CCM-PFC
ICE3PCS01G
Functional Description
Version 3.0 8 03 April 2017
3 Functional
Description
3.1 General
The ICE3PCS01G is a 14-pins control IC for power
factor correction converters. It is suitable for wide range
line input applications from 85 to 265 VAC with overall
efficiency above 90%. 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) resulting in a higher harmonics but still meeting
the Class D requirement of IEC 1000-3-2.
The outer voltage loop controls the output bulk voltage,
integrated digitally within the IC. Depending on the load
condition, internal PI compensation output is converted
to an appropriate DC voltage 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.
3.2 Power Supply
An internal under voltage lockout (UVLO) block
monitors the VCC power supply. As soon as it exceeds
12.0V and both voltages at pin 11 (VSENSE) >0.5V
and pin 9 (BOP) >1.25V, the IC begins operating its
gate drive and performs its startup as shown in Figure
3.
If VCC drops below 11V, the IC is off. The IC will then
be consuming typically 1.4mA, whereas consuming
6.7mA during normal operation
The IC can be turned off and forced into standby mode
by pulling down the voltage at pin 11 (VSENSE) below
0.5V or the voltage at pin 7 (VBTHL_EN) below 0.5V.
Figure 3 State of Operation respect to VCC
3.3 Start-up
During power up when the Vout is less than 95% of the
rated level, internal voltage loop output increases from
initial voltage under the soft-start control. This results in
a controlled linear increase of the input current from 0A
thus reducing the stress in the external components.
Once Vout has reached 95% of the rated level, the soft-
start control is released to achieve good regulation and
dynamic response and VB_OK pin outputs 5V
indicating PFC stage in normal operation.
3.4 Frequency Setting and External
Synchronization
The IC can provide external switching frequency
setting by an external resistor R
FREQ
and the online
synchronization by external pulse signal at FREQ pin.
3.4.1 Frequency Setting
The switching frequency of the PFC converter can be
set with an external resistor R
FREQ
at FREQ pin as
shown Figure 2. The pin voltage at V
FREQ
is typical 1V.
The corresponding capacitor for the oscillator is
integrated in the device and the R
FREQ
/frequency is
given in Figure 4. The recommended operating
frequency range is from 21kHz to 100kHz. As an
example, a R
FREQ
of 67kΩ at pin FREQ will set a
switching frequency F
SW
of 65kHz typically.
UVLO
OVP
configuration
within 50us
VREF rises to 5V with
100nF external cap.
within 200us
Bulk voltage rises to 95% rated valu e
within 200ms
V
BULK
V
CC
I
VCC
V
REF
VB_OK
20%
95%
100%
12V
5V
5V
1.4mA
5 mA
<6.7mA
with 1nF external cap. at gate dr ive pin
26V
3.5mA
Normal
operation
Standby mode
(V
VSENSE
< 0.5V or V
VBTHL
< 0.5V)
