High-brightness， high-power LEDs （HBLEDs）， like any other semiconductor device， generate heat. Since it is well known that high temperatures can significantly shorten an HBLED‘s lifetime as well as negatively impact brightness， temperature control is required. However， in order to control the temperature， a designer first needs to determine how to monitor the temperature of the LED die， and that is precisely the role of a negative temperature coefficient （NTC） thermistor in an LED lighting system.

　　Different temperature sensing devices， including diodes， on-chip sensors， positive temperature coefficient （PTC） thermistors， and resistance temperature detectors （RTDs）， can be used in LED lighting applications to protect the HBLED from overheating. However， NTC thermistors are often the preferred choice for temperature sensing and control in many of these applications， primarily because of their small package sizes and attractive price/performance ratios.