A single-ended primary-inductor converter, SEPIC, circuit having at least a circuit input node and a circuit common node the converter circuit comprising: an inductor; a first coupling capacitor; an isolation transformer having a transformer primary and a transformer secondary, the transformer primary having a first primary terminal and a second primary terminal, the transformer secondary having a first secondary terminal and a second secondary terminal; a controllable switch configured to selectively operate in an ON state, in which current will flow through the controllable switch, and an OFF state, in which current will not flow through the controllable switch; a second coupling capacitor; a clamp diode; a first output node; a second output node; an output diode; an output capacitor electrically connected between the first output node and the second output node; and a load electrically connected in parallel with the output capacitor, wherein: the inductor is electrically connected in series between the circuit input node and the first coupling capacitor, the first coupling capacitor is connected in series between the inductor and the first primary terminal, the controllable switch is electrically connected in series between an internal circuit node and the circuit common node, the internal circuit node located between the inductor and the first coupling capacitor, the second coupling capacitor is electrically connected in series between the second primary terminal and the circuit common node, the clamp diode is electrically connected in series between the internal circuit node and the second primary terminal, the output diode is electrically connected between the first secondary terminal and the first output node, the second output node is electrically connected to the second secondary terminal, and characterized in that: when the controllable switch is in the OFF state and the clamp diode is forward biased i) the isolation transformer and first coupling capacitor are electrically coupled in parallel with each other and with the load and ii) the second coupling capacitor is not electrically coupled in parallel with the load. an inductor; a first coupling capacitor; an isolation transformer having a transformer primary and a transformer secondary, the transformer primary having a first primary terminal and a second primary terminal, the transformer secondary having a first secondary terminal and a second secondary terminal; a controllable switch configured to selectively operate in an ON state, in which current will flow through the controllable switch, and an OFF state, in which current will not flow through the controllable switch; a second coupling capacitor; a clamp diode; a first output node; a second output node; an output diode; an output capacitor electrically connected between the first output node and the second output node; and a load electrically connected in parallel with the output capacitor, wherein: the inductor is electrically connected in series between the circuit input node and the first coupling capacitor, the first coupling capacitor is connected in series between the inductor and the first primary terminal, the controllable switch is electrically connected in series between an internal circuit node and the circuit common node, the internal circuit node located between the inductor and the first coupling capacitor, the second coupling capacitor is electrically connected in series between the second primary terminal and the circuit common node, the clamp diode is electrically connected in series between the internal circuit node and the second primary terminal, the output diode is electrically connected between the first secondary terminal and the first output node, the second output node is electrically connected to the second secondary terminal, and characterized in that: when the controllable switch is in the OFF state and the clamp diode is forward biased i) the isolation transformer and first coupling capacitor are electrically coupled in parallel with each other and with the load and ii) the second coupling capacitor is not electrically coupled in parallel with the load. the inductor is electrically connected in series between the circuit input node and the first coupling capacitor, the first coupling capacitor is connected in series between the inductor and the first primary terminal, the controllable switch is electrically connected in series between an internal circuit node and the circuit common node, the internal circuit node located between the inductor and the first coupling capacitor, the second coupling capacitor is electrically connected in series between the second primary terminal and the circuit common node, the clamp diode is electrically connected in series between the internal circuit node and the second primary terminal, the output diode is electrically connected between the first secondary terminal and the first output node, the second output node is electrically connected to the second secondary terminal, and characterized in that: when the controllable switch is in the OFF state and the clamp diode is forward biased i) the isolation transformer and first coupling capacitor are electrically coupled in parallel with each other and with the load and ii) the second coupling capacitor is not electrically coupled in parallel with the load.