UNITRODE INTEGRATED CIRCUITS

7 CONTINENTAL BLVD.

• MERRIMACK, NH 03054

TEL. (603) 424-2410

• FAX (603) 424-3460

APPLICATION INFORMATION: A 100 Watt Power Factor Preregulator

This circuit demonstrates a complete power factor preregulator based on the UC3852. This preregulatorwill supply

up to 100 watts at 400VDC and exhibit power factor greater than 0.995 with less than 10% total harmonic distortion.

Operating input range is 90V to 160V RMS at 50Hz to 60Hz.

This design is intentionally simple, yet fully functional. The UC3852 can also be used in designs featuring soft start,

over-voltage protection, wide power-line voltage operation, and fault latching. For more information on applying

the UC3852, refer to Unitrode Application Note U–132.

PARTS LIST

UC1852

UC2852

UC3852

UDG-92004

C1

0.47

µF/250VAC X2 Class Polyester

C2

1nF/16V Ceramic

C3

68

µF/35V Aluminum Electrolytic

C4

180pF/16V Ceramic

C5

0.1

µF/16V Polyester or Ceramic

C6

82

µF/450V Aluminum Electrolytic

D1

2A/500V Bridge Rectifier (Collmer

KBPC106 or Powertex MB11A02V60)

D2

100mA/50V Switching Diode (1N4148)

D3

2A/500V 250ns Recovery-Time Rectifier

(Motorola MR856)

IC1

UC3852N Power Factor Controller IC

Q1

IRF830 4.5A/500V 1.5

Ω Power FET

L1

680

µH (Renco RL3792 with

10 Turn 24 AWG Secondary)

R1

150k

R2

0.2

R3

10

R4

13.3k

R5

1M

R6

20k

R7

200k

R8

200k

5