EVAL6569 STMicroelectronics, EVAL6569 Datasheet - Page 13

• Manufacturer Part Number: EVAL6569
• Description: BOARD EVAL LIGHTING L6569
• Manufacturer: STMicroelectronics
• Type: Charge Pumpsr

Specifications of EVAL6569

• Mfg Application Notes: L6569, AN880 App Note
• Main Purpose: Lighting, Ballast Control
• Embedded: No
• Utilized Ic / Part: L6569
• Primary Attributes: 18 W, Optimized for a CF18DT/E/830, 120 or 230 VAC
• Secondary Attributes: Preheating Done with a PTC
• Input Voltage: 230 V
• Product: Power Management Modules
• Supply Current: 0.17 A
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: L6569
• Other names: 497-4738

APPENDIX B: Rating of the capacitive supply
with the L6569 driver
The supply is made with the snubber and a start
up resistor R
A snubber circuit is used to minimize the MOS-
FETs dissipation. It also achieves a non dissipa-
tive supply as shown on figure 10.
The MOSFETs gate charge, the driver consump-
tion, the oscillator, and the shunt regulator, define
the circuit consumption.
current is I
Where Q
When V
driver is only consuming. Its current must be mini-
mal to reduce the dissipation of the resistor R
The L6569 has a 150 A start up current, and the
maximum resistance is 2M for a 230Vac line ap-
plication.
We can also reduce the resistor value to get a
faster start up time T
Where C
line voltage.
When the timer oscillates, the capacitor C sup-
S
I
V
R
I
= 2 Q
QS
REG
I
SAV
G
S
F
is lower than the UVLO threshold U
S
S AV
supply voltage
the supply voltage
the MOSFET gate charge
the oscillator resistor and V
the driver supply current
is the supply capacitor, and V
the shunt regulator current.
S
> 2 I
.
:
G
T
S
fsw + I
G
R
+ I
S
S
.
QS
QS
C
V
S
+ I
DC
We can estimate this
+
OSC
U
R
UVLO
V
F
S
+ I
2
REG
+ I
S
REG
the driver
=
UVLO
DC
, the
the
S
.
plies the lamp current during the lower MOS turn
off. To avoid any cross conduction its capacitance
is limited by the driver dead time T
26). Hence the capacitive supply current I
limited.
Where I
switching frequency.
For a ballast such as a CFL one this circuit sup-
plies easily the required current. For instance with
a CF18DT lamp ( I
1nF on 120Vac line, 470 pF on 230 Vac line. At
50 kHz the average capacitive current is 6 mA in
both cases.
Figure 26: Cross conduction of the snubber
GND
GND
GND
I
L
CAV
200 ns/dv ; 50 V/dv ; 0.1 A/dv
is the peak lamp current, and F
capacitor with the upper MOSFET:
capacitor current and voltage
waveforms.
= C V
AN880 APPLICATION NOTE
T
D
DC
C
L
> 230 mA) the capacitor is
F
T
V
SW
D
DC
< I
I
L
L
T
D
D
V
I
RF
C
F
(see figure
HVG
SW
C
+ V
SW
is also
13/14
OUT
the