Application circuit description

AN2252

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Figure 9.

PCB layout

Figure 10. shows the converter.

Figure 10.

Picture of the converter

2.3.1

Evaluation and measurements

The converter was specially designed to have a high power efficiency. Figure 11. shows that

the converter’s output efficiency depends on the input voltage (two marginal values are

taken as example). Since the flyback voltage is not higher than the maximum input voltage,

for some values of the input voltage the conditions under which the converter operates in

ZVS mode are not met and the primary switch turn-on is no longer lossless. This is clearly

seen in Figure 11., where there is a difference in efficiency according to Vin in the medium

and low output power regions. At high output powers, however, the primary switch

conduction loss prevail over the turn-on loss.