NCP1631DR2G ON Semiconductor, NCP1631DR2G Datasheet - Page 17

• 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

Frequency Foldback
function to improve the light load efficiency. Practically,
the oscillator charge and discharge currents (I
I
the power level. More specifically, I
I
the regulation block that thanks to the feed−forward
featured by the NCP1631, is representative of the load.
function of V
increasing function of V
OSC(DISCH)
OSC(DISCH)
In addition, the circuit features the frequency fold−back
The practical implementation is portrayed by Figure 16.
The oscillator charge current is then an increasing function of V
The oscillator discharge current is:
The oscillator discharge current is also an increasing
As a consequence, the clamp frequency is also an
of Figure 16) are not constant but dependent on
linearly vary as a function of V
REGUL
Figure 17. Typical Waveforms (T
and is clamped to105 mA.
REGUL
until it reaches a maximum
control
OSC(CH)
OSC(CH)
I
I
I
I
OSC(CH)
OSC(CH)
OSC(DISCH)
OSC(DISCH)
output of
http://onsemi.com
delay
and
and
+ I
+ I
not shown here for the sake of simplicity)
+
+ I
OSC(clamp)
OSC(clamp)
17
V
OSC(DISCH1)
REGUL
R
effectively used to modulate the MOSFET on−time.
V
fold−back” pin). A resistor R
to sink a current proportional to V
This current is clamped not to exceed 105 mA and copied
by a current mirror to form I
value for (I
frequency f
value obtained at full load and if we name it “f
FF
REGUL
“V
As a matter of fact, the oscillator charge current is:
REGUL
REGUL
)
) I
V
OSC(CH1)
I
is buffered and applied to pin 6 (“Frequency
pin6
REGUL
R
and is clamped to 140 mA.
+ 105 mA
” is the signal derived from V
OSC
FF
FF
+ I
= 105 mA). If we consider the clamp
computed by Equation 17 as the nominal
FF
+ I
+
OSC(CHT1)
if
if
V
REGUL
R
V
V
FF
REGUL
REGUL
R
R
FF
FF
OSC(CH)
FF
+ 140 mA
.
is to be connected to pin 6
v 105 mA
v 105 mA
REGUL
and I
OSC(DISCH)
control
otherwise
otherwise
OSC(nom)
(eq. 18)
(eq. 19)
that is
.
”: