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Power Factor Correction

The power factor correction section consists of the L6561D Power Factor Controller IC (IC1), MOSFET

M1, inductor L2, diode D2, capacitor C8 and additional biasing, sensing and compensation compo-

nents (see schematic diagram). This is a boost topology designed to step-up and regulate the output

DC bus voltage while drawing sinusoidal current from the line (low THD) which is “in phase” with the

AC input line voltage (HPF). The design of the power factor correction section was taken from the

L6561D data sheet and information on the operation and design considerations for the L6561D are

contained therein.

Ballast Control

The ballast control section is built around the IR21592 Ballast Control IC, IC2 of the Demo board.

The IR21592 contains an oscillator, a high voltage half-bridge gate driver, an analog dimming inter-

face and lamp fault protection circuitry. A block diagram of the IR21592 IC is shown in figure 1 and a

state diagram of the IR21592 is shown in figure 2.

Figure 1: IR21592 Block Diagram

LEVEL

SHIFT

PULSE

FILTER &

LATCH

3

5.1V

4

6

10V

2

1.3uA

5

7

8

5.1V

1.0V

CPH

DIM

MAX

MIN

FMIN

IPH

VCO

Q

S

R2 Q

R1

Q

T

RQ

16

14

15

VS

HO

VB

13

11

12

COM

LO

VCC

15.6V

10

1.6V

CS

UNDER-

VOLTAGE

DETECT

1

VDC

I

CT

I

CT

15uA

1uA

60uA

CT

I

FMIN

Q

S

RQ

Q

S

RQ

I

DIM

5.1V

1

0

VCC

400ns

DELAY

5.1V

3V

R

FB

V

ERR

REF

FB

CT

OVER-

TEMP

DETECT

IGN

DET

Q

S

R

Q

9

SD

2.0V

7.6V

Q

S

RQ

I

DT

I

CT

+

I

4/R

FMIN

1/R

FMIN

0.1/R

FMIN

0.1/R

FMIN