NCP1631DR2G ON Semiconductor, NCP1631DR2G Datasheet - Page 18

• 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

1.66 V, (V
power (P
stage as selected by the timing resistor (for more details,
you can refer to the application note AND8407).
properly with a constant 140 mA oscillator charge current and
a 105 mA discharge current. The clamp frequency equates its
nominal value over the whole load range.
I
hence the PFC stage cannot operate.
clamp frequency can be forced by placing a resistor
between pin 4 and ground. For instance, a 1.5−MW resistor
forces a 3.3−mA discharge current when the oscillator
capacitor is fully charged and about 2.6 mA when it is near
the oscillator low threshold (4 V).
OSC(clamp)
Let’s illustrate this operation on an example.
V
For instance, if the nominal frequency (f
If pin6 is grounded (accidently or not), the circuit operates
If pin6 is open, the oscillator charge current is equal to
A minimum discharge current and hence a minimum
REGUL
Figure 18. Fold−back Characteristic of the Clamp Frequency with R
in
REGUL
)
is the control signal that varies between 0 and
HL
but the oscillator discharge current is null and
that can virtually be delivered by the PFC
= 1.66 V) corresponding to the maximum
f
f
f
f
OSC
OSC
OSC
OSC
150
100
+ f
+
+ f
+
50
0
60 m R
V
492 m(R
0
OSC(nom)
OSC(nom)
V
REGUL
REGUL
FF
(R
FF
(R
(R
FF
OSC(nom)
I
FF
FF
OSC(clamp)
I
OSC(clamp)
I
I
OSC(clamp)
OSC(clamp)
0.5
http://onsemi.com
) is 120 kHz, the following characteristic is obtained.
) 2V
) V
V
) V
) 2V
REGUL
18
REGUL
REGUL
REGUL
REGUL
(V)
when the power goes below (P
current should start to decrease when V
pin 6 sources 105 mA when V
This selection leads to:
the frequency fold−back function.
Skip Mode
a very efficient stand−by mode. In order to ensure a proper
regulation in no load conditions even if this feature is not
used (pin 6 grounded), the circuit skips cycles when the
error amplifier output is at its minimum level. The error
amplifier output is maintained between about 0.6 V and
3.6 V thanks to active clamps. A skip sequence occurs as
long as the 0.6 V clamp circuitry is triggered and switching
operation is recovered when the clamp is inactive.
If one decides to start to reduce the clamp frequency
Hence, the pin 6 resistor (“R
Let’s take (R
)
)
A transistor pulls the pin 6 down during startup to disable
The circuit features the frequency fold−back that leads to
)
@ f
)
1
@ f
OSC(nom)
f
OSC(nom)
if V
OSC(nom)
REGUL
FF
FF
= 8.2 kW and f
R
= 120 kHz
= 8.2 kW) which is a normalized value.
FF
if V
if V
w 8.2 k @ 105 m + 860 mV
if V
+
1.5
REGUL
REGUL
REGUL
105 mA
0.83 V
w R
v R
v 860 mV
in
REGUL
FF
OSC(nom)
)
+ 7.9 kW
HL
”) must be selected so that
FF
FF
/2, the oscillator charge
@ 105 mA
@ 105 mA
equates 0.83 V:
REGUL
= 120 kHz
is 0.83 V.
(eq. 20)
(eq. 22)
(eq. 21)