ICE3DS01L Datasheet, PDF (9/27 Pages) Infineon Technologies AG – Off-Line SMPS Current Mode Controller with integrated 500V Startup Cell

F3
ICE3DS01L/LG
Functional Description
controller can only take place after Active Mode was
entered and V_VCC falls below 8.5V.
The maximum current consumption before the
controller is activated is about 170µA.
When V_VCC falls below the off-threshold V_CCoff=8.5V the
internal reference is switched off and the Power Down
reset let T1 discharging the soft-start capacitor C_SoftS at
pin SoftS. Thus it is ensured that at every startup cycle
the voltage ramp at pin SoftS starts at zero.
The internal Voltage Reference is switched off if
Latched Off Mode or Auto Restart Mode is entered.
The current consumption is then reduced to 300µA.
When Active Burst Mode is entered the internal Bias is
switched off in order to reduce the current consumption
below 1.1mA while keeping the Voltage Reference still
active as this is necessary in this mode.
In case Latched Off Mode is entered VCC needs to be
lowered below 6V to reset the Latched Off Mode. This
is done usually by disconnecting the SMPS from the
AC line.
capacitor C_Softs in combination with the internal pull up
resistor R_SoftS determines the duty cycle until V_SoftS
exceeds 4V.
In the beginning 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 DC_max is controlled by
comparator C7 as comparator C2 blocks the gate G7
(see Figure 6).The maximum charge current in the very
first phase when V_SoftS is below 1V is limited to 1.9mA.
V_SoftS
5.4V
4V
max. Startup Phase
1V
max. Soft Start Phase
3.3
Startup Phase
DC_max
t
6.5V
DC₁
3.25k
DC₂
SoftS
R_SoftS
T2
T3
1V
C_SoftS
Soft Start
C7
Soft-Start
Comparator
&
G7
Gate Driver
C2
4V
0.85V
x3.7
CS
PWM OP
t1
t2 t
Figure 6 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 5 Soft Start
During the Startup Phase a Soft Start is provided. A
signal V_SoftS which is generated by the external
Version 2.0
9
15 May 2003