ICE3AR1580VJZ Datasheet, PDF (19/43 Pages) Infineon Technologies AG – Of f -Line SMPS Cur rent Mode Cont rol ler wi th integrated 800V

3.6.1
Leading Edge Blanking
V_Sense
Vcsth
tLEB = 220ns/180ns
CoolSET™ F3R80
ICE3AR1580VJZ
Functional Description
t
Figure 19: Leading Edge Blanking
Whenever the integrated CoolMOS™ is switched on, a leading edge spike is generated due to the primary-side
capacitances and reverse recovery time of the secondary-side rectifier. This spike can cause the gate drive to
switch off unintentionally. In order to avoid a premature termination of the switching pulse, this spike is blanked out
with a time constant of t_LEB = 220ns for normal load and t_LEB = 180ns for burst mode.
3.6.2 Propagation Delay Compensation (patented)
In case of overcurrent detection, there is always propagation delay to switch off the integrated CoolMOS™. An
overshoot of the peak current _Ipeak is induced to the delay, which depends on the ratio of dI/ dt of the peak
current (Figure 20).
I_Sense
I_peak2
I_peak1
I_Limit
Signal2
I_Overshoot2
Signal1
t_{Propagation Delay}
I_Overshoot1
t
Figure 20: Current Limiting
The overshoot of Signal2 is larger than of Signal1 due to the steeper rising waveform. This change in the slope
is depending on the AC input voltage. Propagation Delay Compensation is integrated to reduce the overshoot
due to dI/dt of the rising primary current. Thus the propagation delay time between exceeding the current sense
threshold _Vcsth and the switching off of the integrated CoolMOS™ is compensated over temperature within a wide
input range. Current Limiting is then very accurate.
For example, I_peak = 0.5A with R_Sense = 2. The current sense threshold is set to a static voltage level V_csth=1V without
Propagation Delay Compensation. A current ramp of dI/dt = 0.4A/µs, or dVSense/dt = 0.8V/µs, and a propagation
delay time of t_{Propagation Delay} =180ns leads to an I_peak overshoot of 14.4%. With the propagation delay compensation,
the overshoot is only around 2% (Figure 21).
Figure 21:
Data Sheet
V
1,3
1,25
1,2
1,15
1,1
1,05
1
0,95
0,9
0
with compensation
without compensation
0,2 0,4 0,6 0,8
1 1,2 1,4 1,6 1,8
dV_Sense
dt
2_V
s
Overcurrent Shutdown
19
V2.0, 2014-01-20