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AN628 APPLICATION NOTE

DESIGN PROCEDURE.

In order to fix the described concepts, here follows a brief description of a possible design flowchart referred to

a typical "low-medium range power" PFC application.

Design target specification:

The design starts fixing the operating conditions.

– The switching frequency 100kHz ///

µF

– The maximum current ripple at nominal load has been chosen = 35%

The circuit in fig. 23 can be proposed as reference for medium range power PFC application.

C7

220nF

100V

R17

806K

1%

R17

806K

1%

R22

R23

R19

1.1M

5%

R19

1.1M

5%

R8

33K

5%

R7 360K 5% R6 620K 5%

R6

620K

5%

4

7

BRIDGE

4 x BY214

C1

220nF

400V

R21

5.1K

1%

L4981A

2

R15

10K

0.5W

R14

56

0.5W

C10

15nF

100V

19

15

D4

1N4150

DZ

22V

0.5W

C11

100

µF

25V

D3 1N4150

D3

2N2222

C8

220nF

100V

L 0.9mH

14

13

C9

330nF

R12

220K

5%

3

C12

270pF

630V

STH/STW15NB50

R13

Q1

Q2

STK2N50

D5

BYT

11600

R18

1.8K

4W

20

R11

560 1%

R3

2.7K

5%

R5

27K 5%

0.07 2W

C3

1nF

R4

2.7K

5%

R16

24K

1%

15 5%

C4

1nF

C6

1

µF

16V

61

R2

11K

1%

R10

21K

1%

R1

412K

1%

R9

910K

1%

R1

412K

1%

R9

910K

1%

D1 5TTA5060

12

C5

1

µF

16V

11

17

18

9

5

8

FUSE

C2

100

µF

450V

+

-

Vo

D93IN029C

Vi

88VAC to 254VAC

NTC

D2 1N4150

R20

10K 5%