AN2439

Board description

13/20

1.6

Transformer

The details of the transformer used are listed below.

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Electrical characteristics

–

–

●

Magnetic core

–

Material: N67

–Type: ETD29

–

Air gap:

≈ 0.2 mm

Figure 8 describes the used and suggested placing of the windings.

Figure 8.

Transformer winding placing

1.7

Board tests

The tests performed aim to evaluate the converter behavior in terms of efficiency, safe

operating area of the devices, and line and load regulation.

1.8

Start-up tests

In a flyback converter the most critical conditions for the mains switch (when no abnormal

event occurs), in terms of maximum drain current and of maximum drain voltage, are during

the start-up phase. The max values for drain voltage and current were measured in both full

Table 6.

Winding size

Winding

Number of turns

Wire size

Primary winding

46

AWG26

Secondary winding

4

AWG26X4

Auxiliary winding

10

AWG40

½ Primary Winding

½ Primary Winding

Secondary Winding

Auxiliary Winding

Insulation