ICE3A1065ELJ Datasheet, PDF (18/29 Pages) Infineon Technologies AG – Off-Line SMPS Current Mode Controller with integrated 650V CoolMOS

CoolSET^®-F3
ICE3A1065ELJ
Functional Description
Furthermore, a short winding or short diode on the
secondary side can be detected by the comparator C11
which is in parallel to the propagation delay
compensated current limit comparator C10. In normal
operating mode, comparator C10 controls the
maximum level of the CS signal at 1.06V. If there is a
failure such as short winding or short diode, C10 is no
longer able to limit the CS signal at 1.06V. Instead the
comparator C11 detects the peak current voltage >
1.66V and enters the Latched Off Mode immediately in
order to keep the SMPS in a safe stage.
In case the pre-defined Latch Off features are not
sufficient, there is a customer defined external Latch
Enable feature. The Latch Off Mode can be triggered
by pulling down the BL pin to < 0.1V. It can simply add
a trigger signal to the base of the externally added
transistor, T_LE at the BL pin. To ensure this latch
function will not be mis-triggered during start up, a 1ms
delay time is implemented to blank the unstable signal.
3.7.3.2 Auto Restart Mode
to charge the capacitor C_BK from 0.9V to 4.0V after the
switch S1 is released. The charging time from 0.9V to
4.0V are the extendable blanking time. If C_BK is 0.22uF
and I_BK is 8.4uA, the extendable blanking time is
around 80ms and the total blanking time is 100ms. In
combining the FB and blanking time, there is a blanking
window generated which prevents the system to enter
Auto Restart Mode due to large load jumps.
In case of VCC undervoltage, the IC enters into the
Auto Restart Mode and starts a new startup cycle.
Short Optocoupler also leads to VCC undervoltage as
there is no self supply after activating the internal
reference and bias.
In contrast to the Latched Off Mode, there is always a
Startup Phase with switching cycles in Auto Restart
Mode. After this Start Up Phase, the conditions are
again checked whether the failure mode is still present.
Normal operation is resumed once the failure mode is
removed that had caused the Auto Restart Mode.
BL
# ^C_BK
I_BK
0.9V
1
S1
G2
5.0V
C3
4.0V
Spike
Blanking
8.0us
4.5V
FB
C4
&
20ms
G5
Blanking
Time
Auto
Restart
Mode
Control Unit
Figure 27 Auto Restart Mode
In case of Overload or Open Loop, the FB exceeds
4.5V which will be observed by comparator C4. Then
the internal blanking counter starts to count. When it
reaches 20ms, the switch S1 is released. Then the
clamped voltage 0.9V at V_BL can increase. When there
is no external capacitor C_BK connected, the V_BL will
reach 4.0V immediately. When both the input signals at
AND gate G5 is positive, the Auto-Restart Mode will be
activated after the extra spike blanking time of 8.0us is
elapsed. However, when an extra blanking time is
needed, it can be achieved by adding an external
capacitor, C_BK. A constant current source of I_BK will start
Version 2.1
18
12 May 2009