NCP1631DR2G ON Semiconductor, NCP1631DR2G Datasheet - Page 9

• Manufacturer Part Number: NCP1631DR2G
• Description: IC CTLR PFC INTERLEAVED 16SOIC
• Manufacturer: ON Semiconductor

Specifications of NCP1631DR2G

• Mode: Critical Conduction (CRM), Discontinuous Conduction (DCM)
• Frequency - Switching: 130kHz
• Current - Startup: 100µA
• Voltage - Supply: 10 V ~ 15 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

NCP1631 On−time Modulation
the interleaved PFC converter.
switching period (T
current as the result of the EMI filter “polishing” action.
Hence, the line current produced by one of the phase is:
Where (T
is the ac line rectified voltage.
Equation 1 shows that I
Forcing
constant is what the NCP1631 does to perform FCCrM
operation that is, to operate in discontinuous or critical
conduction mode according to the conditions, without
degradation of the power factor.
t
Let’s study the ac line current absorbed by one phase of
The current waveform of the inductor (L) during one
The ac line current is the averaged value of the coil
1
(t
T
1
) t
sw
2
sw
t
)
1
(t
Figure 5. Inductor Current in DCM
= t
1
T
is a constant.
sw
) t
1
Figure 4. Boost Converter
+ t
I
2
in
)
+ 1
sw
2
Figure 3. DCM and CRM Operation Within a Sinusoid Cycle for One Branch
+ t
) is portrayed by Figure 5.
2
3
in
) is the switching period and V
t
L
1
is proportional to V
t
1
T
) t
sw
2
V
in
in
if
http://onsemi.com
(eq. 1)
in
9
Figure 6, the MOSFET on time t
V
Where:
•
•
placed on the R
condition
to be a constant for proper power factor correction can be
changed into:
linearly changed into a signal (V
0 and 1.66 V. (V
the PWM section to modulate the MOSFET duty−cycle.
However, the NCP1631 inserts some circuitry that
processes (V
in the PWM section instead of (V
(V
during the precedent current cycles, that is, for a proper
shaping of the ac line current. This modulation leads to:
V
following on−time expression:
Equation 1 simplifies as follows:
TON
ton
The NCP1631 operates in voltage mode. As portrayed by
The I
The output of the regulation block (V
Substitution of Equation 3 into Equation 2 leads to the
Replacing “t
C
I
TON
t
V
t
is the internal current source for the timing capacitor.
TON
generated by the regulation block as follows:
is the internal timing capacitor
+
) is modulated in response to the dead−time sensed
t
T
(t
T
charge current is constant for a given resistor
sw
1
sw
I
in(phase1)
t
) t
1
V
REGUL
) t
REGUL
2
)
1
REGUL
2
t
” by its expression of Equation 4,
t
pin. C
1
is constant.
) to form the signal (V
+ I
+
t
or:
) is the voltage that is injected into
C
in(phase2)
1
t
1
+
t
t
(t
is also a constant. Hence, the
T
1
T
V
C
sw
sw
) t
TON
t
t
V
1
V
I
I
TON
)t
1
t
t
+
2
REGUL
t
)
is controlled by the signal
REGUL
1
T
2
V
REGUL
) t
2L
sw
in
C
2
t
) varying between
+ V
V
TON
) (see Figure 7).
REGUL
I
t
REGUL
CONTROL
) that is used
(eq. 2)
(eq. 3)
(eq. 4)
(eq. 5)
) is