ICE3GS03LJG Datasheet, PDF (16/25 Pages) Infineon Technologies AG – Of f-Line SMPS Current Mode Controller wi th integrated 500V Startup Cell

F3 PWM controller
ICE3GS03LJG
Functional Description
3.7.3
Protection Modes
The IC provides several protection features which are
separated into two categories. Some enter Latched Off
Mode and the others enter Auto Restart Mode. Besides
the pre-defined protection feature for the Latch off
mode, there is also an external Latch off Enable pin for
customer defined Latch off protection features. The
Latched Off Mode can only be reset if VCC falls below
6.23V. Both modes prevent the SMPS from destructive
states.The following table shows the relationship
between possible system failures and the chosen
protection modes.
VCC Overvoltage
Latched Off Mode
Overtemperature
Latched Off Mode
Short Winding/Short Diode Latched Off Mode
External Protection Enable Latched Off Mode
Overload
Auto Restart Mode
Open Loop
Auto Restart Mode
VCC Undervoltage
Auto Restart Mode
The VCC voltage is observed by comparator C2. If the
VCC voltage is > 25.5V and last for 120ms, the
overvoltage detection is activated. It enters the latch off
mode.This protection mode is activated in both normal
operating mode and burst mode.
The internal Voltage Reference is switched off most of
the time once Latched Off Mode is entered in order to
minimize the current consumption of the IC. This
Latched Off Mode can only be reset if the V_VCC < 6.23V.
In this mode, only the UVLO is working which controls
the Startup Cell by switching on/off at V_VCCon/V_VCCoff.
During this phase, the average current consumption is
only 250mA. As there is no longer a self-supply by the
auxiliary winding, the VCC drops. The Undervoltage
Lockout switches on the integrated Startup Cell when
VCC falls below 10.5V. The Startup Cell is switched off
again when VCC has exceeded 18V. Once the Latched
Off Mode was entered, there is no Start Up Phase
whenever the VCC exceeds the switch-on level of the
Undervoltage Lockout. Therefore the VCC voltage
changes between the switch-on and switch-off levels of
the Undervoltage Lockout with a saw tooth shape (see
Figure 26).
Short Optocoupler
Auto Restart Mode
V_VCC
3.7.3.1 Latched Off Mode
CS
1.66V ^C11
Spike
Blanking
190ns
LatchedOff
ModeReset
V_VCC <6.23V
18V
10.5V
UVLO
1
2ms
G3
counter
BL
T_LE
#
30us
C9
Blanking
Time
0.33V
Latch
Enable
signal
VCC
120us &
C2
Blanking
25.5V
Time
G1
Latched
Off Mode
Spike
Blanking
30us
Thermal Shutdown
T_j >130°C
Voltage
Reference
Control Unit
Figure 25 Latched Off Mode
I_VCCStart
t
0.9mA
t
Figure 26 Signals in Latched Off Mode
The Thermal Shutdown block monitors the junction
temperature of the IC. After detecting a junction
temperature higher than latched thermal shutdown
temperature; T_jSD, the Latched Off Mode is entered.
The signals coming from the temperature detection and
VCC overvoltage detection are fed into a spike
blanking with a time constant of 30ms in order to
ensure the system reliability.
Furthermore, a short winding or short diode on the
secondary side can be detected by the comparator C11
which is in parallel to the propagation delay
compensated current limit comparator C10. In normal
Version 2.0
16
1 Nov 2010