1. Use a fuse (tube) in the protection circuit
Because fuses are disposable, slow in response, poor in function, and laborious in operation, fuses are not suitable for use in LED lighting products, because LED lights are now mainly used in urban glory projects and lighting projects.
It requires the LED lamp bead protection circuit to be very strict: it can immediately claim protection when the normal operating current is exceeded, so that the power supply path of the LED is disconnected, so that both the LED and the power supply can be protected, and it can be automatically protected after the entire lamp is normal. Rehabilitation power supply does not affect LED operations. The circuit should not be too messy, not too big, and the cost is even lower. Therefore, it is very difficult to end the method of choosing a fuse.
2. Deep UV LED manufacturers use transient voltage suppression diodes (TVS for short)
Transient voltage suppression diode is a high-efficiency protection device based on diode method. When its north and south poles are subjected to a reverse transient high-energy impact, it can immediately reduce the high resistance between the north and south poles to a low resistance at a speed of 10 minus 12 seconds, and absorb up to several kilowatts. The surge power clamps the voltage between the north and south poles to a predetermined voltage value, which effectively protects the fine components in the electronic circuit.
Transient voltage suppression diodes have the advantages of fast care time, large transient power, low leakage current, good breakdown voltage error consistency, easier control of the clamping voltage, no damage limit, and small size.
However, it is not easy to find a TVS device that meets the required voltage value in practice. 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 an appropriate voltage protection point, and this kind of device cannot be produced and it is difficult to use it in practice.
3. Choose a self-healing fuse
Self-healing 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 operating current passes (or the component is at normal ambient temperature), the PTC self-healing fuse is in a low resistance condition;
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) activates the expansion of the polymer, which also cuts off the conductive path formed by the conductive particles, PTC The self-healing fuse is high resistance;
