The primary side of an LLC converter includes a primary-side switch network connected to an LLC network having a first winding of an isolation transformer. The secondary side includes a secondary-side switch network having first and second rectification branches coupled to different tap points of a second winding of the isolation transformer. Switching of the secondary-side switch network is controlled based on a drive signal and a current sense signal indicative of current in the rectification branches. For a first part of each switching cycle, discontinuous conduction mode (DCM) is detected based on a falling edge of the current sense signal occurring before a falling edge of the drive signal for the first rectification branch. For a second part of each switching cycle, DCM is detected based on the falling edge of the current sense signal occurring before a falling edge of the drive signal for the second rectification branch.