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AN628 APPLICATION NOTE

The results, concerning the described circuit, have been tested. And the result are shortly here reported:

DEMO-BOARD:

Design process and Evaluation results

In order to provide a powerful tool for the complete evaluation of the L4981, It is available a populated Demo-

Board. The design process and the description for the demo, is here described.

The demo has been designed to operate in wide range mains and the size and is finalized for a "medium-high"

output power range.

Let us start fixing the overall target of the application.

Electrical target specification:

– Target efficiency

≥ 90% in nominal load conditions.

Chosen operation conditions of the application

– The rectified mains (100/120Hz) full load voltage ripple is ± 7-8 V (peak to peak) this is achieved using

– The maximum current ripple, in nominal load condition, is selected to be about 20%. This can be ob-

tained using the boost inductor L = 0.55mH and setting the switching frequency at 100kHz. ##

The demo is capable to deliver around 400W output power; anyway in order to limit the temperature, the rated

power is limited to 360W.

The schematic is shown in fig 24.

f

PF

A-THD

H3

H5H7H9

η

(Hz)

(W)

(%)

(%)

(%)

(%)

(%)

(V)

(V)

(W)

(%)

110

60

220

0.999

1.79

1.40

0.40

0.31

0.28

392

8

201

91.6

220

50

217

0.997

2.25

1.68

0.83

0.57

0.48

398

8

204

94.2