Existing solutions

AN3276

6/22

Doc ID 17975 Rev 1

1.4

Passive recovery circuit

In the passive recovery circuit family the electrical schematic shown in Figure 5 is a good

example [see Section 5: References, 4.]; only two extra diodes and one resonant capacitor

are required.

Figure 5.

Passive recovery circuit

This circuit works well under unchanging external conditions. However, it is difficult to design

this kind of system in PFC applications since the current reset in the small inductor depends

on both boost diode recovery current and the external electrical conditions.

Although, the non-dissipative passive circuit requires fewer components, it is unfortunately

technically impractical in PFC applications. These examples highlight that the current

snubber method is well known but the technical challenge is to recover the L energy through

the application without affecting the five criteria listed in Section 1.2.

V mains

VOUT

D2

D 1

D

B

L

L B

T R

CR