ICB2FL02G Datasheet, PDF (20/55 Pages) Infineon Technologies AG – Smart Ballast Control IC for Fluorescent Lamp Ballasts

2^nd Generation FL-Controller for FL-Ballasts
Functional Description
2.4 PFC Pre Converter
2.4.1 Discontinuous Conduction and Critical Conduction Mode Operation
The digital controlled PFC pre converter starts with an internally fixed ON time of typical t_ON = 4.0µs
and variable frequency. The ON – time is enlarged every 280 µs (typical) up to a maximum ON – time
of 22.7 µs. The control switches quite immediately from the discontinuous conduction mode (DCM)
over into critical conduction mode (CritCM) as soon as a sufficient ZCD signal is available. The
frequency range in CritCM is 22 kHz until 500 kHz, depending on the power (Figure 14) with a
variation of the ON time from 22.7 µs > t_ON > 0.5µs.
Discontinuous Conduction Mode (DCM) <> Critical Condution Mode (CritCM)
1000,00
100,00
100,00
10,00
10,00
1,00
1,00
0,10
0,01
0,01
0,10
1,00
Normalized Output Power [% ]
Frequency DCM Frequency CritCM Ton DCM
10,00
Ton CritCM
0,10
100,00
Figure 14 Operating Frequency and ON Time versus Power in DCM and CritCM Operation
For lower loads (P_OUTNorm < 8 % from the normalized load²) the control operates in discontinuous
conduction mode (DCM) with an ON – time from 4.0µs and increasing OFF – time. The frequency
during DCM is variable in a range from 144 kHz down to typically 22 kHz @ 0.1 % Load (Figure 14).
With this control method, the PFC converter enables a stable operation from 100 % load down to 0.1
%. Figure 14 shows the ON time range in DCM and CritCM (Critical Conduction Mode) operation. In
the overlapping area of CritCM and DCM is a hysteresis of the ON time which causes a negligible
frequency change.
2 _{Normalized Power @ Low Line Input Voltage and maximum Load}
Preliminary Datasheet
Page 20 of 55
ICB2FL02G
V1.2