NCP1632ADR2G [ONSEMI]

Critical Conduction Mode (CrM) Power Factor Controller, Interleaved;
NCP1632ADR2G
型号: NCP1632ADR2G
厂家: ONSEMI    ONSEMI
描述:

Critical Conduction Mode (CrM) Power Factor Controller, Interleaved

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中文:  中文翻译
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DATA SHEET  
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2-Phase Power Factor  
Controller, Interleaved  
SOIC16  
D SUFFIX  
CASE 751B  
NCP1632A  
The NCP1632A integrates a dual MOSFET driver for interleaved  
PFC applications. Interleaving consists of paralleling two small stages  
in lieu of a bigger one, more difficult to design. This approach has  
several merits like the ease of implementation, the use of smaller  
components or a better distribution of the heating.  
MARKING DIAGRAM  
NCP1632AG  
AWLYWW  
Also, Interleaving extends the power range of Critical Conduction  
Mode that is an efficient and costeffective technique (no need for low  
t diodes). In addition, the NCP1632A drivers are 180° phase shifted  
rr  
NCP1632AG = Device Code  
for a significantly reduced current ripple.  
A
WL  
Y
= Assembly Location  
= Wafer Lot  
= Year  
Housed in a SOIC16 package, the circuit incorporates all the  
features necessary for building robust and compact interleaved PFC  
stages, with a minimum of external components.  
WW  
G
= Work Week  
= PbFree Package  
General Features  
NearUnity Power Factor  
Substantial 180° Phase Shift in All Conditions Including Transient  
Phases  
PIN ASSIGNMENT  
ZCD2  
FB  
ZCD1  
Frequency Clamped Critical Conduction Mode (FCCrM) i.e., Fixed  
Frequency, Discontinuous Conduction Mode Operation with Critical  
Conduction Achievable in Most Stressful Conditions  
FCCrM Operation Optimizes the PFC Stage Efficiency Over the  
Load Range  
Outofphase Control for Low EMI and a Reduced rms Current in  
the Bulk Capacitor  
Frequency Foldback at Low Power to Further Improve the Light  
Load Efficiency  
1
REF5V/pfcOK  
DRV1  
Rt  
OSC  
GND  
Vcc  
Vcontrol  
FFOLD  
DRV2  
BO  
Latch  
CS  
OVP / UVP  
(Top View)  
Accurate Zero Current Detection by Auxiliary Winding for Valley  
Turn On  
Fast Line / Load Transient Compensation  
ORDERING INFORMATION  
High Drive Capability: 500 mA / +800 mA  
Device  
NCP1632ADR2G  
Package  
Shipping  
Signal to Indicate that the PFC is Ready for Operation (“pfcOK” Pin)  
SOIC16  
(PbFree)  
2500 / Tape &  
Reel  
V Range: from 10 V to 20 V  
CC  
Safety Features  
†For information on tape and reel specifications,  
including part orientation and tape sizes, please  
refer to our Tape and Reel Packaging Specifications  
Brochure, BRD8011/D.  
Output Over and Under Voltage Protection  
BrownOut Detection with a 50ms Delay to Help Meet Holdup  
Time Specifications  
SoftStart for Smooth Startup Operation  
Programmable Adjustment of the Maximum Power  
Over Current Limitation  
Typical Applications  
Computer Power Supplies  
LCD / Plasma Flat Panels  
Detection of Inrush Currents  
All Off Line Appliances Requiring Power  
Factor Correction  
© Semiconductor Components Industries, LLC, 2022  
1
Publication Order Number:  
June, 2022 Rev. 1  
NCP1632A/D  
NCP1632A  
VIN  
VOUT  
Dbypass  
L2  
RBO1  
VOUT  
V
AUX2  
pfcOK  
ROUT1  
ROUT2  
RBO2  
ROVP1  
L1  
V
AUX2  
RZCD2  
ZCD2  
RZCD1  
CpfcOK  
ZCD1  
pfcOK  
DRV1  
D1  
1
16  
15  
14  
13  
12  
11  
