ICLS6022J Datasheet, PDF (14/33 Pages) Infineon Technologies AG – LED System Driver ICs

3.2
Power Management
LED System Driver ICs
ICLS6x Series
Functional Description
Drain
Startup Cell
VCC
Power Management
Internal Bias
Power -Down Reset
Undervoltage Lockout
18V
10 . 3
5V
Voltage
Reference
Auto Restart
Mode
T1
SoftS
Figure 5 Power management of ICLS6x Series controllers
The undervoltage lockout function monitors the external supply voltage V_VCC. When the LED drive is connected to
the main line, the internal startup cell is biased and starts to charge the external capacitor C_VCC, which is connected
to the VCC pin. The VCC charge current that is provided by the startup cell from the drain pin is 1.05 mA. If V_VCC
exceeds the on-threshold V_CCon (= 18 V), the bias circuit is switched on. Then the startup cell is switched off by the
undervoltage lockout; therefore no power losses are present due to the connection of the startup cell to the drain
voltage. An hysteresis loop is implemented to avoid uncontrolled ringing at switch-on. Switch-off of the controller
can only take place after the active mode has been entered and V_VCC has fallen below 10.3 V.
The maximum current consumption before the controller is activated is about 300 µA.
If V_VCC falls below the off-threshold V_CCoff (= 10.3 V), the bias circuit is switched off and a power-down reset causes
discharging of the soft-start capacitor C_SoftS at pin SoftS via T4 (see Figure 5). This ensures in every startup cycle
that the voltage ramp at the SoftS pin starts at zero.
The bias circuit is switched off if Auto Restart mode is entered. The current consumption is then reduced to 300 µA.
Once the malfunction condition is resolved, this block will then turn back on. The recovery from Auto Restart mode
does not require disconnection of the LED drive from the AC line.
Data Sheet
14
Version 1.0, 2011-05-19