Switching Power Supplies A - Z

Chapter 3

In brief, the secondary-side leakage has created much the same effect as a primary-side

leakage.

When both primary- and secondary-side leakages are present, we can find the effective

primary-side leakage (as seen by the switch and zener clamp) as

L

LK

= L

LKP

+ n

2

L

LKS

So, like any other reactive element, the secondary-side leakage also reflects onto the primary

side according to the square of the turns ratio, where it adds up in series with any

primary-side leakage present.

For a given V

OR

, if the output voltage is “low” (for example 5 V or 3.3 V), the turns ratio is

much greater. Therefore, if the chosen V

OR

is very high, the reflected secondary-side ...