10  
9
ROUT3  
FB  
ROVP2  
2
RT  
Rt  
3
D2  
M1  
ROSC  
CFF  
OSC  
GND  
VCC  
OVP  
4
in  
COSC  
CVCC  
Vcontrol  
M2  
5
CCOMP2  
RCOMP1  
RFOLD  
Ac line  
DRV2  
FFOLD  
RBO3 ROVP3  
6
Latch  
CS  
BO  
CFOLD  
7
OVP/UVP  
EMI  
Filter  
CCOMP1  
8
CBO2  
CBULK  
CIN  
ROCP  
OVPin  
RCS  
Figure 1. Typical Application Schematic  
Table 1. MAXIMUM RATINGS  
Symbol  
Rating  
Pin  
Value  
Unit  
V
Maximum Power Supply Voltage Continuous  
12  
0.3, +20  
0.3, +9.0  
V
V
CC(MAX)  
V
MAX  
Maximum Input Voltage on Low Power Pins (Note 1)  
1, 2, 3, 4, 6, 7, 8,  
9, 10, 15, and 16  
V
V
Control  
Pin Maximum Input Voltage  
5
0.3, V  
(Note 2)  
V
Control(MAX)  
Control(clamp)  
Power Dissipation and Thermal Characteristics  
P
Maximum Power Dissipation @ T = 70°C  
550  
145  
mW  
°C/W  
D
A
R
Thermal Resistance JunctiontoAir  
Operating Junction Temperature Range  
Maximum Junction Temperature  
q
JA  
T
40 to +150  
°C  
°C  
°C  
°C  
kV  
V
J
T
150  
65 to +150  
300  
J(MAX)  
S(MAX)  
T
Storage Temperature Range  
T
Lead Temperature (Soldering, 10 s)  
ESD Capability, HBM model (Note 3)  
ESD Capability, Machine Model (Note 3)  
ESD Capability, Charged Device Model (Note 3)  
L(MAX)  
3
200  
1000  
V
Stresses exceeding those listed in the Maximum Ratings table may damage the device. If any of these limits are exceeded, device functionality  
should not be assumed, damage may occur and reliability may be affected.  
1. These maximum ratings (0.3 V / 9.0 V) guarantee that the internal ESD Zener diode is not turned on. More positive and negative voltages  
can be applied to the ZCD1 pin if the ESD Zener diode current is limited to 5 mA maximum. Typically, as detailed in the Zero Current Detection  
section, an external resistor is to be placed between the ZCD1 pin and its driving voltage to limit the ZCD1 source and sink currents to 5 mA  
or less. See Figure 2 and application note AND9654 for more details. The same is valid for the ZCD2 pin.  
2. “V ” is the pin5 clamp voltage.  
Control(clamp)  
3. This device(s) contains ESD protection and exceeds the following tests:  
Human Body Model 2000 V per JEDEC Standard JESD22A114E  
Machine Model Method 200 V per JEDEC Standard JESD22A115A  
Charged Device Model Method 1000 V per JEDEC Standard JESD22C101E  
4. This device contains latchup protection and exceeds 100 mA per JEDEC Standard JESD78F.  
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2
 
NCP1632A  
ZCD1 pin  
RZCD1  
IZCD1  
ESD  
Zener  
Diode  
V
ZCD1  
Circuitry  
AUX1  
GND  
NCP1632A  
Figure 2. Limit the ZCD1 Pin Current (IZCD1) between – 5 mA and 5 mA (the Same is Valid for the ZCD2 Pin)  
Table 2. TYPICAL ELECTRICAL CHARACTERISTICS TABLE  
(Conditions: V = 15 V, V  
= 2 V, V = 0 V, T from 40°C, to +125°C, unless otherwise specified)  
pin10 J  
CC  
pin7  
Characteristics  
Test Conditions  
Symbol  
Min  
Typ  
Max  
Unit  
STARTUP AND SUPPLY CIRCUITS  
Supply Voltage  
V
Startup Threshold  
Minimum Operating Voltage  
V
V
increasing  
decreasing  
V
V
11  
12  
10  
2.0  
6.0  
13  
10.4  
CC  
CC(on)  
9.4  
1.5  
4.0  
CC  
CC(off)  
Hysteresis V  
– V  
V
V
CC(on)  
CC(off)  
CC(hyst)  
CC(reset)  
Internal Logic Reset  
V
V
decreasing  
= 9.4 V  
7.5  
CC  
Startup Current  
I
50  
100  
mA  
CC  
CC(start)  
Supply Current  
mA  
Device Enabled/No Output Load on Pin6  
Current that Discharges V in Latch Mode  
F
= 130 kHz (Note 5)  
