ICE2A280 Infineon Technologies Corporation, ICE2A280 Datasheet - Page 9

• Manufacturer Part Number: ICE2A280
• Manufacturer: Infineon Technologies Corporation

Figure 8
3.3
Figure 9
The Soft-Start is realized by the internal pullup resistor
R
Figure 2). The Soft-Start voltage V
charging the external capacitor C
Datasheet
Soft-Start
O p to co u p le r
5 .6 V
5 .3 V
V
G a te D rive r
and the external Capacitor C
S oftS
Soft-Start
PWM Controlling
Soft-Start Phase
F B
R
F B
T
S oft-S tart
6 .5 V
S o ft-S ta rt C o m p ara to r
P W M O P
P W M C o m p a rato r
0 .8 V
Im proved
Current M ode
Soft-Start
x3 .65
SoftS
P W M -L atch
is generated by
by the internal
Ise n se
Soft-Start
(see
t
t
9
pullup resistor R
compares the voltage at pin SoftS at the negative input
with the ramp signal of the PWM-OP at the positive
input. When Soft-Start voltage V
Feedback voltage V
the pulse width by reseting the PWM-Latch (see Figure
9). In addition to Start-Up, Soft-Start is also activated at
each restart attempt during Auto Restart. By means of
the above mentioned C
defined by the user. The Soft-Start is finished when
V
activated by Comparator C4 and senses the FB by
Comparator C3 wether the voltage is below 4.8V which
means that the voltage on the secondary side of the
SMPS is settled. The internal Zener Diode at SoftS with
breaktrough voltage of 5.6V is to prevent the internal
circuit from saturation (see Figure 10).
Figure 10
The Start-Up time T
voltage V
Start Phase T
By means of Soft-Start there is an effective
minimization of current and voltage stresses on the
integrated CoolMOS™, the clamp circuit and the output
overshoot and prevents saturation of the transformer
during Start-Up.
C
SoftS
S o ftS
5 .6 V
F B
Soft
6 .5 V
exceeds 5.3V. At that time the Protection Unit is
R
Start
5 .3 V
4 .8 V
F B
OUT
Activation of Protection Unit
6 .5 V
is settled must be shorter than the Soft-
Soft-Start
R
R
C 4
C 3
Soft-Start
S o ft-S ta rt
Soft
FB
Start-Up
(see Figure 11).
T
the Soft-Start-Comparator limits
Functional Description
Soft
Start
. The Soft-Start-Comparator
Soft-Start
C lo c k
P o w e r-U p R e s e t
ICE2A165/265/365
within the converter output
Start
G 2
, 1
the Soft-Start can be
CoolSET™-F2
ICE2A180/280
69
P W M -L a tc h
September 2001
E rro r-L a tc h
SoftS
R
R
S
S
is less than
Q
Q
Q
Q
G a te
D riv e r