NCP1653A ON Semiconductor, NCP1653A Datasheet - Page 12

• Manufacturer Part Number: NCP1653A
• Description: Continuous Conduction Mode PFC Controller
• Manufacturer: ON Semiconductor

V
As a result, the on time t
makes the loss of the inductor and power MOSFET smaller.
Hence, it allows cheaper cost in the inductor and power
MOSFET or allows the circuit components to operate at a
lower stress condition in most of the time.
Output Feedback
feedback current I
device. Since the FB pin voltage V
V
(Pin 1) and the output voltage referring to Figure 2.
voltage V
regulation,
overvoltage protection (OVP).
Output Voltage Regulation
V
(I
function in Figure 32. The output of the voltage regulation
block, low−pass filter on V
V
And the input is feedback current I
is the output of I
There are three linear regions including: (1) I
I
discussed separately as follows:
Region (1): I
× I
regulation block output V
I
I
becomes (eq.15).
with a particular value of RMS input voltage V
ref
control
control(max)
V out + h
out
out
in
ref
control
The output voltage V
where R
Then, the feedback current I
Feedback current I
When I
The output voltage V
ref
, (2) 96% × I
even though V
, it is usually neglected.
), the NCP1653 operates in follower boost mode. The
is processed in a function with a reference current
= 200 mA typical) as shown in regulation block
T
/ R
I
becomes its maximum value (i.e., I
control(max)
FB
P out
V ac
out
2 R S R vac I control(max) V ref V ac
FB
1
= I
block is in Figure 30 is control current I
FB
is less than 96% of I
is the feedback resistor across the FB pin
undervoltage
Figure 32. Regulation Block
and will be used in the output voltage
ref
I FB +
< 96% × I
ref
FB
/2 = 100 mA) which is a constant. (eq.13)
out
FB
<I
and it can be described as in Figure 32.
FB
I
R M R CS P out
is reduced in follower boost operation.
flowing into the FB pin (Pin 1) of the
control
FB
V out * V FB1
96%
out
out
which represents the output voltage
1
< I
ref
is reduced. Reduction of on time
R FB
of the PFC circuit is sensed as a
is regulated at a particular level
ref
reg
I
ref
control
, and (3) I
protection
is at its maximum value.
FB
I
ref
ref
FB1
FB
[
pin and the I
represents the output
. It means that I
(i.e., V
is much smaller than
I
V out
R FB
FB
FB
> I
out
(UVP),
ac
ref
FB
< 96% R
NCP1653, NCP1653A
. They are
and output
< 96% ×
control
control
(eq.14)
(eq.15)
http://onsemi.com
control
control
and
FB
=
=
.
12
power P
depending on different values of V
boost operating area is illustrated in Figure 33.
Region (2): 96% × I
× I
output voltage mode which is similar to the follower boost
mode characteristic but with narrow output voltage range.
The regulation block output V
I
function of I
× I
of V
that output voltage increases when power decreases. It is
similar to the follower boost characteristic in (eq.15). On
the other hand in (eq.17), output voltage V
× I
maximum value of V
can also be concluded that output voltage increases when
RMS input voltage increases. It is similar to another
follower boost characteristic in (eq.15). This characteristic
is illustrated in Figure 34.
Region (3): I
NCP1653 provides no output or zero duty ratio. The
regulation block output V
96% I
FB
96% I
V out +
When I
Resolving (eq.16) and (eq.13),
According to (eq.17), output voltage V
When I
ref
ref
ref
in the range from 96% of I
out
< V
I
I control +
when power is low (P
ref
ref
ref
when RMS input voltage V
Figure 34. Constant Output Voltage Region
V out
in this operating region. Hence, it can be concluded
V out
out
R
V in
R
R
out
FB
FB
FB
FB
FB
2 R S R vac V ref
. However, this output level is not constant and
Figure 33. Follower Boost Region
< R
is between 96% and 100% of I
R M R CS
control
is greater than I
FB
FB
V
> I
V
I control(max)
ac(min)
ac(min)
× I
ref
in (eq.16).
P out(min)
ref
1
P out(min)
0.04
ref
1
out
I control(max)
< I
), the NCP1653 operates in constant
2
in this operating region. Hence, it
V ac
0.04
FB
2
out
V
reg
V
< I
ac(max)
ref
ac(max)
≈ 0). It is the maximum value
1. P
2. V
1. P
2. V
ref
1 *
becomes 0 V. I
reg
P out
(i.e., V
ref
P out(max)
h
out
ac
P out(max)
ac
out
ac
ac
decreases linearly with
to I
)
decreases, V
R FB I ref
increases, V
decreases, V
and P
increases, V
is very high. It is the
V out
V
R FB I ref
out
ref
V
ac
V ac
ac
. It gives a linear
> R
out
ref
out
out
. The follower
(i.e., 96% R
becomes R
becomes R
FB
out
out
out
out
control
× I
decreases
decreases
decreases
decreases
ref
(eq.16)
(eq.17)
), the
also
FB
FB
FB