I
3.5  
0.4  
0.4  
7.0  
0.8  
0.8  
2.6  
sw  
CC1  
V
V
V
= 15 V, V  
= 5 V  
I
CC(latch)  
I
CC(off)  
CC  
CC  
CC  
FB  
pin10  
Current that Discharges V in OFF Mode  
= 15 V, pin 7 grounded  
= 3 V  
CC  
SKIP Mode Consumption  
I
CC(SKIP)  
OSCILLATOR AND FREQUENCY FOLDBACK  
Charge Current  
Pin 6 open  
Pin 6 open  
I
120  
90  
140  
105  
1
154  
115  
mA  
mA  
-
CH  
Maximum Discharge Current  
I
DISCH  
I
over I Ratio  
I
I
= 30 mA  
= 30 mA  
R
FFOLD  
CS  
CS  
CS  
FFOLD30  
FFOLD30  
Pin 6 Source Current  
I
28  
30  
5
32  
mA  
V
Oscillator Upper Threshold  
Oscillator Lower Threshold  
V
OSC(high)  
V
FFOLD  
V
FFOLD  
V
FFOLD  
V
FFOLD  
V
FFOLD  
= 4.2 V, V  
falling  
falling  
rising  
falling  
falling  
V
OSC(low)  
3.6  
3.6  
2.7  
1.8  
0.8  
4.0  
4.0  
3.0  
2.0  
1.0  
4.4  
4.4  
3.3  
2.2  
1.1  
V
FFOLD  
FFOLD  
FFOLD  
FFOLD  
FFOLD  
= 3.8 V, V  
= 3.8 V, V  
= 2.0 V, V  
= 0.8 V, V  
Oscillator Swing (Note 6)  
V
FFOLD  
V
FFOLD  
V
FFOLD  
V
FFOLD  
V
FFOLD  
= 4.2 V, V  
= 3.8 V, V  
= 3.8 V, V  
= 2.0 V, V  
= 0.8 V, V  
falling  
falling  
rising  
falling  
falling  
V
OSC(swing)  
0.90  
0.90  
1.90  
2.85  
3.80  
1.00  
1.00  
2.00  
3.00  
4.00  
1.05  
1.05  
2.10  
3.15  
4.20  
V
FFOLD  
FFOLD  
FFOLD  
FFOLD  
FFOLD  
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NCP1632A  
Table 2. TYPICAL ELECTRICAL CHARACTERISTICS TABLE (continued)  
(Conditions: V = 15 V, V  
= 2 V, V = 0 V, T from 40°C, to +125°C, unless otherwise specified)  
pin10 J  
CC  
pin7  
Characteristics  
CURRENT SENSE  
Test Conditions  
Symbol  
Min  
Typ  
Max  
Unit  
Current Sense Voltage Offset  
I
I
= 100 mA  
= 10 mA  
V
V
20  
10  
0
0
20  
10  
mV  
mA  
mA  
pin9  
CS(TH100)  
CS(TH10)  
pin9  
Current Sense Protection Threshold  
T = 25°C  
T = 40°C to 125°C  
I
I
199  
190  
210  
210  
228  
228  
J
ILIM1  
J
ILIM2  
Threshold for Inrush Current Detection  
GATE DRIVE (Note 8)  
I
11  
14  
17  
inrush  
Drive Resistance  
DRV1 Sink  
DRV1 Source  
DRV2 Sink  
W
I
I
I
I
= 100 mA  
= 100 mA  
= 100 mA  
= 100 mA  
R
SNK1  
R
SRC1  
R
SNK2  
R
SRC2  
7
15  
7
15  
25  
15  
25  
pin14  
pin14  
pin11  
pin11  
DRV2 Source  
15  
Drive Current Capability (Note 6)  
DRV1 Sink  
DRV1 Source  
DRV2 Sink  
DRV2 Source  
mA  
V
DRV1  
V
DRV1  
V
DRV2  
V
DRV2  
= 10 V  
= 0 V  
= 10 V  
= 0 V  
I
800  
500  
800  
500  
SNK1  
I
SRC1  
I
I
SNK2  
SRC2  
Rise Time  
DRV1  
DRV2  
ns  
ns  
C
C
= 1 nF, V  
= 1 nF, V  
= 1 to 10 V  
= 1 to 10 V  
t
t
40  
40  
DRV1  
DRV1  
r1  
DRV2  
DRV2  
r2  
Fall Time  
DRV1  
DRV2  
C
C
= 1 nF, V  
= 1 nF, V  
= 10 to 1 V  
= 10 to 1 V  
t
t
20  
20  
DRV1  
DRV1  
f1  
DRV2  
DRV2  
f2  
REGULATION BLOCK  
Feedback Voltage Reference  
Error Amplifier Source Current Capability  
Error Amplifier Sink Current Capability  
Error Amplifier Gain  
V
2.44  
2.50  
20  
+20  
200  
2.56  
V
REF  
@ V  
@ V  
= 2.4 V  
= 2.6 V  
I
mA  
pin2  
EA(SRC)  
I
pin2  
EA(SNK)  
G
115  
285  
mS  
mA  
EA  
Control(boost)  
Pin 5 Source Current when (V  
Activated  
Detect) is  
pfcOK high  
pfcOK low  
I
175  
55  
220  
70  
265  
85  
out(low)  
Pin2 Bias Current  
Pin 5 Voltage  
V
= 2.5 V  
I
500  
500  
nA  
V
pin2  
FB(bias)  
@ V  
@ V  
= 2.4 V  
V
V
2.8  
3.6  
0.6  
3.0  
3.5  
pin2  
Control(clamp)  
= 2.6 V  
V
pin2  
Control(MIN)  
Control(range)  
Ratio (V  
Ratio (V  
Detect Threshold / V  
