ICB1FL03G Datasheet, PDF (32/38 Pages) Infineon Technologies AG – Smart Ballast Control IC for Fluorescent Lamp Ballasts

ICB1FL03G
Application Examples
Finally the resistors R24, R25 can be calculated from IC20 and the current limitation threshold during ignition
mode.
--^R----²---⁴----^â‹---^R----²---⁵---
R24 + R25
=
-^V----^L----^S----^C----^S----^L----^I---^M------^I--^T--
IC ₂₀
=
--⁰---^,---⁸---^V-----
1, 65A
=
0, 485Ω
Selected values are R24= 0,82Ohm; R25= 0,82Ohm.
Lamp voltage sense resistors R41, R42, R43:
The selected lamp type 54W-T5 has a typical run voltage of 167V peak. We decide to set the EOL-thresholds at
a level of 1,5 times the run voltage level (= 250,5V peak).
R41 + R42 + R43
=
----^V----^L----^E----^O-----^L-----
ILVSEOL
=
2_---5_----0_--,_---5_----V_---
215 µ A
=
1165 k Ω
Selected values: R41= 390k; R42= 390k; R43= 390k (R41+R42+R43=1170k).
Current source resistors R34, R35 for detection of high-side filament:
R34 + R35
=
-----------^V-----^I--^N-----^M------^I--^N--------------
ILVSSINKMAX
–
(
R41
+
R42
+
R43
)
=
-²---⁰---⁰---^V---- – (1170k)
26 µ A
=
6522 k Ω
Selected values: R34= 2,2M; R35= 2,2M;
Current limitation resistor R30 for floating bootstrap capacitor C14:
A factor of 2 is provided in order to keep current level significant below LSCS turn-off threshold.
R30
≥
---²----^â‹---^V-----^C----^C-----^O----^N-----
VLSCSOVC
⋅
-^R-----²---⁴----^â‹---^R----²---⁵---
R24 + R25
=
2_-----⋅_---1_---4_---V_---
1, 6V
⋅
-⁰---^,---⁸---²-----^â‹---⁰---^,---⁸---²--
0, 82 + 0, 82
=
7, 18Ω
Selected value: R30= 10Ohm.
Low-side filament sense resistor R36:
For a single lamp ballast
Selected value: R36= 56k
R36
≤
-^V----^R----^E-----^S---^C-----¹---^M------^I---^N--
IRES3MIN
=
--¹---^,---⁵---⁵----^V-----
27, 0µA
=
57, 4kΩ
Low pass filter capacitor C19:
Capacitor C19 provides a low pass filter together with resistor R36 in order to suppress AC voltage drop at the
low-side filament. When we estimate an AC voltage of 10V peak-to-peak at low-side filament during run mode at
f_RUN= 40kHz, we need a suppression of at least a factor F_LP= 100 (-40dB).
C19
=
---------^F--^L2---^P---^–--¹-------
2 ⋅ π ⋅ fRUN ⋅ R36
=
---------¹--⁰--⁰--²--^–---¹------
2 ⋅ π ⋅ 40kHz ⋅ 56k
=
7, 1nF
Selected value for better ripple suppression: C19= 22nF.
Preliminary Datasheet Version 1.02
32
March 2009