October 2007

Rev 1

1/25

AN2623

Application note

Evaluation board

for off-line forward converter based on L5991

Introduction

This application note gives a practical example of a 160 W, isolated, forward converter using

the L5991, high frequency current mode PWM controller. Design procedures for both the

power stage and controller are presented.

Generally for this power level the norm ICE61000-3-2 imposes the use of a PFC pre-

regulator stage, but some countries do not require compliance to this norm. The forward

converter presented here does not have a PFC.

Figure 1.

160 W off-line forward converter, evaluation board

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