An integrated and isolated onboard charger for plug-in electric vehicles, includes an ac-dc converter and a dual-output dc-dc resonant converter, for both HV traction batteries and LV loads. In addition, the integrated and isolated onboard charger may be configured as unidirectional or bidirectional, and is capable of delivering power from HV traction batteries to the grid for vehicle-to-grid (V2G) applications. To increase the power density of the converter, the dual-output DC-DC resonant converter may combine magnetic components of resonant networks into a single three-winding electromagnetically integrated transformer (EMIT). The resonant converter may be configured as a half-bridge topology with split capacitors as the resonant network components to further reduce the size of converter. The integrated charger may be configured for various operating modes, including grid to vehicle (G2V), vehicle to grid (V2G) and high voltage to low voltage, HV-to-LV (H2L) charging.