ICB1FL02G Datasheet, PDF (6/37 Pages) Infineon Technologies AG – Smart Ballast Control IC for Fluorescent Lamp Ballasts

ICB1FL02G
Pin Configuration and Description
PFCGD (PFC gate drive, Pin 5)
The Gate of the MOSFET in the PFC preconverter
designed in boost topology is controlled by this pin.
There is an active L-level during UVLO and a limitation
of the max. H-level at 11V during normal operation.
Turning on the MOSFET softly (with a reduced di_DRAIN/
dt), the Gate drive voltage rises within 220ns from L-
level to H-level. The fall time of the Gate voltage is less
than 50ns in order to turn off quickly. A resistor of about
10Ohm 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 is
recommended.
The PFC section of the IC controls a boost converter as
a PFC preconverter in discontinuous conduction mode
(DCM). Typically the control starts with Gate drive
pulses with an on-time of 1µs increasing up to 24µs and
a off-time of 40µs. As soon as a sufficient ZCD (zero
current detector) signal is available, the operating
mode changes from a fixed frequent operation to an
operation with variable frequency. During rated and
medium load conditions we get an operation with
critical conduction mode (CritCM), that means
triangular shaped currents in the boost converter choke
without gaps when reaching the zero level and variable
operating frequency. During light load (detected by the
internal error amplifier) we get an operation with
discontinuous conduction mode (DCM), that means
triangular shaped currents in the boost converter choke
with gaps when reaching the zero level and variable
operating frequency in order to avoid steps in the
consumed line current.
PFCCS (PFC current sense, Pin 6)
The voltage drop across a shunt resistor located
between Source of the PFC MOSFET and GND is
sensed with this pin. If the level exceeds a threshold of
1V for longer than 260ns the PFC Gate drive is turned
off as long as the ZCD (zero current detector) enables
a new cycle. If there is no ZCD signal available within
40µs after turn-off of the PFC Gate drive, a new cycle
is initiated from an internal start-up timer.
PFCZCD (PFC zero current detection, Pin 7)
This pin senses the point of time when the current
through the boost inductor becomes zero during off-
time of the PFC MOSFET in order to initiate a new
cycle. The moment of interest appears when the
voltage of the separate ZCD winding changes from
positive to negative level which represents a voltage of
zero at the inductor windings and therefore the end of
current flow from lower input voltage level to higher
output voltage level. There is a threshold with
hysteresis, for increasing voltage a level of 1,5V, for
decreasing voltage a level of 0,5V, that detects the
change of inductor voltage. A resistor connected
between ZCD winding and sense input limits the sink
and source current of the sense pin, when the voltage
of the ZCD winding exceeds the internal clamping
levels (6,3V and -2,9V @ 4mA) of the IC.
If the sensed level of the ZCD winding is not sufficient
(e.g. during start-up), an internal start-up timer will
initiate a new cycle every 40µs after turn-off of the PFC
Gate drive.
PFCVS (PFC voltage sense, Pin 8)
The intermediate circuit voltage (bus voltage) at the
smoothing capacitor is sensed by a resistive divider at
this pin. The internal reference voltage for rated bus
voltage is 2,5V. There are further thresholds at 0,375V
(15% of rated bus voltage), 1,83V (73% of rated bus
voltage) and 2,725V (109% of rated bus voltage) for
detecting open control loop, undervoltage and
overvoltage.
RFRUN (Set R for run frequency, Pin 9)
A resistor from this pin to ground sets the operating
frequency of the inverter during run mode. Typical run
frequency range is 20kHz to 100kHz. The set resistor
R_RFRUN can be calculated based on the run frequency
f_RUN according to the equation
RRFRUN
=
5-----⋅_{---1---0---8----}Ω_{-----H-----z-}
fRUN
RFPH (Set R for preheating frequency, Pin 10)
A resistor from this pin to ground sets together with the
resistor at pin 9 the operating frequency of the inverter
during preheat mode. Typical preheat frequency range
is run frequency (as a minimum) to 150kHz. The set
resistor R_RFPH can be calculated based on the preheat
frequency f_PH and the resistor R_RFRUN according to the
equation:
RRFPH = -f-----P-------H-----------_â‹-R-----R----R------R--F------F--R------R---U-----U----N------N---------–-----1-
5 ⋅ 108ΩHz
The total value of both resistors R_RFPH and R_RFRUN
switched in parallel should not be less than 3,3kOhm.
RTPH (Set R for preheating time, Pin 11)
A resistor from this pin to ground sets the preheating
time of the inverter during preheat mode. A set resistor
range from zero to 18kOhm corresponds to a range of
preheating time from zero to 2000ms subdivided in 127
steps.
RES (Restart after lamp removal, Pin 12)
A source current out of this pin via resistor and filament
to ground monitors the existence of the low-side
filament of the fluorescent lamp for restart after lamp
Datasheet Version 1.2
6
February 2006