Push–pull converter

For example, in a full-bridge converter, the switches (connected as an H-bridge) alternate the voltage across the supply side of the transformer, causing the transformer to function as it would for AC power and produce a voltage on its output side.

Power MOSFETs are often chosen for this role due to their high current switching capability and their inherently low ON resistance.

The gates or bases of the power transistors are tied via a resistor to one of the supply voltages.

Alternatively, all power transistors can be N-type, which offer around three times the gain of their P-type equivalents.

Then the power transistor is driven in common drain configuration to amplify the current.

Because the transistors operate in an alternating fashion, the device is called a push-pull converter.

On the other hand, if both transistors are in their off state, high voltage peaks appear due to back EMF.

The S-shaped current is needed to improve over the simpler converters and deal efficiently with remanence.