ICLS6022J Datasheet, PDF (19/33 Pages) Infineon Technologies AG – LED System Driver ICs

LED System Driver ICs
ICLS6x Series
Functional Description
3.5.1 Leading Edge Blanking
Each time when the integrated internal CoolMOS™ is switched on, a leading edge spike is generated due to the
primary-side capacitances and secondary-side rectifier reverse recovery time. This spike can cause the gate drive
to switch off unintentionally. To avoid premature termination of the switching pulse, this spike is blanked out with
a time constant of t_LEB = 220 ns. During this time, the gate drive will not be switched off. This is illustrated in
Figure 11.
V_Sense
V_{c s th}
t_LEB = 220ns
t
Figure 11 Leading edge blanking
3.5.2 Propagation Delay Compensation
In the case of overcurrent detection, switch-off of the integrated internal CoolMOS™ is delayed due to the
propagation delay of the circuit. This delay causes an overshoot of the peak current I_peak, which depends on the
ratio of dI/dt of the peak current (see Figure 12).
I_Sense
I_peak2
I_peak1
I_Limit
Signal2
I_{Overshoot 2}
Signal1
t_{Propagation Delay}
I_{Overshoot 1}
t
Figure 12 Peak current overshooting
The overshoot of Signal2 is greater than that of Signal1 due to the steeper rising waveform. This change in the
slope varies according to the AC input voltage. A Propagation Delay Compensation circuit is integrated to limit the
overshoot dependency on dI/dt of the rising primary current. This means that the propagation delay between the
time the current sense threshold V_csth is exceeded and switch-off of the integrated inernal CoolMOS™ is
compensated over temperature within a wide range.
Data Sheet
19
Version 1.0, 2011-05-19