NCP1651DR2G ON Semiconductor, NCP1651DR2G Datasheet - Page 17

• Manufacturer Part Number: NCP1651DR2G
• Description: IC PFC CONTROLLER CCM/DCM 16SOIC
• Manufacturer: ON Semiconductor

Specifications of NCP1651DR2G

• Mode: Continuous Conduction (CCM), Discontinuous Conduction (DCM)
• Frequency - Switching: 250kHz
• Current - Startup: 8.5mA
• Voltage - Supply: 10 V ~ 18 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (3.9mm Width)
• Switching Frequency: 25 KHz to 250 KHz
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: NCP1651DR2GOS; NCP1651DR2GOS; NCP1651DR2GOSTR

into a high quality sine wave is the operation of the AC error
amplifier. The inputs of an operational amplifier operating
in its linear range, must be equal. There are several
secondary effects, that create small differences between the
inverting and non- -inverting inputs, but for the purpose of
this analysis they can be considered to be equal.
multiplier is fed into the non- -inverting input of the AC error
amplifier. The inverting input to the AC error amplifier
receives a signal that is comprised of the input fullwave
rectified sinewave (which is not modified by the reference
multiplier), and summed with the filtered input current.
Since the two inputs to this amplifier will be at the same
potential, the complex signal at the non- -inverting input will
have the same waveshape as the AC reference signal. The
AC reference signal (V
and the AC input signal (V
sinewave, therefore, the AC current signal (I
a fullwave rectified sinewave. This relationship gives the
formula:
value will not follow the low frequency fullwave rectified
sinewave exactly, however, the output of the AC error
amplifier has a low frequency pole that allows the average
value of the .75 V
error amplifier is a transconductance amplifier, it is followed
by an inverting unity gain buffer stage with a low impedance
output so that the signal can be summed with the
instantaneous input switching current (I
buffer is still V
reference, sets the window that the instantaneous current
will modulate in, to determine when to turn the power switch
off.
is twice that of the line, the output filter must have poles
The key to understanding how the input current is shaped
The fullwave rectified sinewave output of the reference
The Iin signal has a wide bandwidth, and its instantaneous
The difference between V
Since the input current has a fundamental frequency that
V ref = .75 ⋅ V ref + (k × I in )
error(ac)
line
+ (k x I
.
ref
) is a fullwave rectified sinewave,
line
in
) to follow V
) is also a fullwave rectified
error(ac)
in
and the 4.0 volt
). The output of the
ref
in
. Since the AC
), must also be
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17
lower than the input current to create a reasonable DC
waveform. The DC output voltage is compared to a
reference voltage by a secondary side error amplifier, and
the error signal out of the secondary side amplifier is fed
back into the Feedback input through an optocoupler.
a fixed frequency controller. Under normal operation, the
switch will remain on until the instantaneous value of
V
the switch will turn off.
.75  V
error(ac)
The switch is turned on by the oscillator, which makes this
AC Input
V
V
line
error(ac)
error(ac)
Figure 31. Typical Signals for PFC Circuit
 reaches the 4.0 volt reference level, at which time
k  I
V
+ k  I
V
line
ref
in
in
V
error(ac)
V
ref
OSC
4 V ref
GND
4 V ref
GND