LED lamps do not light up, LED power supply damage, LED damage and LED circuit damage and other elements account for a certain proportion; in the actual LED lighting application process, because the LED is an electrically sensitive component, to extend the life of the LED, it must be done well LED circuit protection measures, the analysis of LED circuit protection measures is as follows:
Fuse (Tube) Is Used In The Protection Circuit
Because the fuse is one-time, and the response speed is slow, the effect is poor, and the use is troublesome, so the fuse is not suitable for LED lamp products, because LED lamps are mainly used in urban brilliance projects and lighting projects. It requires the LED protection circuit to be very demanding: the protection can be activated immediately when the normal use current is exceeded, the power supply path of the LED is disconnected, so that the LED and the power supply can be protected, and the power supply can be automatically restored after the entire lamp is normal. Does not affect the LED work. The circuit cannot be too complicated, not too big, and the cost is low. Therefore, it is very difficult to implement using a fuse.
Use Transient Voltage Suppression Diodes (TVS For Short)
Transient voltage suppression diode is a high-efficiency protection device in the form of a diode. When its two poles are subjected to a reverse transient high-energy impact, it can immediately reduce the high resistance between its two poles to a low resistance at a speed of 10 minus 12 seconds in a very short time, and absorb up to several kilowatts of surge power. , The voltage between the two poles is clamped to a predetermined voltage value, which effectively protects the precision components in the electronic circuit. Transient voltage suppression diodes have the advantages of fast response time, large transient power, low leakage current, good uniformity of breakdown voltage deviation, easier control of the clamping voltage, no damage limit, and small size.
However, it is not easy to find TVS devices that meet the required voltage value in actual use. The damage of the LED light bead is mainly caused by the overheating inside the chip due to excessive current. TVS can only detect overvoltage but not overcurrent. It is difficult to select a suitable voltage protection point, and this kind of device cannot be produced and it is difficult to use in practice.
Choose Self-Recovery Fuse
Self-recovery 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-like conductive path in the polymer. When the normal working current passes (or the component is at normal ambient temperature), the PTC resettable fuse is in a low resistance state; when there is an abnormal overcurrent in the circuit (or the ambient temperature rises), the large current (or the ambient temperature rises) The generated heat causes the polymer to expand rapidly, which cuts off the conductive path formed by the conductive particles. The PTC resettable fuse is in a high-resistance state; when the overcurrent (over-temperature state) in the circuit disappears, the polymer cools and the volume recovers Normally, the conductive particles re-constitute the conductive path, and the PTC resettable fuse is in the initial low resistance state. In the normal working state, the self-recovering fuse generates very little heat. In the abnormal working state, its heat is very high and the resistance value is very large, which limits the current passing through it, thereby playing a protective role. In the specific circuit, you can choose:
1. Shunt protection. Generally, LED lights are divided into many branches connected in series. We can add a PTC component in front of each branch for protection. The advantage of this method is high accuracy and good protection reliability.
2. Overall protection. Add a PTC component in front of all the light beads to protect the entire 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 still satisfactory.
