ICB1FL02G Datasheet, PDF (9/37 Pages) Infineon Technologies AG – Smart Ballast Control IC for Fluorescent Lamp Ballasts

ICB1FL02G
Functional Description
3 Functional Description
3.1 Typical operating levels during start-up
The control of the ballast should be able to start the operation within less than 100ms. Therefore the current
consumption of the IC is less than 150µA during UVLO. With a small start-up capacitor (about 1µF) and a power
supply, that feeds within 100µs (charge pump of the inverter) the IC can cover this feature.
As long as the Vcc is less than 10,5V, the current consumption is typically 80µA. Above a Vcc voltage level of
10,5V the IC checks whether the lamp(s) are assembled by detecting a current across the filaments. The low-side
filament is checked from a source current (20µA typ.) out of pin RES, that produces a voltage drop at the sense
resistor, which is connected via low-side filament to ground. An open filament is detected, when the voltage level
at pin RES is above 1,6V. The high-side filament (or the high-side of a series topology) is checked by a current
(15µA typ.) into the LVS pin. An open high-side filament causes a higher source current (41µA / 34µA typ.) out of
pin RES in order to exceed the 1,6V threshold. If one of both filaments is not able to conduct the test current, the
control circuit is disabled. The IC is enabled as soon as a sufficient current is detected across the filaments or the
supply voltage drops below the UVLO threshold (10,5V) e.g. by turn-off and turn-on of mains switch.
V_CC
14,0V
10,5V
I_VCC
80µA
V_RES
3,2V
1,6V
UVLO
START-UP
HYSTERESIS
80µA
<150µA
I_RES
20µA
I_LVS
>15µA
20µA
>15µA
IC ACTIVE
SOFTSTART
t
5mA
+ QGate
t
<3,2V
t
t
< +/- 2,5mA ^t
Figure 2 Progress of levels during a typical start-up.
When the previous conditions are fulfilled, and Vcc has reached the start-up threshold (14V), there is finally a
check of the Bus voltage. If the level is less than 15% of rated Bus voltage, the IC is waiting in power down mode
until the voltage increases. If the level is above 109% of rated Bus voltage there is no Gate drive, but an active
IC. The supply voltage Vcc will fall below the UVLO threshold and a new start-up attempt is initiated.
As soon as start-up conditions are fulfilled the IC starts driving the inverter with the start-up frequency of 125kHz.
Now the complete control including timers and the PFC control can be set in action. There are current limitation
thresholds for PFC preconverter and ballast inverter equipped with spike filters. The PFC current limitation
interrupts the on-time of the PFC MOSFET if the voltage drop at shunt resistor exceeds 1V and restarts after next
input from ZCD. The inverter current limitation operates with a first threshold of 0,8V which increases the operating
frequency during ignition mode if exceeded. A second threshold is provided at 1,6V that stops the whole control
circuit and latches this event as a fault.
Datasheet Version 1.2
9
February 2006