ICE1PCS01 Datasheet, PDF (7/18 Pages) Infineon Technologies AG – Standalone Power Factor Correction (PFC) Controller in Continuous Conduction Mode (CCM)

Preliminary Data
3
Functional Description
CCM-PFC
ICE1PCS01/G
Functional Description
3.1 General
The ICE1PCS01/G is a 8 pin control IC for power factor
correction converters. It comes in both DIP and DSO
packages and is suitable for wide range line input
applications from 85 to 265 VAC. The IC supports
converters in boost topology and it operates in
continuous conduction mode (CCM) with average
current control.
The IC operates with a cascaded control; the inner
current loop and the outer voltage loop. The inner
current loop of the IC controls the sinusoidal profile for
the average input current. It uses the dependency of
the PWM duty cycle on the line input voltage to
determine the corresponding input current. This means
the average input current follows the input voltage as
long as the device operates in CCM. Under light load
condition, depending on the choke inductance, the
system may enter into discontinuous conduction mode
(DCM). In DCM, the average current waveform will be
distorted but the resultant harmonics are still low
enough to meet the Class D requirement of IEC 1000-
3-2.
The outer voltage loop controls the output bus voltage.
Depending on the load condition, OTA1 establishes an
appropriate voltage at VCOMP pin which controls the
amplitude of the average input current.
The IC is equipped with various protection features to
ensure safe operating condition for both the system
and device. Important protection features are namely
Brown-out protection, Current Limitation and Output
Under-voltage Protection.
3.2 Power Supply
An internal under voltage lockout (UVLO) block
monitors the VCC power supply. As soon as it exceeds
11.2V and the voltage at pin 6 (VSENSE) is >0.8V, the
IC begins operating its gate drive and performs its Soft-
Start as shown in Figure 3.
.
V_CC
11.2 V
V_VSENSE
> 0,8 V
V_VSENSE
< 0,8 V
V_VSENSE
> 0,8 V
10.5 V
If VCC drops below 10.2V, the IC is off. The IC will then
be consuming typically 200µA, whereas consuming
18mA during normal operation.
The IC can be turned off and forced into standby mode
by pulling down the voltage at pin 6 (VSENSE) to lower
than 0.8V. The current consumption is reduced to 3mA
in this mode.
3.3 Start-up (Soft-Start)
Figure 4 and 5 show the operation of OTA1 during
startup. It sources a constant 10.8µA into the
compensation network at pin 5 (VCOMP). The voltage
at this pin rises linearly and so does the amplitude of
the input current. As soon as the output voltage V_OUT
reaches 80% of its rated level, the startup procedure is
finished and the normal voltage control takes over. In
normal operation, the IC operates with a higher
maximum current at OTA1 and therefore with a higher
voltage loop gain in order to improve the dynamic
behavior of the device.
.
VSENSE
R4
( _{R3 + R4} x V_OUT )
Soft Start
4.0V
10.8uA during
Soft Start
VCOMP
S1
R6
OTA1
5V
C3
Open-Loop
0.8V
Protect
(OLP)
C4
C5 _ICE1PCS01/G
Figure 4 Soft Start Circuit
Soft Start
Normal Operation
V_OUT < 80% rated V_OUT > 80% rated
av(I_IN)
t
IC's
State
OFF
Soft Normal
start Operation
Open loop/
Standby
Normal
Operation
OFF
Figure 3 State of Operation respect to VCC
t
Figure 5 Soft Start with controlled current
The advantage of this technique is a soft-start function
with lower stress for the boost diode but without the risk
of audible noise.
Preliminary Datasheet
7
28 May 2003