An apparatus includes: a power supply circuit including at least a first stage having a push-pull circuit topology, the first stage including at least one transformer that isolates a primary side of the first stage from a secondary side of the first stage; a clamp circuit coupled to a center tap of the transformer, the clamp circuit including a first element that stores energy, and a second element that controls a flow of current between the center tap of the transformer and the first element; and a control module receiving power from the clamp circuit. The control module is configured to provide control signals to one or more elements of the power supply circuit.