ICE3GS03LJG Datasheet, PDF (10/25 Pages) Infineon Technologies AG – Of f-Line SMPS Current Mode Controller wi th integrated 500V Startup Cell

5V
R_FB
Soft-Start Comparator
FB
PWM-Latch
C8
PWM Comparator
F3 PWM controller
ICE3GS03LJG
Functional Description
is a built-in function and it is controlled by an internal
counter.
Optocoupler
0.67V
PWM OP
CS
X3.3
Improved
Current Mode
V_SoftS
V_SoftS2
V_SoftS1
Figure 8 PWM Controlling
3.4
Startup Phase
Soft Start counter
S o ftS
S oft Start
Soft S tart
S oft-Start
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 .6 7 V
x 3 .3
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 300us such that the current sink
Version 2.0
10
1 Nov 2010