ICL5101_16 Datasheet, PDF (14/44 Pages) Infineon Technologies AG – Resonant controller IC with PFC for LED driver

ICL5101
Functional Description
When V_CC exceeds the 14.0 V threshold – by the end of the start-up hysteresis – the IC waits for 80 µs and
senses the bus voltage. When the rated bus voltage is in the corridor of 12.5 % < V_BUSrated < 105 %, the IC
powers up. The IC initiates an UVLO when the chip supply voltage is below V_CC < 10.6 V. As soon as the
condition of a power-up is fulfilled, the IC starts the inverter gate operation with an internal fixed start-up
frequency of 135 kHz. The PFC gate drive starts with a delay of app. 300 µs. Then the bus voltage will be
checked for a rated level above 95 % for duration of 80 ms. Now, the IC enters the soft start phase and shifts
the frequency from the internal fixed start-up frequency of 135 kHz down to the set RUN frequency.
2.1.2
Soft Start to Run Mode
This section describes the operating flow from soft start to run mode in detail. After the soft start phase is
finished, the saturation control phase is entered.
Figure 7 Start-Up Procedure from Soft Start to Run Mode
During saturation control ( Start-Up Procedure from Soft Start to Run ModeFigure 7), the operating frequency of
the inverter is shifted downward in t_typ = 40 ms to the run frequency set by a resistor at the pin RFM to GND.
The saturation 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 decreasing and signifies waiting for an adequate
output voltage. The saturation control is now continuously monitored by the LSCS pin. The maximum duration of
the saturation control procedure is limited to 237 ms. If there is still saturation within this time frame, the
saturation control is disabled and the IC changes over to the latched fault mode. Furthermore, in order to reduce
the choke size, the saturation control is designed to operate with a choke in magnetic saturation of the
RESONANT during start-up. For an operation in magnetic saturation during saturation control mode, the voltage
at the shunt at the LSCS pin 2 has to be V_LSCS = 0.80 V when the output voltage is reached. If the saturation
control mode is successfully passed, the IC enters the extended saturation mode The extended saturation mode
is a safety mode used in order to prevent a malfunction of the IC due to an instable system. After 625 ms, the IC
changes to the run mode (Figure 7). The run mode monitors the complete system regarding bus over- and
under voltage, open loop, overcurrent of PFC and/or inverter, output overvoltage, over temperature and
capacitive load operation.
Datasheet
14
Rev. 1.3, 2016-01-15