CoolSET™-F2
ICE2A165/265/365
ICE2A180/280
Functional Description
But the Soft-Start Phase must be finished within the detection due to varying of VCC concerning the
Start Up Phase to force the voltage at pin FB below the regulation of the converter output. When the voltage
failure detection threshold of 4.8V.
VSoftS is above 4.0V the overvoltage detection by C1 is
deactivated.
3.8.2
Overvoltage due to open loop with
no load
VCC
Open loop & no load condition
5µs Blanking
6.5V
FB
Error Latch
C1
C2
G 1
16.5V
4.8V
RSoft-Start
Failure
Detection
4.0V
SoftS
t
Soft-Start Phase
CSoft-Start
SoftS
T1
Power Up Reset
5.3V
4.0V
Overvoltage
Detection Phase
Figure 21 Overvoltage Detection
t
TBurst2
Driver
TRestart
3.8.3
Thermal Shut Down
Thermal Shut Down is latched by the Error-Latch when
junction temperature Tj of the pwm controller is
exceeding an internal threshold of 140°C. In that case
the IC switches in Auto Restart Mode.
t
O vervoltage Detection
VCC
16.5V
13.5V
8.5V
t
Figure 20 Auto Restart Mode
Figure 20 shows the Auto Restart Mode for open loop
and no load condition. In case of this failure mode the
converter output voltage increases and also VCC. An
additional protection by the comparators C1, C2 and
the AND-gate G1 is implemented to consider this
failure mode (see Figure 21).The overvoltage detection
is provided by Comparator C1 only in the first time
during the Soft-Start Phase till the Soft-Start voltage
exceeds the threshold of the Comparator C2 at 4.0V
and the voltage at pin FB is above 4.8V. When VCC
exceeds 16.5V during the overvoltage detection phase
C1 can set the Error-Latch and the Burst Phase during
Auto Restart Mode is finished earlier. In that case
TBurst2 is shorter than TSoft-Start . By means of C2 the
normal operation mode is prevented from overvoltage
Note: All the values which are mentioned in the
functional description are typical. Please refer
to Electrical Characteristics for min/max limit
values.
Datasheet
13
September 2001
INFINEON [ Infineon ]
