ICE3BS03LJG Datasheet, PDF (10/25 Pages) Infineon Technologies AG – Off-Line SMPS Current Mode Controller with integrated 500V Startup Cell

5V
R_FB
Soft-Start Comparator
FB
PWM-Latch
C8
PWM Comparator
F3 PWM controller
ICE3BS03LJG
Functional Description
is a built-in function and it is controlled by an internal
counter.
Optocoupler
0.6V
PWM OP
CS
X3.2
Improved
Current Mode
V_SoftS
V_SoftS2
V_SoftS1
Figure 8 PWM Controlling
3.4
Startup Phase
Soft S tart counter
S o ftS
Soft Start
Soft Start
S o ft-S ta rt
C om parator
C7
&
G7
G ate D river
Figure 10 Soft Start Phase
When the V_VCC exceeds the on-threshold voltage, the
IC starts the Soft Start mode (see Figure 10).
The function is realized by an internal Soft Start
resistor, an current sink and a counter. And the
amplitude of the current sink is controlled by the
counter (see Figure 11).
5V
SoftS
R_SoftS
Soft Start ^{32I 8I 4I 2I}
I
Counter
0.6V
x3.2
CS
PWM OP
Figure 9 Soft Start
In the Startup Phase, the IC provides a Soft Start
period to control the maximum primary current by
means of a duty cycle limitation. The Soft Start function
Figure 11 Soft Start Circuit
After the IC is switched on, the V_SFOFTS voltage is
controlled such that the voltage is increased step-
wisely (32 steps) with the increase of the counts. The
Soft Start counter would send a signal to the current
sink control in every 600us such that the current sink
Version 2.0
10
6 Dec 2007