ICE2QS03G Infineon Technologies, ICE2QS03G Datasheet - Page 9

• Manufacturer Part Number: ICE2QS03G
• Description: IC CTRLR PWM QUASI-RESON DSO8
• Manufacturer: Infineon Technologies

Specifications of ICE2QS03G

• Output Isolation: Isolated
• Frequency Range: 52kHz
• Voltage - Input: 11.2 V ~ 27 V
• Operating Temperature: -25°C ~ 130°C
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

thedetected zero-crossing to the switch-on of the main
switch t
This time delay should be matched by adjusting the
time constant of the RC network which is calculated as:
3.3.2
After MOSFET is turned off, there will be some
oscillation on V
on ZC pin. To avoid that the MOSFET is turned on
mistriggerred
suppression timer is implemented. The timer is
dependent on the voltage v
lower than the threshold V
applies, while a shorter time is set when the voltage v
is higher than the threshold.
3.3.2.1
After the gate drive goes to low, it can not be changed
to high during ring suppression time.
After ring suppression time, the gate drive can be
turned on when the ZC counter value is higher or equal
to up/down counter value.
However, it is also possible that the oscillation between
primary inductor and drain-source capacitor damps
very fast and IC can not detect enough zero crossings
and ZC counter value will not be high enough to turn on
the gate drive. In this case, a maximum off time is
implemented. After gate drive has been remained off
for the period of T
again regardless of the counter values and V
function
frequency from going lower than 20kHz, otherwise
which will cause audible noise, during start up.
3.3.3
In the converter system, the primary current is sensed
by an external shunt resistor, which is connected
between low-side terminal of the main power switch
and the common ground. The sensed voltage across
the shunt resistor v
measurement unit, and its output voltage V
compared with the regulation voltage V
voltage V
is reset. As a result, the main power switch is switched
off. The relationship between the V
described by:
Version 2.1
V
τ
∆t
td
1
=
=
=
T osc
------------ t
3.3 V
delay
C
4
zc
1
can
⋅
exceeds the voltage V
, theoretically:
Ringing suppression time
Switch on determination
Switch Off Determination
⋅
–
-------------------------------- -
R
CS
R zc1 R zc2
zc1
delay
DS
by
effectively
+
, which will also appear on the voltage
OffMax
0.7
+
⋅
CS
R
such
zc2
, the gate drive will be turned on
is applied to an internal current
ZC
ZCRS
oscillations,
prevent
. When the voltage v
, a longer preset time
FB
, the output flip-flop
1
and the v
the
FB
. Once the
a
switching
ZC
ringing
. This
CS
1
ZC
[2]
[3]
[4]
ZC
is
is
is
9
To avoid mistriggering caused by the voltage spike
across the shunt resistor at the turn on of the main
power switch, a leading edge blanking time, t
applied to the output of the comparator. In other words,
once the gate drive is turned on, the minimum on time
of the gate drive is the leading edge blanking time.
In addition, there is a maximum on time, t
limitation implemented in the IC. Once the gate drive
has been in high state longer than the maximum on
time, it will be turned off to prevent the switching
frequency from going too low because of long on time.
3.3.4
The drive-stage is optimized for EMI consideration. The
switch on speed is slowed down before it reaches the
CoolMOS
the rising edge at the output of driver(see
Thus the leading swich spike during turn on is
minimized.
Figure 6
3.4
There is a cycle by cycle current limitation realized by
the current limit comparator to provide an overcurrent
detection. The source current of the MOSFET is
sensed via a sense resistor R
source current is transformed to a sense voltage V
which is fed into the pin CS. If the voltage V
an internal voltage limit, adjusted according to the
Mains voltage, the comparator immediately turns off
the gate drive.
To prevent the Current Limitation process from
distortions caused by leading edge spikes, a Leading
Edge Blanking time (t
sensing path.
A further comparator is implemented to detect
dangerous current levels (V
one or more transformer windings are shorted or if the
secondary diode is shorted. To avoid an accidental
latch off, a spike blanking time of t
the output path of the comparator.
Quasi-Resonant PWM Controller
®
turn on threshold.That is a slope control of
Modulated gate drive
Current Limitation
Gate rising waveform
LEB
Functional Description
) is integrated in the current
CSSW
CS
. By means of R
) which could occur if
CSSW
February 5, 2010
ICE2QS03G
is integrated in
CS
Figure
exceeds
LEB
CS
OnMax
, is
the
CS
6.
,