One, why want to protect LED lighting?
White LED lighting, because there are many advantages; is more and more into the daily life of people, its usage is now very great.
It is a new device, has its own characteristics, the use of the. Device white LED belongs to a voltage sensitive. Current shall not exceed 20mA of each LED lamp work too much, more than LED can easily be burned. If LED is normal, and the service life is very long. But the people in the practical use of LED is often bad, why? The fact is that there is no account of the use of LED lamps and on it and the protection circuit.
LED is a semiconductor device, easy in assembly process by static damage. This requires the electrostatic protection in the assembly process. We found that many manufacturers who do not have this concept or don't understand, this is not.
LED lighting in the actual work is based on the 20mA current limit, but often due to various reasons in the use of the resulting current increases, if no protective measures are taken, this current increases over time and amplitude of LED lamp can damage the.
Two. The cause of damage of the LED lamps:
All of a sudden rise 1, power supply voltage. Reasons for the power supply voltage is suddenly increased a lot, such as the power supply quality, improper use and so on the reason or the user may allow the power supply voltage jump.
Short circuit 2, a component or printed lines or other conductor and the formation of local short circuit LED power supply pathway, and increase the voltage of this place.
3, an LED lamp because the quality of their damage so as to form a short circuit, the voltage drop is passed on to other LED.
4, the lamp temperature is too high, so that the characteristics of LED.
5, the lamps and lanterns into the water, water is conductive.
6, in the assembly when no good anti-static work, so that the internal LED lamp has been hurt by the electrostatic. Although the applied normal values of voltage and current, is extremely easy to cause LED damage.
For these reasons will result in LED lighting current increases obviously, and soon LED chip will be burned because of overheating. According to our experience, LED is the most short circuit burned out two, is a small portion of circuit breaker. Each LED about pressure drop of about 3.2V, it burned after this string if circuit breaker LED doesn't shine. If short-circuit the voltage to the other LED, more current caused by other LED, other LED will be faster were burned, and even emergency power supply. It is a small damage it is very easy to cause accident. LED is usually installed in the height, the installation time is not easy, it is more difficult to repair. So the LED protection is the actual demand, but it is not considered, but also the problem a lot of people but there is no way to handle.
Three. Production in Shenzhen LED lamp manufacturers to teach you how to protect the LED lighting:
The protection to LED we first thought of using insurance tube, but the insurance tube is disposable, and the reaction speed is too slow, not only poor results in actual use is also very cumbersome, so the insurance tube is not suitable for now LED lamp products, because the LED lamp is now mainly in the city's glory engineering and lighting engineering. In view of the actual demand, we have done a lot of experiments, and according to the requirements of the project summarizes LED protection circuit to some characteristics, it is very hard to start the protection: immediately beyond the normal current, for LED power supply channel was cut off, so that the power LED and can be protected, in the whole light then automatically resume normal power supply, does not affect the LED work, the key is because it is the civilian products, not the circuit is too complex volume can not be too large, to lower the cost of. These requirements are contradictory, restrict each other, difficult to achieve.
Should first determine the selection of what kind of protection circuit and device.
1, we can choose to use a transient voltage suppression diode (TVS). Transient voltage suppression diode is a diode form of protection device. When the poles by the reverse transient high impact energy, can be 10 of the negative 12 seconds short time speed, high resistance between the poles themselves immediately reduced to low resistance, absorption up to several kilowatts of power surge, the voltage between two bits in a predetermined voltage value, there is effective protection in the circuit of precision components. Transient voltage suppression diode has a fast response time, transient high power, low leakage current, breakdown voltage deviation consistency, the clamp voltage is easy to control, no damage limit, small volume etc..
But in actual use found not very ideal. The first is to find a satisfying TVS requirements of device voltage value is not easy. The TVS device is mainly applied to the thunder and lightning, and above 220V overvoltage absorption, while the voltage of LED lamp is usually 24V or 12V, the voltage values of the TVS products rarely, test not good. At the same time we know: LED light bead damage is mainly because the current Ambassador chip overheating. TVS can detect over-voltage can not detect overcurrent. Over voltage is certainly reason overcurrent, but to select the appropriate voltage protection is difficult to grasp, this device can not be produced would be very difficult to use in practice.
2, we can choose the self recovery fuse. Since the resumption of fuse is also known as the polymer positive temperature thermistor PTC, consisting of a polymer and conductive particles. After special processing, the conductive particles form chains in the polymer conductive pathway. When the normal operating current through (or components are in the normal temperature), since the resumption of PTC