NCP1654_09 ONSEMI [ON Semiconductor], NCP1654_09 Datasheet - Page 15

• Manufacturer Part Number: NCP1654_09
• Description: Power Factor Controller for Compact and Robust, Continuous Conduction Mode Pre-Converters
• Manufacturer: ONSEMI [ON Semiconductor]

R
V
R
V
Amplifier (OTA) senses V
dividers, R
voltage, V
V
V
PFC duty modulation is after decreasing a offset voltage,
V
that comes from the PFC output voltage V
varying signal. The bandwidth of I
additionally limited by inserting the external type−2
compensation components (that are R
shown in Figure 38). It is recommended to limit f
is the bandwidth of V
typically to achieve power factor correction purpose.
(Equation 12) if C
V
V
out
control
boL
in
boU
in
CONTROL(min)
CONTROL(min)
Refer to Figure 38, the Operational Trans−conductance
This control current I
The transformer of V
out
and BO pin.
and BO pin.
.
is low side resistor of the dividing resistors between
is upper side resistor of the dividing resistors between
The
+
R
R
R
control
CS
SENSE
R
fbU
fbL
fbL
operating
I
Figure 37. Current Sensing
@ G
CS
, i.e. V
) R
and R
, depending on the output power and hence
I
to V
L
Z
EA
V
is >> C
+
CS
−
I
fbU
CS
L
R
CONTROL(max)
fbL
Z
control
control
@
control
out
. The OTA constructs a control
sR
P
NCP1654
range
. G
out
−V
to V
Z
C
EA
1 ) sR
is a roughly constant current
(or I
CONTROL(min)
Z
Gnd
via the feedback resistor
(1 ) sR
C
control
is the error amplifier gain.
V
P
of V
in
. The signal used for
control
Z
R
C
fbL
is as described in
Z
Z
Z
control
out
, C
C
), below 20 Hz
control
P
that is a slowly
R
)
C
Z
V
.
Z
Figure 38. V
, and C
Z
control
6
5
control
is
+
can be
(eq. 12)
http://onsemi.com
V
R
fb
from
, that
fbU
V
P
REF
as
control
15
+
-
inductor current I
consists of the high−frequency component (that depends on
di/dt or inductor L) and low−frequency component (that is
I
where
R
R
Z
Z
in (Equation 14)
Z
high−frequency component of the multiplier voltage V
The high−frequency component is basically coming from
the inductor current I
capacitor C
component of inductor current I
C
I
over the bandwidth of 50 or 60 Hz and power factor is
corrected.
Low−Pass Filtering
L−50
L
in
in
SENSE
CS
in
filter
Refer to Figure 37, sense current I
From (Equation 7) − (Equation 11), the input impedance
When I
The multiplier capacitor C
OTA
becomes I
+
+
±20 mA
is re−formulated in (Equation 13).
is the offset resistor between CS pin and R
).
match with each other in terms of filtering capability,
2pR
2pR
is the sense resistor to sense I
L
CS
CS
is equal to I
filter
L−50
@ (V
@ (V
+
2 R
. Input impedance Z
control
control
2 R
similarly removes the high−frequency
M
L
R
To Vm Pin
M
I
V
cs
as described in (Equation 11). I
SENSE
out
+
R
L−50
* V
* V
L
SENSE
+
. On the other hand, the filter
, (Equation 13) is re−formulated
R
V
CONTROL(min)
CONTROL(min)
V
SENSE
R
CONTROL(min)
out
V
CS
M
out
L
V
. If the capacitors C
ac
V
is the one to filter the
I
ac
K
cs
L
BO
K
in
is proportional to the
L
BO
.
is roughly constant
) @ V
) @ V
I
L
REF
REF
SENSE
I
L*50
(eq. 13)
(eq. 14)
(eq. 11)
M
.
and
m
L
.