State-of-the-art multiple outputs high brightness (HB) LED driving technology

In high power HB LED lighting applications, low output voltage LED drivers are preferred due to its low voltage stress and safety requirement, high reliability and safety requirements. However, most LED modules are packaged in low power module, such as 1W and 3W modules. Therefore, more LED strings are required to reduce the forward voltage drop. Since the currents in different LED strings should be kept in same in order to keep same luminance, current sharing techniques must be introduced in multi-output drivers. This paper reviews and compares the state of the art multi-output driving techniques and classified these solutions according to balancing principles.