With the gradual development of LED lighting, lighting engineering in the auxiliary lighting and other public places, LED lighting gradually replaced some of the traditional light source products. In the use of commercial applications for a long time, LED lamps quickly become the new darling of the market. LED if it is used normally, its life is very long. But people in the actual use of LED is often bad, in fact, because it does not take into account the use of LED features and due protection. LED damage caused by the reasons: 1 electrostatic damage: because the LED is a very sensitive to the electrostatic semiconductor optoelectronic devices, 3KV static enough to cause fatal damage. 2 overcurrent damage: LED has its specific working current in the practical work, and small range but are often due to various reasons in the use of the resulting current increases, this current increases over time and amplitude after LED will cause damage. 3 overvoltage damage: power supply voltage suddenly increased, resulting in damage to the back-end circuit. These reasons will cause a significant increase in LED current, LED chips will be burned because of overheating. Part of the LED burn down is the short circuit, part of the circuit is broken. Each LED about 3V pressure drop, it burned after the break if the string LED will not shine. If the short circuit voltage is transferred to the other LED, resulting in other LED greater current, other LED will be faster burned, and even critical power. Very small damage can easily lead to major accidents. The following is the LED protection program. LED overvoltage and overcurrent protection scheme: Selection: TVS according to the requirements of the protection of the power to choose PPTC according to the size of the circuit in the choice of working current
O.C.P is designed for LED open circuit protection design PLED06B open circuit protection device protection principle: LED input with high voltage pulse will lead to the back-end chip and the LED lamp is damaged, and the TVS of the high voltage pulse transient suppression diodes can absorb and clamp, the range of voltage is reduced to the back-end circuit can bear, thus eliminating the interference by the end of the input. PPTC is a self recovery fuse, can prevent the excessive current to LED damage, when there is a large current through the PPTC at the moment into a high impedance state to current decreases, when the large current after the disappearance of the resistance can be restored to its original parameters, will not affect the normal operation of the circuit. O.C.P type semiconductor overvoltage protection device, when the lamp ends have electrostatic and overvoltage can be instantly absorbed and clamped, reduce voltage, and when the LED circuit is damaged, the damaged LED lamp current cannot flow, while the power supply voltage are added to the O.C.P, the voltage across O.C.P soon reached the switching voltage the O.C.P will then start working voltage is reduced to about 1V, current from O.C.P after flowing through other LED beads, beads and other light up.