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AN1606 APPLICATION NOTE

To fit this, it has been choosen

For the capacitors, we set 80 dB of attenuation on the fundamental frequency using the commercial values: -

The design places two poles at 3Hz and 14Hz and 80 dB of attenuation at 100Hz.

Practical examples.

The preceeding points of this note have described the topology peculiarity. Remainder of the topics, for PFC

design, are similar to standard P.F.C. boost applications based on L4981A/B (see the related references and

application notes).

Starting from now, we can refer to real design examples.

In fact, in order to verify the efficacy of the described configuration, it have been checked a pair of application's

size. For evaluation porpoise, it has been realized a printed circuit.

Let us beginnes with and 800W P.F.C application.

800W Target:

1 - Wide range input voltage variation 110Vrms to 220Vrms.

2 - Output power 800W.

2 - Output voltage 400Vdc.

A switching frequency of 50 kHz has been chosen as a good compromise between the coil-size and the pow-

erMOS switching losses.

Boost Inductor design.

To design the boost inductor, the parameters under consideration are the percentage current ripple (as low as

possible) and the cost of the bobbin. This portion of the design is the same as for the standard topology.

In this application, in place of a single inductor connected to one of the phases, it has been chosen to split the

inductor into two sections (two windings on the same core) as shown in the connection diagram at fig.9.

R a

998k

Ω

2499

⋅

()

≡

=

R b

150k

Ω

=

Rc

30k

Ω

=











Ca

390nF

=

Cb

470nF

=