) (Note 6) FB falling  
V /V  
out(low) REF  
95.0  
95.5  
96.0  
0.5  
%
%
out(low)  
REF  
Detect Hysteresis / V  
) (Note 6) FB rising  
REF  
H
/V  
out(low)  
out(low) REF  
SKIP MODE  
Duty Cycle  
V
FB  
= 3 V  
D
MIN  
0
%
RAMP CONTROL (VALID FOR THE TWO PHASES)  
Maximum DRV1 and DRV2 OnTime  
(FB Pin Grounded)  
V
= 1.1 V, I  
= 1.1 V, I  
= 2.2 V, I  
= 2.2 V, I  
= 50 mA (Note 6)  
= 200 mA  
= 100 mA  
t
t
t
t
14.5  
1.00  
3.80  
0.34  
19.5  
1.35  
5.00  
0.41  
22.5  
1.60  
6.00  
0.50  
ms  
pin7  
pin7  
pin7  
pin7  
pin3  
pin3  
pin3  
pin3  
on1  
on2  
on3  
on4  
V
V
V
= 400 mA  
Pin 3 Voltage  
V
BO  
V
BO  
V
BO  
V
BO  
= V  
= V  
= V  
= V  
= 1.1 V, I  
= 1.1 V, I  
= 2.2 V, I  
= 2.2 V, I  
= 50 mA  
= 200 mA  
= 50 mA  
= 200 mA  
V
Rt1  
V
Rt2  
V
Rt3  
V
Rt4  
1.068 1.096 1.126  
1.068 1.096 1.126  
2.165 2.196 2.228  
2.165 2.196 2.228  
V
pin7  
pin7  
pin7  
pin7  
pin3  
pin3  
pin3  
pin3  
Maximum V Voltage  
Not tested  
V
5
V
ton  
ton(MAX)  
Rt(MAX)  
Pin 3 Current Capability  
I
1
mA  
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4
NCP1632A  
Table 2. TYPICAL ELECTRICAL CHARACTERISTICS TABLE (continued)  
(Conditions: V = 15 V, V  
= 2 V, V = 0 V, T from 40°C, to +125°C, unless otherwise specified)  
pin10 J  
CC  
pin7  
Characteristics  
Test Conditions  
Symbol  
Min  
Typ  
Max  
Unit  
RAMP CONTROL (VALID FOR THE TWO PHASES)  
Pin 3 Sourced Current Below which the  
Controller is OFF  
I
7
mA  
mA  
Rt(off)  
Pin 3 Current Range  
(Note 6)  
I
20  
1000  
Rt(range)  
ZERO VOLTAGE DETECTION CIRCUIT (VALID FOR ZCD1 AND ZCD2)  
ZCD Threshold Voltage  
ZCD Hysteresis  
V
V
increasing  
falling  
V
V
0.40  
0.20  
0.50  
0.25  
0.60  
0.30  
V
ZCD  
ZCD(TH),H  
ZCD  
ZCD(TH),L  
V
ZCD  
decreasing  
V
0.25  
V
V
ZCD(HYS)  
Input Clamp Voltage  
High State  
Low State  
I
I
= 5.0 mA  
= 5.0 mA  
V
V
9.0  
11  
13  
pin1  
ZCD(high)  
1.10 0.65 0.10  
pin1  
ZCD(low)  
Internal Input Capacitance (Note 6)  
ZCD Watchdog Delay  
C
10  
pF  
ZCD  
t
80  
200  
320  
ms  
ZCD  
BROWNOUT DETECTION  
BrownOut Comparator Threshold  
BrownOut Current Source  
V
0.97  
6
1.00  
7
1.03  
8
V
BO(TH)  
I
mA  
ms  
ms  
mV  
BO  
BrownOut Blanking Time (Note 6)  
BrownOut Monitoring Window (Note 6)  
t
38  
38  
50  
62  
62  
BO(BLANK)  
BO(window)  
t
50  
Pin 7 Clamped Voltage if V < V  
BO(BLANK)  
During  
I
I
I
= 100 mA  
= 100 mA  
= 100 mA  
V
965  
BO  
BO(TH)  
pin7  
pin7  
pin7  
BO(clamp)  
t
Current Capability of the BO Clamp  
Hysteresis V – V  
I
100  
10  
35  
60  
mA  
mV  
mA  
BO(clamp)  
V
BO(TH)  
BO(clamp)  
BO(HYS)  
Current Capability of the BO pin Clamp PNP  
Transistor  
I
100  
BO(PNP)  
Pin BO Voltage when Clamped by the PNP  
OVER AND UNDER VOLTAGE PROTECTIONS  
OverVoltage Protection Threshold  
V
0.35  
0.70  
0.90  
V
BO(PNP)  
V
2.425 2.500 2.575  
V
%
OVP  
Ratio (V  
/ V ) (Note 6)  
REF  
V
/V  
OVP REF  
99.2  
8
99.7  
12  
100.2  
16  
OVP  
Ratio UVP Threshold over V  
Pin 8 Bias Current  
V
/V  
UVP REF  
%
REF  
V
V
= 2.5 V, V  
= 0.3 V  
I
OVP(bias)  
500  
500  
nA  
pin8  
pin8  
LATCH INPUT  
Pin Latch Threshold for Shutdown  
Pin Latch Bias Current  
V
2.3  
2.5  
2.7  
V
Latch  
= 2.5 V  
I
500  
500  
nA  
pin10  
Latch(bias)  
pfcOK / REF5V  
Pin 15 Voltage Low State  
Pin 15 Voltage High State  
Current Capability  
V
V
= 0 V, I  
= 0 V, I  
= 250 mA  
V
4.7  
5
