The importance of the LED wire harness for LED power supply and drive circuit protection

With the continuous development of LED technology, domestic LED applications have also matured, from indicator lights, signal lights, display screens, landscape lighting, to indoor and outdoor lighting, reminding everyone, when using LED products, pay attention to LED power supply and drive Circuit protection.

Since the LED power supply and the driving circuit are easily damaged by over-current shock and short-circuit fault, the protection measures of various fault states should be fully considered in the design of the driving circuit to improve the reliability of the circuit and thereby reduce the repair rate.

Although many high-end LED driver devices are gradually integrated with protection functions such as overcurrent and overheating, in many cases, especially for overheat protection, discrete component solutions are still needed as a synergistic protection scheme to make lamps more reliable and more reliable. Long life.

PPTC refers to a polymer positive temperature thermistor, which is composed of a 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 PPTC is in a low resistance state. When an abnormal overcurrent is passed through the circuit (or the ambient temperature rises), the heat generated by the large current (or an increase in the ambient temperature) causes the polymer to rapidly expand, cutting off the conductive path formed by the conductive particles, and the PPTC is high-resistance. status. When the overcurrent (overtemperature condition) in the circuit is removed, the polymer cools and the volume returns to normal. The conductive particles reconstitute the conductive path, and the PPTC is in an initial low resistance state. The PPTC is small in size, low in cost, and can be used repeatedly to realize automatic start and automatic recovery of circuit protection.

In LED lighting, there are different types of overheat protection depending on the application of the luminaire, which is usually divided into two types. One way is to immediately initiate shutdown protection at the specified temperature, which is typically applied to road traffic lights. Another way is to start protection at a certain temperature and drive down current. This protection is usually applied to indoor lighting and road lighting.