ICB1FL02G Datasheet, PDF (15/37 Pages) Infineon Technologies AG – Smart Ballast Control IC for Fluorescent Lamp Ballasts

ICB1FL02G
Functional Description
2,5
2,4
2,3
2,2
2,1
2
1,9
1,8
1,7
1,6
1,5
1,4
1,3
1,2
1,1
1
0
50
100
150
200
250
I _LVS = Lamp Voltage / Sense Resistor [uA] of smaller Amplitude
Figure 13 Maximum ratio of amplitudes versus sense current.
Furthermore the rectification effect (EOL2) is detected when the ratio of the higher amplitude divided by the
smaller amplitude of the lamp voltage is bigger than illustrated in Fig. 13. for longer than 500ms. The ratio is
evaluated each cycle of the lamp voltage. The limit of the ratio increases dependend on the peak current of the
smaller amplitude of the lamp voltage from 1,15 at I_LVS= 200µA nonlinear to 1,4 at I_LVS= 50µA.
If the EOL2 conditions are detected, the control is disabled and the status is latched as a failure mode. Measuring
the duration of incorrect operating conditions is done by a check every 4ms. If the fault condition is existing, a
counter counts up, if the fault condition is not existing, the counter counts down. So we get an integration of the
fault events that allows a very effective monitoring of strange operating conditions.
The detection of EOL1 and EOL2 requires an AC current input at the sense pins LVS1 and LVS2 for proper
operation. A DC current at pin LVS will lead to a defined reaction only, if the level exeeds 175µA (typically) for
longer than 610µs which results in a shut down and change over into the latched failure mode.
3.5 Detection of capacitive mode operating conditions
If there happens a situation like an open resonant circuit (e.g. a sudden break of the tube) the voltage across the
resonant capacitor and current through the shunt of the low-side inverter MOSFET rise quickly. This event is
detected by inverter current limitation (1,6V) and results in shut down of the control. This status is latched as a
failure mode.
In another kind of failure the operation of the inverter may leave the zero voltage switching (ZVS) and move into
capacitive mode operation or into operation below resonance. There are two different levels for capacitive mode
detection implemented in the IC. A first criteria detects low deviations from ZVS (CapLoad1) and changes
operation into fault mode, if this operation lasts longer than 500ms. For CapLoad1 the same counter is used as
for the end-of-life evaluation.
Datasheet Version 1.2
15
February 2006