60  
5.0  
10  
120  
5.3  
mV  
V
pin7  
pin15  
REF5V(low)  
= 5 mA  
V
pin7  
pin15  
REF5V(high)  
I
mA  
REF5V  
THERMAL SHUTDOWN  
Thermal Shutdown Threshold  
Thermal Shutdown Hysteresis  
(Note 6)  
T
130  
140  
50  
150  
°C  
°C  
SHDN  
T
SHDN(HYS)  
Product parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Product  
performance may not be indicated by the Electrical Characteristics if operated under different conditions.  
5. DRV1 and DRV2 pulsating at half this frequency, that is, 65 kHz.  
6. Not tested. Guaranteed by design.  
7. Not tested. Guaranteed by design and characterization.  
8. Guaranteed by design, the VCC pin can handle the double of the DRV peak source current, that is, 1 A typically.  
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5
 
NCP1632A  
Table 3. DETAILED PIN DESCRIPTION  
Pin number  
Name  
Function  
1
ZCD2  
This is the zero current detection pin for phase 2 of the interleaved PFC stage. It is designed to  
monitor the voltage of an auxiliary winding to detect the inductor core reset and the valley of the  
MOSFET drain source voltage  
2
FB  
This pin receives the portion of the PFC stage output voltage for regulation. V is also monitored by  
FB  
the dynamic response enhancer (DRE) which drastically speedsup the loop response when the  
output voltage drops below 95.5 % of the wished level.  
3
4
5
R
The resistor placed between pin 3 and ground adjusts the maximum ontime in both phases, and  
T
hence the maximum power that can be delivered by the PFC stage.  
OSC  
Oscillator pin. The oscillator sets the maximum switching frequency, particularly in mediumand  
lightload conditions when frequency foldback is engaged.  
V
The error amplifier output is available on this pin for loop compensation. The capacitors and resistor  
connected between this pin and ground adjusts the regulation loop bandwidth that is typically set  
below 20 Hz to achieve high Power Factor ratios. Pin5 is grounded when the circuit is off so that  
when it starts operation, the power increases gradually (softstart).  
CONTROL  
6
7
FFOLD  
This pin sources a current proportional to the input current. Placing a resistor and a capacitor  
(Freq. Foldback) between the FFOLD pin and GND, we obtain the voltage representative of the line current  
magnitude necessary to control the frequency foldback characteristics.  
BO  
(Brownout  
Protection)  
Apply an averaged portion of the input voltage to detect brownout conditions when V drops  
BO  
below 1 V. A 50ms internal delay blanks short mains interruptions to help meet holdup time  
requirements. When it detects a brownout condition, the circuit stops pulsing and grounds the  
“pfcOK” pin to disable the downstream converter. Also an internal 7mA current source is activated  
to offer a programmable hysteresis.  
The pin2 voltage is internally reused for feedforward.  
Ground pin 2 to disable the part.  
8
9
OVP / UVP  
CS  
The circuit turns off when V  
goes below V  
(300 mV typically – UVP protection) and disables  
pin8  
UVP  
the drive when the pin voltage exceeds V  
(2.5 V typically OVP protection).  
OVP  
The CS pin monitors a negative voltage proportional to the input current to limit the maximum  
(Current Sense) current flowing in the phases. The NCP1632A also uses the CS information to prevent the PFC  
stage from starting operation in presence of large inrush currents.  
