ICE2QS01 Datasheet, PDF (11/17 Pages) Infineon Technologies AG – Quasi-resonant PWM Controller

3.5
Protection Functions
The IC provides full protection functions. The following
table summarizes these protection functions.
Table 2 Protection features
VCC Overvoltage
Auto Restart Mode
VCC Undervoltage
Auto Restart Mode
Overload/Open Loop
Auto Restart Mode
Output Overvoltage
Latched Off Mode
Short Winding
Latched Off Mode
During operation, the VCC voltage is continuously
monitored. In case of an under- or an over-voltage, the
IC is reset and the main power switch is then kept off.
After the VCC voltage falls below the threshold
V_VCCUVP, the power cell is activated. The VCC capacitor
is then charged up. Once the voltage exceeds the
threshold V_VCCon, the IC begins to operate with a new
soft-start.
In case of open control loop or output over load, the
regulation voltage will be pulled up . After a blanking
time of 24ms, the IC enters auto-restart mode. The
blanking time here enables the converter to provide a
high power in case the increase in V_REG is due to a
sudden load increase. During off-time of the power
switch, the voltage at the zero-crossing pin is
monitored for output over-voltage detection. If the
voltage is higher than the preset threshold v_OPOVP, the
IC is latched off after the preset blanking time.
If the voltage at the current sensing pin is higher than
the preset threshold v_csSW during on-time of the power
switch, the IC is latched off. This is short-winding
protection.
During latch-off protection mode, the power cell is
activated and it keeps the VCC voltage at the level of
V_VCCBL.
Quasi-Resonant PWM Controller
ICE2QS01
Functional Description
Version 2.1
11
October 2007