ncp1653 ON Semiconductor, ncp1653 Datasheet - Page 13

• Manufacturer Part Number: ncp1653
• Description: Compact Fixed-frequency Current-mode Power Factor Correction Controller
• Manufacturer: ON Semiconductor

becomes zero. The multiplier voltage V
becomes its maximum value and generates zero on time t
Then, V
a boost converter. Going down to V
enters the previous two regions (i.e., follower boost region
or constant output voltage region) and hence output voltage
V
provides a duty ratio for the operation of the boost
converter.
following conditions:
regulated around the range between 96% and 100% of R
× I
behavior is similar to a follower boost.
under 96% of R
100 mA. The output voltage is described in (eq.15).
Overvoltage Protection (OVP)
reference current I
Drive Output (Pin 7) of the device goes low for protection.
The circuit automatically resumes operation when the
feedback current becomes lower than 107% of the
reference current I
corresponds to 230 mA × 1.92 MW + 2.5 V = 444.1 V when
R
V
Hence, it is generally recommended to use 450 V rating
output capacitor to allow some design margin.
Undervoltage Protection (UVP)
reference current I
than 8% of its nominal value), the device is shut down and
consumes less than 50 mA. The device automatically starts
operation when the output voltage goes above 12% of the
nominal regulation level. In normal situation of boost
converter configuration, the output voltage V
greater than the input voltage V
out
FB
FB1
In conclusion, the NCP1653 circuit operates in one of the
Constant output voltage mode: The output voltage is
Follower boost mode: The output voltage is regulated
When the feedback current I
The maximum OVP threshold is limited to 230 mA which
When the feedback current I
I
I
CC2
stdn
I
ref
CC
cannot reach input voltage V
= 1.92 MW (680 kW + 680 kW + 560 kW) and
. The output voltage is described in (eq.16). Its
= 2.5 V (for the worst case referring to Figure 11).
out
Figure 35. Undervoltage Protection
decreases and the minimum can be V
8% I
FB
× I
ref
ref
ref
ref
Shutdown
.
ref
(i.e., V
(i.e., the output voltage V
and I
control
out
FB
in
FB
> 107% R
in
is higher than 107% of the
and the feedback current
12% I
as long as the NCP1653
is less than 8% of the
= I
in
, V
control(max)
ref
Operating
out
FB
automatically
M
out
× I
NCP1653, NCP1653A
out
out
in (eq.8)
is always
= I
ref
= V
http://onsemi.com
ref
is less
I
), the
FB
in
/2 =
FB
in
1
.
13
I
to enable the NCP1653 to operate. Hence, UVP happens
when the output voltage is abnormally undervoltage, the
FB pin (Pin 1) is opened, or the FB pin (Pin 1) is manually
pulled low.
Soft−Start
V
external capacitor C
provides a gradually increment of the V
the duty ratio) in the startup and hence provides a soft−start
feature.
Current Sense
sense scheme in Figure 36. The device maintains the
voltage at the CS pin (Pin 4) to be zero voltage (i.e.,
V
of components for current sensing and the inrush current
limitation by the resistor R
represents the inductor current I
PFC duty modulation to generate the multiplier voltage
V
protection.
Overcurrent Protection (OCP)
I
is typical 10 mV and it is neglected in the calculation.
Hence, the maximum OCP inductor current threshold
I
Drive Output (Pin 7) of the device goes low. The device
automatically resumes operation when the inductor current
goes below the threshold.
Input Voltage Sense
sensing scheme in Figure 37. The internal current mirror is
with a typical 4 V offset voltage at its input so that the
current I
FB
S(OCP)
L(OCP)
control
S
M
The device provides no output (or no duty ratio) when the
The device senses the inductor current I
This scheme has the advantage of the minimum number
Overcurrent protection is reached when I
When overcurrent protection threshold is reached, the
The device senses the RMS input voltage V
≈ 0 V) so that (eq.10) can be formulated.
, Overpower Limitation (OPL), and overcurrent
is always greater than 8% and 12% of the nominal level
I L(OCP) +
(200 mA typical). The offset voltage of the CS pin
is obtained in (eq.15).
R
(Pin 2) voltage is zero (i.e., V
vac
R
CS
S
can be derived in (eq.9). An external capacitor
Figure 36. Current Sensing
I
I
R S I S(OCP)
S
L
R CS
control
V
CS
+
−
S
I
L
CS
connected to the V
+
NCP1653
. Hence, the sense current I
R CS
R S
L
Gnd
and will be used in the
200 mA
control
control
L
S
by the current
is larger than
= 0 V). An
voltage (or
control
ac
(eq.18)
by the
pin
S