10  
Latch  
DRV2  
Apply a voltage higher than V  
(2.5 V typically) to latchoff the circuit. The device is reset by  
STDWN  
unplugging the PFC stage (practically when the circuit detects a brownout detection) or by forcing  
the circuit V below V RST (4 V typically). Operation can then resume when the line is applied  
CC  
CC  
back.  
11  
12  
This is the gate drive pin for phase 2 of the interleaved PFC stage. The highcurrent capability of  
the totem pole gate drive (+0.5/0.8A) makes it suitable to effectively drive high gate charge power  
MOSFETs.  
V
CC  
This pin is the positive supply of the IC. The circuit starts to operate when V exceeds 12 V and  
CC  
turns off when V goes below 10 V (typical values). After startup, the operating range is 10.5 V  
CC  
up to 20 V.  
13  
14  
GND  
Connect this pin to the preconverter ground.  
DRV1  
This is the gate drive pin for phase 1 of the interleaved PFC stage. The highcurrent capability of  
the totem pole gate drive (+0.5/0.8A) makes it suitable to effectively drive high gate charge power  
MOSFETs.  
15  
16  
REF5V / pfcOK  
ZCD1  
The pin15 voltage is high (5 V typically) when the PFC stage is in a normal, steady state situation  
and low otherwise. This signal serves to “inform” the downstream converter that the PFC stage is  
ready and that hence, it can start operation.  
This is the zero current detection pin for phase 1 of the interleaved PFC stage. It is designed to  
monitor the voltage of an auxiliary winding to detect the inductor core reset and the valley of the  
MOSFET drain source voltage.  
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6
NCP1632A  
DRE  
pfcOK  
150 mA  
COMP  
Vref  
VDD  
Iref  
Internal  
Thermal  
Shutdown  
0.955*V  
ref  
+
Vcc  
50 mA  
Regul  
TSD  
VDD  
Stdwn  
UVP  
FB  
Error Amplifier  
Vcc_OK  
+/20 mA  
BO_NOK  
+
V
ref  
V
CC(on)  
/ V  
Vcontrol  
CC(off)  
UVLO  
OFF  
Fault  
management  
SKIP  
OVLflag1  
BO_NOK  
V
OPAMP  
OFF  
4R  
BO  
OCP  
V
Brownout detection  
with 50ms delay  
REGUL  
STOP  
V
3V  
5R  
BO  
OVP  
OFF  
V
OSC(low)  
SKIP  
CLK2  
Vcc  
Output  
Buffer 2  
DRV2  
S
Oscillator low  
threshold  
control  
Vpwm2  
Freq foldback  
DT  
Vton  
Q
L
R
processing  
circuitry  
pwm2  
V
OPAMP  
STOP  
V
Vton  
BO  
DRV1  
DRV2  
CLK1  
Vcc  
Output  
Buffer 1  
DRV1  
Generation of the  
charge current for the  
Internal timing  
S
Rt  
Vpwm1  
I
Q
Vpwm1  
Vpwm2  
ch  
Ontime control  
for the two phases  
L
R
pwm1  
capacitors  
(max ontime setting for  
the twophases)  
STOP  
Inrush  
CLK1  
V
Oscillator block  
with interleaving and  
frequency foldback  
Inrush  
DMG2  
OSC  
CLK2  
V
ZCD1  
Zero  
current  
ZCD2  
V
V
V
ZCD2  
All the RS latches are  
RESET dominant  
OSC(low)  
detection  
for phase 2  
ZCD1  
OUTon2  
REF5V  
V
DMG1  
V
pfcOK  
ZCD1  
pfcOK / REF5V  
OFF  
Stup  
Zero  
current  
ZCD1  
DT  
OFF  
S
R
detection  
for phase 1  
Q
OUTon1  
Lstup  
OVLflag1  
Current Sense Block  
OVP  
UVP  
(Building of I  
CS  
proportional to I  
)
in  
+
V
UVP  
OCP  
Ics > I  
ILIM1  
Ics  
+
OVP  
CS  
V
Inrush  
OVP  
+
Ics > I  
inrush  
Vcc < VccRST  
Q
R
zcd1  
stdwn  
Q
Q
V
zcd2  
DRV  
GND  
STDWN  
Lstdwn  
S
latchoff  
1
+
DRV  
2
Figure 3. Block Diagram  
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7
NCP1632A  
DETAILED OPERATING DESCRIPTION  
Introduction  
Output Stage Totem Pole: the NCP1632A incorporates  
a 0.5 A / +0.8 A gate driver to efficiently drive most  
TO220 or TO247 power MOSFETs.  
