ICB2FL03G Datasheet, PDF (26/60 Pages) Infineon Technologies AG – 2nd Generation FL Controller for Fluorescent Lamp Ballasts

ZCD @ AC Input Voltage
ICB2FL03G
Controller for Fluorescent Lamp Ballasts
Functional Description
ZCD @ DC Input Voltage
Rectified
AC Input Voltage
A
B
A
0
DC Input Voltage
Voltage at ₀
ZCD-Winding
PFC Gate
Drive Voltage ₀
PFC gate signal (gray) controlled by the V_PFCVS
PFC gate signal (blue) controlled by the ZCD
Figure 17 THD Optimization using adjustable Pulse Width Extension
In the case of DC input voltage (see DC input voltage in Figure 17), the pulse width gate signal is fixed as a
combination of the gate signal controlled by the V_PFCVS pin (gray) and the additional pulse width signal controlled
by the ZCD pin (blue) shown in Figure 17 ZCD @ DC input voltage.
The PFC current limitation at pin PFCCS interrupts the ON time of the PFC MOSFET if the voltage drop at the
shunt resistors R18 (Figure 3) exceeds V_PFCCS = 1.0 V (Figure 16). This interrupt will restart after the next
sufficient signal from ZCD becomes available (Auto Restart). The first value of the resistor can be calculated by
the ratio of the PFC mains choke and ZCD winding by the bus voltage and a current of typically 1.5 mA (see
equation below for a good practical value of resistance of ZCD). An adjustment of the ZCD resistor causes an
optimized THD.
R_ZCD
=
N _ZCD
N _PFC
*V_BUS
1.5mA
2.5
Detection of End-of-Life and Rectifier Effect
Two effects are present by End of Life (EOL): lamp overvoltage (EOL1) and a rectifier effect (EOL2).
After ignition (see 1 in Figure 18), the lamp voltage breaks down to its run voltage level with decreasing frequency.
On reaching the run frequency, the IC enters the pre-run mode for 625 ms. During this period, the EOL detection
is still disabled. In the subsequent run mode (2 in Figure 18) the detection of EOL1 (lamp overvoltage; see 3,
Figure 18) and EOL2 (rectifier effect; see 4, Figure 18) is enabled completely.
Final Data Sheet
26
V1.1, 2013-08-14