EnglishViews: 0 Author: Site Editor Publish Time: 2021-05-10 Origin: Site
After the LED light bar is turned on, part of the lamp bead is not bright, basically you can judge that the light bar bead is damaged. A damaged light bar bead is usually visible to the naked eye - a black spot on its surface indicates that it has been burned. Sometimes the light bar bead is first in series and then in parallel, so a light bar bead loss, will cause a light bar bead not bright. Or when the light bead flickers constantly, we can replace the led light bar.
Here is the content list:
l The cause of led light bar damage
l Transient overcurrent event
l Electrostatic discharge event
The failure of led light bars comes from the failure of power supply and drive, and the failure of LED devices themselves. LED power and drive damage is usually caused by input power overshock (EOS) and load side break fault. The electric shock of the input power supply often causes damage to the driver chip in the drive circuit, as well as the breakdown of passive components such as capacitors. The short circuit fault at the load end may cause the overcurrent drive of the drive circuit, and the drive circuit may be damaged by a short circuit or overheating caused by a short circuit fault.
Transient overcurrent event refers to the current flowing through the LED exceeds the maximum rated current in the LED technical data manual, which may be directly generated by large current or indirectly generated by high voltage, such as transient lightning strike, transient switching noise of switching power supply, power grid fluctuation and other overvoltage events caused by overcurrent. These events are transient and have very short duration, which is commonly referred to as a spike, e.g., "current spike", "voltage spike". Other conditions that can cause transient overcurrent events include LED power on, or transient overcurrent during live plug and unplug.
For LED lighting in automobiles, the transient load surge impact of ISO7637-2 is an important threat to its normal operation.
The failure mode of LEDs subjected to electrical shock is not fixed, but it usually results in welding wire damage, as shown in Figure 1. This damage is usually caused by a very large transient overcurrent. In addition to causing the welding wire to burn, it may also cause damage to other parts near the welding wire, such as sealing material.
Electrostatic discharge (ESD) damage is one of the most common transient overvoltage hazards in the manufacturing, transportation and application of highly integrated semiconductor devices at present, and LED lighting system must meet the IEC61000-4-2 standard "human body ESD mode" 8kV contact discharge, in order to prevent the system may lead to overelectric shock failure in the electrostatic discharge.
LEDPN junction array performance will be reduced or damaged. The internal failure of the LED chip caused by the ESD event discharge path may be only partial functional damage, but it will also lead to permanent damage of the LED.
In general, when the led light bar is damaged, it should be replaced. The most obvious thing is that the bead doesn't light up or blinks. At the same time, we also need to know the cause of led light bar damage, so that we can replace it better.
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