實用led熱設(shè)計

　　添加一個簡單的熱反饋保護(hù)電路將給設(shè)計師安心，并保證在所有操作條件和溫度下LED壽命長。

　　在過去的幾年中，高亮度發(fā)光二極管（LED）已從一個利基產(chǎn)品，作為一個昂貴的設(shè)計師聚光燈到一個有用的通用燈，系統(tǒng)效率超過100流明/瓦特和壽命超過50000小時，極大地發(fā)展。

　　然而，大功率LED技術(shù)的引入推動了熱管理問題回到照明設(shè)計的前沿。像所有的半導(dǎo)體一樣，LED也不能太熱，否則它們的長壽將受到不利影響。在50000℃時，連接溫度為25°C的LED僅能存活175秒，連接溫度為125°C的一半，LED僅能存活100小時。

　　Although the efficiency of a high-power LED is around six times better than a standard incandescent light bulb， a significant amount of the electrical energy flowing through the device is still converted into heat. Whereas the waste heat from an Edison bulb is mostly radiated away as infrared energy， the waste heat from an LED must be conducted away through a heat sink. Thermal management and the consideration of the effects of high environmental temperatures must thus be addressed right at the start of the design phase of a solid state lighting source.

　　The factors affecting the effectiveness of a heat sink are the temperature difference between the heat source and ambient， the amount of heat generated （LED power）， and the thermal resistance. The relationship of the factors can be expressed as an equation：