstable, the lamp will flash and so on.
However, considering the overall cost and efficiency, we can't blindly pursue the ultra-wide output voltage range of LED drivers: because the driver voltage is only in a certain interval, the driver efficiency is the highest. After the range is exceeded, the power factor (PF) will be worse, and the driver output voltage range is designed to be too wide, resulting in increased cost and inefficient optimization