**Part Number:** SN6501

Hello guys,

I want to use SN6501 with transformer 750313638 in my application as it is just described in your data sheet of the component. This configuration has an efficiency of 40% when the load current is 10mA. I want to understand the efficiency described in your datasheet. Does that mean, that 60% of input power to the circuit is an ohmic loss? What is the most dominant part of this ohmic loss? Is it the core losses of the transformer?

Furthermore, I am struggling with understanding the way how magnetizing current (clearly reactive) behaves with push-pull configuration. During one half of a switching cycle the core flux is energized with the energy contained in the magnetization inductance. Then in the other half of the switching cycle, this energy has to be emptied from the core and the core shall be reset. Then with an opposing magnetization current the same amout of magnetic energy has to be built up in the flux. What I don't understand, where does this magnetic energy go during a switching cycle? My assumption is that the energy = 0.5*Lm*Im*Im, where Lm is magnetizing inductance, Im is magnetizing current.

Is this energy pushed back to the voltage supply's capacitance in every switching cycle? Is this something that appears as a reactive power loss in your Efficiency calculation for the SN6501?

Thanks for the answers upfront.

Tamas