This article first introduces the basic concept of LED circuit, LED damage causes and LED circuit protection methods to share, first to understand the basic concept of LED circuit and then analyze the causes of LED damage, and finally put forward the protection method of LED circuit. The protection of LED circuit can be realized by using fuse and suppression diode. I hope this article can bring you effective help

Basic concept of LED circuit
    LED(light-emitting Diode Chinese meaning Light Emitting diode) is a kind of semiconductor that can convert electrical energy into visible light, it changes the principle of incandescent tungsten filament light and energy-saving lamp three-base powder light, and uses electric field light. According to analysis, the characteristics of LED are very obvious, long life, high light efficiency, no radiation and low power consumption. The spectrum of LED is almost all concentrated in the visible band, and its luminous efficiency can reach 80 to 90%. Compared LED with ordinary incandescent lamps, spiral energy-saving lamps and T5 three-color fluorescent lamps, the results show that: The light efficiency of ordinary incandescent lamp is 12lm/W, the life is less than 2000 hours, the light efficiency of spiral energy-saving lamp is 60lm/W, the life is less than 8000 hours, T5 fluorescent lamp is 96lm/W, the life is about 10000 hours, and the diameter of 5 mm white LED is 20~28lm/W, the life can be greater than 100000 hours. Some people also predict that the future LED life limit will be infinite.
    High power, refers to the luminous power rate is large, generally refers to 0.5W,1W3W5W or higher. The light intensity and lumen are larger than the small power, but the same heat dissipation is also large, and now the high power is a single application, plus a large heat sink. The small power is generally about 0.06W. Plugins and piranha, etc. Now LED flashlight is generally used with low power, light does not scatter, depending on the LED luminous Angle, there is a large Angle of small Angle, small Angle does not scatter, large Angle to scatter.
    And some LED in the use of various reasons to increase the current, this time if you do not take protective measures, then this increase in the current more than a certain time and amplitude after the LED will be damaged. So let's understand the specific causes of LED damage.

The main reasons for lED damage are:
    1. Sudden rise in voltage.
    2. The short circuit of a component or printed line or other wire forms a local short circuit of the LED power supply path, which increases the voltage in this place.
    3. The LED is damaged for its own quality reasons and thus forms a short circuit, and its original voltage drop is transferred to other leds.
    4. The internal temperature is too high, which makes the characteristics of the LED deteriorate.
    5. There is water inside, which is conductive.
    6. When matching, there is no good anti-static work, so that the interior of the LED has been damaged by static electricity. Although the normal voltage and current values are applied, it is also very easy to cause damage to the LED.
    Understand the above factors that cause LED damage. So, how should I protect the LED circuit?

The method of protecting LED circuit is as follows:
1. Fuse (tube) in LED circuit
    Because the fuse is disposable, and the reaction speed is slow, the effect is poor, and the use of trouble, the fuse is not suitable for LED lights in the finished product, because LED lights are now mainly in the city's luster engineering and lighting engineering. It requires the LED protection circuit to be very harsh: in excess of the normal use of current can immediately start the protection, so that the LED power supply path is disconnected, so that the LED and power can be protected, and the power can be automatically restored after the whole light is normal, without affecting the LED work. The circuit should not be too complex, the volume should not be too large, and the cost should be low. So it's very difficult to do that with fuses.
2. Transient Voltage suppression diode (TVS)    
Transient voltage suppression diode is a kind of high performance protection device in the form of diode. When its poles are affected by the reverse transient high energy impact, it can reduce the high resistance between its poles to low resistance at a very short time speed of 10 to the minus 12 seconds, absorb up to several kilowatts of surge power, and the voltage clamp between the poles at a predetermined voltage value, effectively protecting the precision components in the electronic circuit. Transient voltage suppression diode has the advantages of fast response time, large transient power, low leakage current, good consistency of breakdown voltage deviation, easy control of clamp voltage, no damage limit, small size and so on.
    However, in actual use, it is not easy to find TVS devices that meet the required voltage values. The damage of LED light beads is mainly caused by the overheating of the internal chip. TVS can only detect overvoltage but not overcurrent. To choose the right voltage protection point is difficult to master, this device can not be produced and it is difficult to use in practice.
3. Select a self-restoring fuse
    自Self-restoring fuse, also known as polymer positive temperature thermistor PTC, is composed of polymer and conductive particles. After special processing, the conductive particles form a chain conductive path in the polymer. When the normal working current passes through (or the component is at the normal ambient temperature), the PTC self-restoring fuse is in a low resistance state; When there is an abnormal overcurrent in the circuit (or the ambient temperature rises), the heat generated by the large current (or the ambient temperature rises) makes the polymer expand rapidly, which cuts off the conductive path composed of conductive particles, and the PTC self-restoring fuse shows a high resistance state; When the overcurrent (overtemperature state) in the circuit disappears, the polymer cools, the volume returns to normal, in which the conductive particles re-constitute the conductive path, and the PTC self-restoring fuse shows the initial low resistance state. In the normal working state, the heat of the self-restoring fuse is very small, and in the abnormal working state, its high heat resistance is very large, which limits the current through it, thus playing a protective role.

In the specific circuit, you can choose:
       ① Branch protection. General LED lights are divided into many serial branches. We can add a PTC component in front of each branch for protection. The advantages of this method are high accuracy and good reliability of protection.
    ② Overall protection. A PTC component is attached to the front of all the light beads to protect the whole lamp. The advantage of this method is that it is simple and does not take up volume. For civilian products, the results of this protection in actual use are satisfactory.
    This paper first introduces the basic concept of LED circuit, LED damage causes and LED circuit protection methods to share, first to understand the basic concept of LED circuit and then analyze the causes of LED damage, and finally put forward the protection method of LED circuit. The protection of LED circuit can be realized by using fuse and suppression diode. I hope this article can bring you effective help.