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Causes of failure of LED drive
Nov 26, 2016

Basically it can be said that the main function of the LED driver is to convert the input AC voltage source to the output voltage can be increased with LED

Vf (positive conduction voltage drop change current source. As the key part of LED lighting, the quality of LED driver directly affects the reliability and stability of the whole lamp. This article from the LED drive and other related technology and customer application experience, finishing and analysis of lighting design and application of many of the failure:

1, without considering the change range of LED lamp Vf lamp, led to low efficiency, even instability

LED lamp load end, usually by a number of series parallel LED series, its working voltage Vo=Vf*Ns, which Ns said LED series number. Vf LED changes with temperature, under normal circumstances, in a constant current, high temperature when the Vf is low, low temperature when the Vf becomes high. Therefore, the high temperature LED lamp load operating voltage corresponding to VoL, low temperature when the LED lamp load operating voltage corresponding to VoH. When selecting the LED driver, the output voltage range of the driver should be considered to be more than VoL~VoH.

If the LED driver selected the maximum output voltage is lower than VoH, may lead to the maximum power at low temperature lighting is not up to the actual power required, if the LED driver selected the lowest voltage higher than VoL, the output may drive beyond the scope of work is high, the work is not stable, the lamp will be flashing etc..

However, the comprehensive cost and efficiency considerations, can not blindly pursue LED drive over wide output voltage range: because the drive voltage is only in a certain range, the drive efficiency is the highest. Over range efficiency, power factor (PF) will be poor, while the drive output voltage range is too wide, resulting in increased costs, the efficiency can not be optimized.

2, without taking into account the power margin and reduce the amount required

Under normal circumstances, the nominal power of the LED driver is the data measured under the condition of the rated environment and the rated voltage. Considering the different customers have different applications, most of the LED drive power supply will provide in their product specifications on derating curve (common load vs temperature derating curve and load vs input voltage derating curve).