EVAL6569 Datasheet, PDF (11/14 Pages) Panasonic Semiconductor – THE L6569 A NEW HIGH VOLTAGE IC DRIVER FOR ELECTRONIC LAMP BALLAST

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-3Ω 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
input resistor R1 limits the initial inrush current
charging the bulk capacitors. The L6569 operates
with a single 50 kHz switching frequency pro-
grammed by R4 and C1. Two fast diodes D2 & D3
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.
Figure 23.
AN880 APPLICATION NOTE
The resonant ballast
The value of the choke (L1) and the two capaci-
tors (C7 & C8) in parallel with the lamp determine
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 with the capacitors C7 & C8
(parallel loading), but also with the decoupling ca-
pacitor C6 (serial loading). The current mode pre-
heat uses a 150Ω Positive Temperature Coeffi-
cient thermistor. Inserted in the capacitive series
(C7 & C8), the PTC produces a 0.45 Arms fila-
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
R8
120K
1/2W
4 x 1N4006
D7 D4
220V
D6 D5
N
R1 15 1W
110V
C5
47µF
250V
C2
47µF
250V
R5 100K
1/2W
C3
4.7µF
25V
C4100nF 50V
V_S
BOOT
RF
R4
27K
1/4W
CF
D8
1N4148
C1
560pF
50V
L6569
HVG
R2 22 1/4W
OUT
R10 10K
1/4W
LVG R3 22 1/4W
GND
C9 470pF 630V
R6 47 1/4W
(*)
D1
ZPD 18V
L1=2.4mH core TH LCC E2006-B4 Ref also VOGH 575 0409200 2.4mH
C7-C8=PS8n2J H3 630-2A TH
D96IN419C
Q1
STD4NK50
R9
180K
1/4W
L1=2.4mH
Q2
STD4NK50
R7
180K
1/4W
BYW100-100
C6
100nF
250V
C7
8.2nF
630V
(*)
C8
8.2nF
630V
(*)
D2
D3 BYW100-100
CFL LAMP
SYLVANIA DELUX T/E 18W
(*) Polypropylene, Capacitors 630V rated V_L
RV1
PTC 150
350V
11/14