Safety Protections: the NCP1632A permanently  
monitors the input and output voltages, the inductor  
current and the die temperature to protect the system from  
possible overstresses and make the PFC stage extremely  
robust and reliable. In addition to the aforementioned  
OVP protection, one can list:  
The NCP1632A is an interleaving, 2phase PFC  
controller. It is designed to operate in critical conduction  
mode (CrM) in heavy load conditions and in discontinuous  
conduction mode (DCM) with frequency foldback in light  
load for an optimized efficiency over the whole power  
range. In addition, the circuit incorporates protection  
features for a rugged operation. More generally, the  
NCP1632A functions make it the ideal candidate in systems  
where costeffectiveness, reliability, low standby power,  
highlevel efficiency over the load range and nearunity  
power factor are the key parameters:  
Accurate and robust interleaving management:  
The NCP1632A modulates the oscillator swing as a  
function of the current cycle duration to control the delay  
between the two branches drive pulses. This ON  
proprietary method is a simple but robust and stable  
solution to interleave the two branches. The 180degree  
phase shift is ensured in all situations (including transient  
phases) and whatever the operation mode is (CrM or  
DCM).  
Maximum Current Limit: the circuit permanently  
senses the input current for over current protection and  
inrush currents detection, for preventing the  
excessive stress suffered by the MOSFETs if they  
turned on when large inrush currents take place.  
Zero Current Detection: the NCP1632A prevents the  
MOSFET from closing until the inductor current is  
zero, to ensure discontinuous conduction mode  
operation in each branch.  
UnderVoltage Protection: the circuit turns off when  
it detects that the output voltage goes below 12% of the  
OVP level (typically). This feature protects the PFC  
stage from starting operation in case of too low ac line  
conditions or in case of a failure in the OVP monitoring  
network (e.g., bad connection).  
BrownOut Detection: the circuit detects too low ac  
line conditions and stop operating in this case. This  
protection protects the PFC stage from the excessive  
stress that could damage it in such conditions.  
Thermal Shutdown: an internal thermal circuitry  
disables the circuit gate drive and then keeps the power  
switch off when the junction temperature exceeds  
150°C typically. The circuit resumes operation once  
the temperature drops below about 100°C (50°C  
hysteresis).  
Frequency foldback and skipcycle capability for  
low power standby:  
The NCP1632A optimizes the efficiency of your PFC  
stage over the whole load range. In mediumand  
lightload conditions, the switching frequency can  
linearly decay as a function of the line current magnitude  
(FFOLD mode) down to about 30 kHz at very low power  
(depending on the OSC pin capacitor). To prevent any risk  
of regulation loss at no load and to further minimize the  
consumed power, the circuit skips cycles when the error  
amplifier output reaches its low clamp level.  
Fast Line / Load Transient Compensation:  
by essence, PFC stages are slow systems. Thus, the output  
voltage of PFC stages may exhibit excessive overand  
undershoots because of abrupt load or input voltage  
variations (e.g. at startup). The NCP1632A incorporates  
a fast line / load compensation to avoid such large output  
voltage variations. Practically, the circuit monitors the  
output voltage and:  
Interleaving  
An interleaved PFC converter consists of two paralleled  
PFC stages operated outofphase. Each individual stage is  
generally termed phase, channel or branch.  
If the input current is well balanced, each phase processes  
half the total power. The size and cost of each individual  
branch is hence accordingly minimized and losses are  
spitted between the two channels. Hence, hot spots are less  
likely to be encountered. Also, if the interleaving solution  
requires more components, they are smaller and often more  
standard. In addition, they can more easily fit applications  
with specific formfactors as required in thin flat panel TVs  
for instance.  
Furthermore, if the two channels are properly operated  
outofphase, a large part of the switchingfrequency ripple  
currents generated by each individual branch cancel when  
they add within the EMI filter and the bulk capacitors. As a  
result, EMI filtering is significantly eased and the bulk  
capacitor rms current is drastically reduced. Interleaving  
Disables the drive to stop delivering power as long as  
the output voltage exceeds the over voltage protection  
(OVP) level.  
Drastically speedsup the regulation loop (Dynamic  
Response Enhancer) when the output voltage is below  
95.5 % of its regulation level. This function is partly  
disabled during the startup phase to ensure a gradual  
increase of the power delivery (softstart).  
PFC OK: the circuit detects when the circuit is in normal  
situation or if on the contrary, it is in a startup or fault  
condition. In the first case, the pfcOK pin is in high state  
and low otherwise. The pfcOK pin serves to control the  
downstream converter operation in response to the PFC  
state.  
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8
NCP1632A  
therefore extends the CrM power range by sharing the task  
actually be extremely costeffective and efficient for  
powers above 300 watts. And even less for applications like  
LCD and Plasma TV applications where the need for smaller  
components, although more numerous, helps meet the  
required lowprofile formfactors.  
between the two phases and by allowing for a reduced input  
current ripple and a minimized bulk capacitor rms current.  
