CET Technology

CET Push-Pull Transformers

CET Push-Pull Transformers

There are many benefits of the push-pull topology, but low EMI, efficiency and stable current top the list. Unlike typical flyback and forward topologies, the push-pull topology offers high efficiency at a stable input and output current. Plus, the push-pull has a lower ripple current, which contributes to the higher efficiencies and consequently, a smaller footprint.

The current is brought into the primary center tap and is routed alternately out through the top of the primary, then out through the bottom of the primary.  This action creates alternating magnetic fields within the core that change polarity every half cycle.  This is what gives the transformer its name – push and then pull – push-pull!

The push-pull uses transformer action to transfer power from the primary to the secondary, as opposed to other topologies like the flyback which store and then transfer. A disadvantage would be the possibility of “flux walking”. If flux is not equally generated in equal amounts on each polarity cycle it can have the effect of “walking” the flux in the core toward one end causing core saturation.