© 2006 Fairchild Semiconductor Corporation

www.fairchildsemi.com

FSQ0170RNA, FSQ0270RNA Rev. 1.0.5

12

Typical Application Circuit

Features

 High efficiency (> 78% at 115 VAC and 230 VAC input)

 Low standby mode power consumption (< 0.8W at 230 VAC input and 0.5W load)

 Enhanced system reliability through various protection functions

 Internal soft-start (10ms)

 Line UVLO function can be achieved using external component

Key Design Notes

 The delay time for overload protection is designed to be about 30ms with C8 of 47nF. If faster/slower triggering of

OLP is required, C8 can be changed to a smaller/larger value (e.g. 100nF for about 60ms).

 ZP1, DL1, RL1, RL2, RL3, RL4, RL5, RL7, QL1, QL2, and CL9 build a Line Under-Voltage Lockout block (UVLO).

The Zener voltage of ZP1 determines the input voltage that makes FPS turn on. RL5 and DL1 provide a reference

voltage from VCC. If the input voltage divided by RL1, RL2, and RL4 is lower than the Zener voltage of DL1, QL1 and

QL2 turn on and pull down VFB to ground.

 An evaluation board and corresponding test report can be provided.

1. Schematic

Figure 21. Demo Circuit

Application

Output power

Input Voltage

Output Voltage (Max. Current)

PC Auxiliary Power Supply

(Using FSQ0270RNA)

15W

Universal input

(85-265 VAC)

5V (3A)

C9

1000

F

16V

C5

470

F

10V

R13

open

J1

FB

J4

0

QL2

KSP2222A

DL1

1N5233B

RL3

1k

RL5

30k

RL1 1M

RL2

1M

ZD1

1N4745

RL4

120k

DS1

1N4007

R10

2

R11

1.2k

1%

7

J2

0

ZR1

80

9,

RL7

40k

RS1

9

QL1

KSP2907A

R12

open

CS1

1.5nF

CL9

10

F

50V

J3

open

C8

47nF

C1

2.2nF

AC250V

R14

30

C2

22

F

400V

C3

22

F

400V

C4

1000

F

16V

1 2 3 4

8 7 6 5

U3

FSQ0270RNA

1

2

3

CON1

Input

D2

1N4007

D3

1N4007

D4

1N4007

D5

1N4007

R6

2.4 1W

L1

330

H

L3

0

R2

4.7k

R8

open

1

6,

3

10

4

5

T1

EE2229

D1

SB540

1

2

U1A

FOD817A

C10

1nF

250V

L2

1

H

2

3

1

U2

TL431A

R5

1.25k

1%

R4

100

R3

560

R9

10k

C6

47nF

1

2

CON2

Output

D6

1N4007

C7

47

F

25V

3

4

U1B

FOD817A

ZDS1

P6KE180A

ZP1

1N4762

ZD2

open

FSQ0x70RNA Rev. 1.12