A novel two stage LED driver compatible with electronic transformers for MR16 lamp

In this paper, a novel two stage LED driver scheme used in the MR16 system is proposed. A peak current control boost converter is adopted in the front stage to avoid the capacitive load problem. By adding a low pass filter (LPF) unit in the front stage control loop, the inrush current problem is solved. The proposed approach is well compatible with the electronic transformers (ETs). The second stage can be a buck or buck-boost converter depending on the output voltage of LED lamps. The effect of the dc link voltage ripple is eliminated by adding the second stage circuit. The proposed LED driver presents a considerably good compatibility with different kinds of electronic transformers. Moreover multi LED drivers can be parallel in the system without the over current problem. Furthermore, the power factor can be significantly improved with the proposed two stage scheme. 3W LED drivers are built and tested. The experimental results verify the theoretical analysis.