APPENDIX A: CFL DEMONSTRATION BOARD

WITH THE L6569

A demonstration board was developed as an ex-

ample for Compact Fluorescent Lamp ballast. It is

optimised for a CF18DT/E/830 18W lamp from

Osram-Sylvania. Using the L6569 the circuit

achieves preheat, ignition and normal lamp op-

eration. The power transistors are two STD3NA50

500V-3

Ω MOSFETs in I-PACK package.

Board description

The three sections of the board are an AC input

rectifier, the half bridge inverter, and the resonant

ballast. By changing the connection on the input

mains, the ballast can operate either on 120 Vac

mains with a voltage doubler rectification, or on

230 Vac mains with a full wave rectification. The

charging the bulk capacitors. The L6569 operates

with a single 50 kHz switching frequency pro-

synchronize the oscillator to keep the switching in

ZVS mode. The control circuit requires 4.5 mA to

supply the I.C., the MOS gate drives, and the os-

cillator. Its supply delivers at least 6.5 mA as de-

scribed in appendix B. The start up resistor also

balances the voltage across the two bulk capaci-

tors.

Figure 23. CFL ballast diagram for a 18W

CFD18T/E lamp with 120/230 Vac inputs.

The resonant ballast

the lamp ignition voltage and the nominal lamp

current. During the ignition the lamp impedance is

essentially infinite, and the filaments resistance is

only the serial load. To generate the ignition volt-

age, the switching frequency is set close to the

resonance frequency. In normal operation the

choke resonates

(parallel loading), but also with the decoupling ca-

heat uses a 150

Ω Positive Temperature Coeffi-

cient thermistor. Inserted in the capacitive series

ment current during the initial 0.8 s (reference:

307C1253BHEAB from CERA-MITE).

Basic ballast electrical characteristics

Input voltage: 120 or 230 Vac by input connec-

tions change

Switching frequency: 50kHz

Average dc line voltage range: Vdc from 260 to 355

Nominal supply current: 0.17A rms @ 310 Vdc

Nominal output power: 17W

Minimum ignition voltage: 700V peak @ 260 Vdc

Nominal preheat current: 0.45 Arms during 0.8s

@ 310 Vdc

L1=2.4mH

L1=2.4mH core TH LCC E2006-B4 Ref also VOGH 575 0409200 2.4mH

C7-C8=PS8n2J H3 630-2A TH

D7

D4

D5

D6

R1 15 1W

C2

47

µF

250V

R8

120K

1/2W

R5 100K

C5

47

µF

250V

C3

4.7

µF

25V

D8

1N4148

D1

ZPD 18V

R4

27K

1/4W

C1

560pF

50V

220V

N

110V

R6 47 1/4W

R2 22 1/4W

1/4W

R3 22 1/4W

C4100nF 50V

D2

D3 BYW100-100

C9 470pF 630V

Q1

STD4NK50

Q2

STD4NK50

R7

180K

1/4W

C6

100nF

250V

C8

8.2nF

630V

(*)

C7

8.2nF

630V

(*)

CFL LAMP

SYLVANIA DELUX T/E 18W

R9

180K

1/4W

L6569

D96IN419C

RF

CF

GND

LVG

OUT

HVG

BOOT

4 x 1N4006

1/2W

BYW100-100

R10 10K

RV1

PTC 150

350V

(*)

Figure 23.

AN880 APPLICATION NOTE

11/14