The temperature sensor NTC (negative temperature coefficient) has been widely used in LED lamps for over temperature protection. LED lamps, such as high power LED light sources, must adopt a multi wing aluminum radiator. Because of the small space of the LED lamps used for indoor lighting, the problem of heat dissipation is still one of the biggest technical bottlenecks at present. If the LED lamp doesn't work well, it will cause the LED light source to decay early due to overheating. After the LED lamp is turned on, the heat will also be enriched by the hot air rising automatically, which will affect the life of the power supply (Fig. 9). Therefore, when the LED lamp is designed, a NTC can be clung to the side of the LED light source in order to collect the temperature of the lamp in real time. When the temperature of the lamp cup aluminum radiator is raised, the circuit can be used to reduce the output current of the constant current source automatically and make the lamp cool. When the temperature of the aluminum radiator is raised to the limit of the set value, the LED can be automatically shut off when the temperature is limited. Power supply to achieve lamp overtemperature protection, when the temperature is lowered, automatically turn on the lights.