ICB1FL01G Datasheet, PDF (7/38 Pages) Infineon Technologies AG – Smart Ballast Control IC for Fluorescent Lamp Ballasts

ICB1FL01G
Pin Configuration and Description
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
removal. A capacitor from this pin directly to ground
eliminates a superimposed AC voltage that is
generated as a voltage drop across the low-side
filament. With a second sense resistor the filament of a
paralleled lamp can be included into the lamp removal
sense.
During typical start-up with connected filaments of the
lamp a current source I_RES3 (20µA) is active as long as
Vcc> 10,5V and V_RES< V_RESC1 (1,6V). An open Low-
side filament is detected, when V_RES> V_RESC1. Such a
condition will prevent the start-up of the IC. In addition
the comparator threshold is set to V_RESC2 (1,3V) and
the current source changes to I_RES4 (17µA). Now the
system is waiting for a voltage level lower than V_RESC2
at the RES-Pin that indicates a connected low-side
filament, which will enable the start-up of the IC.
An open high-side filament is detected when there is no
sink current I_LVSsink (12µA) into both of the LVS-Pins
before the V_CC start-up threshold is reached. Under
these conditions the current source at the RES-Pin is
I_RES1 (41µA) as long as Vcc> 10,5V and V_RES< V_RESC1
(1,6V) and the current source is I_RES2 (34µA) when the
threshold has changed to V_RESC2 (1,3V). In this way the
detection of the high-side filament is mirrored to the
levels on the RES-Pin.
Finally there is a delay function implemented at the
RES-Pin. When a fault condition happens e.g. by an
end-of-life criteria the inverter is turned-off. In some
topologies a transient AC lamp voltage may occur
immediately after shut down of the Gate drives which
could be interpreted as a lamp removal. In order to
generate a delay for the detection of a lamp removal
the capacitor at the RES-Pin is charged by the I_RES3
(20µA) current source up to the threshold V_RESC1 (1,6V)
and discharged by an internal resistor R_RESdisch , which
operates in parallel to the external sense resistor at this
pin, to the threshold V_RESC3 (0,375V). The total delay
amounts to 32 of these cycles, which corresponds to a
delay time between 30ms to 100ms dependent on
capacitor value.
In addition this pin is applied to sense capacitive mode
operation by use of a further capacitor connected from
this pin to the nod of the high-side MOSFET’s Source
terminal and the low-side MOSFET’s Drain terminal.
The sense capacitor and the filter capacitor are acting
as a capacitive voltage divider that allows for detecting
voltage slopes versus timing sequence and therefore
indicating capacitive mode operation. A typical ratio of
the capacitive divider is 410V/2,2V which results in the
capacitor values e.g. of 10nF and 53pF (56pF).
LVS1 (Lamp voltage sense 1, Pin 13)
Before the IC enters the softstart mode this pin has to
sense a sink current above 22µA which is fed via
resistors from the bus voltage across the high-side
filament of the fluorescent lamp in order to monitor the
existence of the filament for restart after lamp removal.
Together with LVS2 (pin 14) and RES (pin 12) the IC
can monitor the lamp removal of totally 4 lamps.
During run mode the lamp voltage is sensed by the AC
current fed into this pin via resistors. Exceeding one of
the two thresholds of either +230µA or -230µA cycle by
cycle for longer than 500ms, the interpretation of this
event is a failure due to EOL (end-of-life). A rectifier
effect is assumed if the ratio of the sequence of positive
and negative amplitudes is above 1,15 or below 0,85
for longer than 500ms. A failure due to EOL or rectifier
effect changes the operating mode from run mode into
a latched fault mode that stops the operation until a
reset occurs by lamp removal or by cycle of power.
If the functionality of this pin is not required (e.g. for
single lamp designs) it can be disabled by connecting
this pin to ground.
LVS2 (Lamp voltage sense 2, Pin 14)
Same functionality as LVS1 (pin 13) for monitoring a
paralleled lamp circuit.
HSGND (High side ground, Pin 17)
This pin is connected to the Source terminal of the
high-side MOSFET, which is also the nod of high-side
and low-side MOSFET. This pin represents the floating
ground level of the high-side driver and high-side
supply.
HSVCC (High side supply voltage, Pin 18)
This pin provides the power supply of the high-side
ground related section of the IC. An external capacitor
between pin 15 and 16 acts like a floating battery which
has to be recharged cycle by cycle via high voltage
diode from low-side supply voltage during on-time of
the low-side MOSFET. There is an UVLO threshold
with hysteresis that enables high-side section at 10,1V
and disables it at 8,4V.
HSGD (High side gate drive, Pin 19)
The Gate of the high-side MOSFET in a half-bridge
inverter 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. The switching
characteristics are the same as described for LSGD
(pin 2). It is recommended to use a resistor of about
15Ohm 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 LSGD signal and HSGD signal
is 1800ns typically.
HSGND (High side ground, Pin 20)
This pin is internally connected with pin 15.
Preliminary Datasheet Version 1.5
7
June 2005