UCC2817A, UCC2818A

UCC3817A, UCC3818A

SLUS577C − SEPTEMBER, 2003 − REVISED MARCH 2009

BiCMOS POWER FACTOR PREREGULATOR

1

www.ti.com

FEATURES

Power Factor

DESCRIPTION

The UCC3817A and the UCC3818A family

provides all the functions necessary for active

power

factor

corrected

preregulators.

The

controller achieves near unity power factor by

shaping the ac input line current waveform to

correspond to that of the ac input line voltage.

Average current mode control maintains stable,

low distortion sinusoidal line current.

Designed in Texas Instrument’s BiCMOS process,

the UCC3817A/UCC3818A offers new features

such as lower start-up current, lower power

dissipation, overvoltage protection, a shunt UVLO

detect

circuitry,

a

leading-edge

modulation

technique to reduce ripple current in the bulk

capacitor and an improved, low-offset (

±2 mV)

current amplifier to reduce distortion at light load

conditions.

BLOCK DIAGRAM

UDG-03122

VREF

9

2

16

1

15

10

5

4

DRVOUT

GND

CAI

VCC

OVP/EN

VAOUT

1.9 V

PKLMT

7.5 V

REFERENCE

UVLO

16 V/10 V (UCC3817A)

10.5 V/10 V (UCC3818A)

VCC

3

OSCILLATOR

12

RT

14

CT

SQ

R

PWM

LATCH

+

−

PWM

CAOUT

+

−

+

−

+

−

SS

VOLTAGE

ERROR AMP

8.0 V

13

7

11

VSENSE

VFF

8

IAC

6

MOUT

MIRROR

2:1

X2

+

−

7.5 V

ENABLE

OVP

÷

X

X

MULT

OSC

CLK

CLK

CURRENT

AMP

16 V (FOR UCC3817A ONLY)

+

−

0.33 V

ZERO POWER

R

+

−

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of Texas Instruments

standard warranty. Production processing does not necessarily include

testing of all parameters.

Copyright

 2006 − 2009, Texas Instruments Incorporated

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.