This paper studies the high-efficiency feasibility at wide load in an LLC resonant converter with Synchronous Rectifier (SR) which can achieve zero-voltage-switching (ZVS) turn-on for power management of commercial products. Major efficiency impact is more related to conduction loss is in the secondary side. In order to further improve efficiency of LLC resonant converters, the synchronous rectifier scheme must be used. It is a good solution to improve conduction loss. But, we encounter that a drawback is observed from SR operation. The premature turn-off of SR causes conduction loss and impacts efficiency due to there are parasitic elements from PCB traces and metal-oxide-semiconductors (MOSFETs) package’s stray inductance. Moreover, the signal sensing was affected by sensed voltage and differs from the drop on MOSFET RDS(ON). We propose a good solution to use a compensated sensing circuit on the synchronous rectifier. The solution could be prevented from premature turn-off and not really related to current flowing through the MOSFET’s body diode. Therefore, minimizing turn-on and turn-off delay is a good way to optimize the efficiency. A prototype with 12 V 200 W output was built to verify the theoretical analysis.