CCM-PFC
ICE2PCS01/G
Functional Description
3.4
System Protection
The IC provides several protection features in order to
ensure the PFC system in safe operating range.
Depending on the input line voltage (VIN) and output
bus voltage (VOUT), Figure 7 and 8 show the conditions
when these protections are active.
Normal Control
VOUT =rated
Window Detect
Max Vcomp current
VOUT
95%rated
83%rated
VCC > VCCUVLO
VCC<VCCUVLO
VIN (VAC)
t
Level-shifted VCOMP
av(IIN)
t
Normal
Operation
IC’s
IC OFF
State
VCOMP
t
Figure 6
VIN Related Protection Features
VOUT
VOUT,Rated
Figure 5
Startup with controlled maximum current
108%
100%
20%
t
PCL / SOC
OVP
OLP
OLP
Figure 7
VOUT Related Protection Features
The following sections describe the functionality of
these protection features.
3.4.1
Soft Over Current Control (SOC)
The IC is designed not to support any output power
that corresponds to a voltage lower than -0.75V at the
ISENSE pin. A further increase in the inductor current,
which results in a lower ISENSE voltage, will activate
the Soft Over Current Control (SOC). This is a soft
control as it does not directly switch off the gate drive.
It acts on the nonlinear gain block to result in a reduced
PWM duty cycle.
Version 2.2
8
09 October 2007
INFINEON [ Infineon ]
