ICB2FL02G Datasheet, PDF (21/55 Pages) Infineon Technologies AG – Smart Ballast Control IC for Fluorescent Lamp Ballasts

2^nd Generation FL-Controller for FL-Ballasts
Functional Description
2.4.2 PFC Bus Voltage Sensing
Over voltage, open loop, bus 95 % and under voltage states (Figure 15) of the PFC bus voltage are
sensed at the PFCVS pin via the network R14, R15, R20 and C11 Figure 3 (C11 acts as a spike
suppression filter).
2.4.2.1
Bus Over Voltage and PFC Open Loop
The bus voltage loop control is completely integrated (Figure 16) and provided by an 8 Bit sigma –
delta A/D – converter with a typical sampling rate of 280 µs and a resolution of 4 mV/Bit. After leaving
phase 2 (monitoring), the IC starts the power up (VCC > 14.1V). After power up, the IC senses for
130µs the bus voltage below 12.5% (open loop) or above 105% (bus over voltage). In case of a bus
over voltage (V_BUSrated > 109 %) or open loop (V_BUSrated < 12.5 %) in phases 3 until 8 the IC shuts off
the gate drives of the PFC within 5µs respective in 1µs. In this case, the PFC restarts automatically
when the bus voltage is within the corridor (12.5% < V_BUSrated < 105 %) again. Is the bus voltage after
the 130µs valid, the bus voltage sensing is set to 12.5% < V_BUSrated < 109 %. In case leaving these
thresholds for longer than 1µs (open loop) or 5µs (overvoltage) the PFC gate drive stops working until
the voltage drops below 105% or exceeds the 12.5% level. If the bus over voltage (>109%) lasts for
longer than 625ms in run mode, the inverter gates also shut off and a power down with complete
restart is attempt (Figure 15).
Figure 15 PFC Bus Voltage Operating Level and Error Detection
2.4.2.2
Bus Voltage 95% and 75% Sensing
When the rated bus voltage is in the corridor of 12.5% < V_BUSrated < 109 %, the IC will check whether
the bus voltage exceeds the 95 % threshold (Figure 15 phase 3) within 80 ms before entering the soft
start phase 4. Another threshold is activated when the IC enters the run mode (phase 8). When the
rated bus voltage drops below 75% for longer than 84 µs, a power down with a complete restart is
attempted when a counter exceeds 800 ms. In case of a short term bus under voltage (the bus voltage
reaches its working level in run mode before exceeding typically 800 ms (min. 500ms) the IC skips
phases 1 until 5 and starts with ignition (condition for emergency lighting see 2.7.1). The internal
reference level of the bus voltage sense V_PFCVS is 2.5 V (100 % of the rated bus voltage) with a high
accuracy. A surge protection is activated in case of a rated bus voltage of V_BUS > 109% and a low side
current sense voltage of V_LSCS > 0.8V for longer as 500ns in PRE RUN and RUN Mode.
Preliminary Datasheet
Page 21 of 55
ICB2FL02G
V1.2