ICB2FL03G Datasheet, PDF (10/60 Pages) Infineon Technologies AG – 2nd Generation FL Controller for Fluorescent Lamp Ballasts

1.3
Pin Functionality
ICB2FL03G
Controller for Fluorescent Lamp Ballasts
Pin Configuration and Functionality
LSGD (low-side gate drive, pin 1)
The gate of the low-side MOSFET in a half-bridge inverter topology is controlled by this pin. There is an active
L-level during UVLO (under voltage lockout) and limitation of the max H-level at 11.0 V during normal operation.
In order to turn on the MOSFET softly (with a reduced di_DRAIN/dt); the gate voltage typically rises within 245 ns from
L-level to H-level. The fall time of the gate voltage is less than 50 ns in order to turn off quickly. This measure
produces different switching speeds during turn-on and turn-off as it is usually achieved with a diode parallel to a
resistor in the gate drive loop. It is recommended to use a resistor of typically 10 Ω between drive pin and gate in
order to avoid oscillations and in order to shift the power dissipation of discharging the gate capacitance into this
resistor. The dead time between the LSGD signal and HSGD signal is self-adapting between 1.05 μs and 2.1 μs.
LSCS (low-side current sense, pin 2)
This pin is directly connected to the shunt resistor which is located between the source terminal of the low-side
MOSFET of the inverter and ground.
Internal clamping structures and filtering measures allow for sensing the source current of the low-side inverter
MOSFET without additional filter components.
The first threshold is 0.8 V. If this threshold is exceeded for longer than 500 ns during preheat or run mode, an
inverter overcurrent is detected and causes a latched shutdown of the IC. The ignition control is activated if the
sensed slope at the LSCS pin reaches typically 205 mV/μs ± 25 mV/μs and exceeds the 0.8 V threshold. This
stops the frequency decrease and waits for ignition. The ignition control is now continuously monitored by the
LSCS PIN. The ignition control is designed to handle choke operation in saturation during ignition in order to
reduce the choke size.
If the sensed current signal exceeds a second threshold of 1.6 V for longer than 500 ns during start-up, soft start,
ignition mode and pre-run, the IC changes over into latched shutdown.
There are further thresholds active at this pin during run mode that detect capacitive mode operation. An initial
threshold at 50 mV needs to sense a positive current during the second 50 % on-time of the low-side MOSFET for
proper operation (cap. load 1). A second threshold of -50mV senses the current before the high-side MOSFET is
turned on. A voltage level below this threshold indicates faulty operation (cap. load 2). Finally a third threshold at
2.0 V senses even short overcurrent during turn-on of the high-side MOSFET, typical for reverse recovery currents
of a diode (cap. load 2). If any of these three comparator thresholds indicates incorrect operating conditions for
longer than 620 μs (cap. load 2) or 2500 ms (cap. load 1) in run mode, the IC turns off the gates and changes into
fault mode due to detected capacitive mode operation (non-zero voltage switching).
The threshold of -50 mV is also used to adjust the dead time between turn-off and turn-on of the half-bridge drivers
in a range of 1.05 μs to 2.1 μs during all operating modes.
Vcc (supply voltage, pin 3)
This pin provides the power supply of the ground related section of the IC. There is a turn-on threshold at 14.0 V
and an UVLO threshold at 10.6 V. The upper supply voltage level is 17.5 V. There is an internal zener diode
clamping V_CC at 16.3 V (at I_VCC = 2 mA typically). The maximum zener current is internally limited to 5 mA. An
external zener diode is required for higher current levels. Current consumption during UVLO and during fault mode
is less than 170 μA. A ceramic capacitor close to the supply and GND pin is required in order to act as a low-
impedance power source for gate drive and logic signal currents. In order to skip preheating after short
interruptions to the mains supply it is necessary to feed the start-up current (160 μA) from the bus voltage. Note:
for external V_CC supply, see notes in the flowchart (Section 3.3).
Final Data Sheet
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V1.1, 2013-08-14