Experimental results

AN2872

16/23

Doc ID 15305 Rev 1

4.3

Efficiency

The efficiency of the converter depends strictly on the input voltage. The efficiency of the

tested board is about 65% full load at nominal EU voltage. Complete measurement of the

efficiency is shown in Figure 10.

Figure 10.

Efficiency of the converter

The efficiency can be slightly improved using inductors with reduced resistance and low

ESR input and output capacitors.

4.4

MOSFET voltage stress

A sufficient margin between the maximum drain voltage and the real maximum operating

voltage level guarantees good reliability of the converter. The drain voltage (CH1) and

inductor current (CH2) is displayed in Figure 11 at full load (150 mA). The maximum voltage

drop between the drain and source is 700 V. The margin is, at worst conditions, 100 V.

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

0

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100

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90 VAC

120 VAC

230 VAC

400 VAC

500 VAC

AM00365

Eff. (%)

IOUT (mA)