ICE3A1065 Datasheet, PDF (12/32 Pages) Infineon Technologies AG – Off-Line SMPS Current Mode Controller with integrated 650V Startup Cell/ Depletion CoolMOS™

CoolSET™-F3
Functional Description
The internal Voltage Reference is switched off if Auto
Restart Mode is entered. The current consumption is
then reduced to 300mA.
Once the malfunction condition is removed, this block
will then turn back on. The recovery from Auto Restart
Mode does not require disconnecting the SMPS from
the AC line.
When Active Burst Mode is entered, the internal Bias is
switched off in order to reduce the current consumption
to below 1.05mA while keeping the Voltage Reference
active as this is necessary in this mode.
DC_max which is controlled by comparator C7 since
comparator C2 blocks the gate G7 (see Figure 7). This
maximum charge current in the very first stage when
V_SoftS is below 1V, is limited to 1.32mA.
V_SoftS
5.4V
4V
max. Startup Phase
3.3
Startup Phase
1V
max. Soft Start Phase
6.5V
3.25k
DC_max
t
R_SoftS
T2
DC₁
DC₂
T3
1V
SoftS
C_SoftS
Soft Start
C7
Soft-Start
Comparator
&
G7
Gate Driver
C2
4V
0.85V
x3.7
CS
PWMOP
t1
t2 t
Figure 8 Startup Phase
By means of this extra charge stage, there is no delay
in the beginning of the Startup Phase when there is still
no switching. Furthermore Soft Start is finished at 4V to
have faster the maximum power capability. The duty
cycles DC₁ and DC₂ are depending on the mains and
the primary inductance of the transformer. The
limitation of the primary current by DC₂ is related to
V_SoftS = 4V. But DC₁ is related to a maximum primary
current which is limited by the internal Current Limiting
with CS = 1V. Therefore the maximum Startup Phase
is divided into a Soft Start Phase until t1 and a phase
from t1 until t2 where maximum power is provided if
demanded by the FB signal.
Figure 7 Soft Start
At the beginning of the Startup Phase, the IC provides
a Soft Start duration whereby it controls the maximum
primary current by means of a duty cycle limitation. A
signal V_SoftS which is generated by the external
capacitor C_Softs in combination with the internal pull up
resistor R_SoftS, determines the duty cycle until V_SoftS
exceeds 4V.
When the Soft Start begins, C_SoftS is immediately
charged up to approx. 1V by T2. Therefore the Soft
Start Phase takes place between 1V and 4V. Above
V_SoftsS = 4V there is no longer duty cycle limitation
Version 2.3
12
02 Apr 2013