Power Sources and Supplies: World Class Designs

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Chapter 10

We can ask—where does the leakage inductance really reside? Most of it is inside the

primary winding of the transformer

, though some of it lies in the PCB trace sections and

transformer terminations, especially with those associated with the secondary winding, as

we will see below.

10.1.6 Zener Clamp Dissipation

If we burn the energy in the leakage, it is important to know how this affects the effi ciency.

It is sometimes intuitively felt the energy dissipated every cycle is just 1/2  L

LKP

I

PK

2

,

where I

PK

is the peak switch current, and L

LKP

is the primary-side leakage. That certainly

is the ...