UM0984

Board description

Doc ID 17812 Rev 2

11/25

Figure 4.

Transformer construction

3.4

Layout

The layout of the PCB is based on a single-sided FR4, with 35 µm thickness. The size of the

PCB is 32 x 90 mm. The distance between the primary and secondary side is higher than

8 mm, respecting the safety requirements for all standard applications. The layout of the

PCB is provided in Figure 5.

The layout was designed with respect to the following rules to achieve stable operation,

good efficiency and reduce EMI noise.

●

The power HF tracks are wide and short:

–

Transformer to IC1

–

Transformer to C13

–

IC1 to C13

–

Transformer to C8

–

C8 to D3

–

Transformer to D3

–

Peak clamp loop

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The power and signal GND of VIPER26LD are separated and connected only in one

point close to the source pins

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The EMI filter has been placed far from the transformer to avoid possible crosstalk of

EMI noise