This is why this approach which at first glance, may  
appear more costly than the traditional 1phase solution can  
Branch 1  
IL1  
I
D 1  
Vin  
Iin  
Acline  
Branch 2  
IL 2  
I
D 2  
1
2
3
4
5
6
7
8
16  
15  
14  
13  
12  
11  
10  
9
I
line  
I
D(tot)  
V
cc  
Vout  
EMI  
Filter  
Cbulk  
Cin  
LOAD  
Rsense  
Figure 4. Interleaved PFC Stage  
The NCP1632A manages the 180degree phase shift  
between the two branches by modulating the oscillator  
swing as a function of the current cycle duration in the  
inductor of each individual phase. This onsemi proprietary  
technique ensures an accurate, stable and robust control of  
the delay between the two branches in all situations  
(including transient phases) and whatever the operation  
mode is (CrM or DCM).  
The ac line current is the averaged inductor current as the  
result of the EMI filter “polishing” action. Hence, the line  
current produced by one of the phase is:  
t1(t1 ) t2)  
2T L  
I
in + Vin  
(eq. 2)  
Where (T = t + t + t ) is the switching period and V is  
1
2
3
in  
the ac line rectified voltage.  
The NCP1632A is a voltage mode controller. As a result,  
the input current is optimally shared between the two  
branches if they have an inductor of same value. If the  
inductances differ, outofphase operation will not be  
affected. Simply, the branch embedding the lowestvalue  
inductor, will process more power as:  
Pbranch1 Lbranch2  
+
Pbranch2 Lbranch1  
(eq. 1)  
Figure 5. Current Cycle Within a Branch  
Inductor typical deviation being below 5%, the power  
between 2 branches should not differ from more than 10%.  
Provided its interleaving capability, the protections it  
features and the mediumto lightload efficiency  
enhancements it provides compared to traditional CrM  
circuits, the NCP1632A is more than recommendable for  
powers up to 600 W with universal mains and up to 1 kW in  
narrow mains applications.  
Equation 2 shows that the input current is proportional to  
t1ꢀ(t1 ) t2  
the input voltage if ǒ Ǔis a constant.  
T
This is what the NCP1632A does. Using the “Vton  
processing block” of Figure 5, the NCP1632A modulates t1  
t1ꢀ(t1 ) t2  
so that ǒ Ǔremains a constant:  
T
NCP1632A Ontime Modulation  
The NCP1632A incorporates an ontime modulation  
circuitry to support both the critical and discontinuous  
conduction modes. Figure 5 portrays the inductor current  
absorbed in one phase of the interleaved PFC stage. The  
initial inductor current of each switching cycle is always  
zero. The inductor current ramps up when the MOSFET is  
Ct @ VREGUL  
t1(t1 ) t2)  
+
T
It  
(eq. 3)  
Where C and I respectively, are the capacitor and charge  
t
t
current of the internal ramp used to control the ontime and  
is the signal derived from the regulation block  
V
REGUL  
which adjusts the ontime. This onsemi proprietary  
technique makes the NCP1632A able to support the  
Frequency Clamped Critical conduction mode of operation,  
that is, to operate in discontinuousor in criticalconduction  
mode according to the conditions, without degradation of  
on. The slope is (V /L) where L is the inductor value. At the  
IN  
end of the ontime (t ), the coil demagnetization phase  
1
starts. The current ramps down until it reaches zero. The  
duration of this phase is (t ). The system enters then the  
2
deadtime (t ) that lasts until the next clock is generated.  
3
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9
 
NCP1632A  
the power factor. Critical conduction mode is naturally  
Feedforward:  
obtained when the inductor current cycle is longer than the  
minimum period controlled by the oscillator. Discontinuous  
conduction mode is obtained in the opposite situation. In this  
case, the switching frequency is clamped.  
The C timing capacitors (one per phase) are internal and  
are well matched for an optimal current balancing between  
the two branches of the interleaved converter.  
t
As detailed in the brownout section, the I current is  
t
Hence, the averaged current absorbed by one of the phase  
of the PFC converter:  
internally processed to be proportional to the square of the  
voltage applied to the BO pin (pin 7). Since the BO pin is  
designed to receive a portion of the average input voltage,  
Ct @ VREGUL  
Vin  
2L  
I
in(phase1) + Iin(phase2)  
+
@
the I current is proportional to the square of the line  
t
It  
(eq. 4)  
magnitude which provides feedforward.  
In a typical application, the BO pin voltage is hence:  
Given the regulation low bandwidth of PFC systems,  
(V ) and then (V ) are slow varying signals.  
CONTROL  
REGUL  
Ǹ
2 2 Vin(rms)  
Rbo2  
bo1 ) Rbo2  
Hence, the line current absorbed by each phase is:  
Vpin7  
+
p
R
I
in(phase1) + Iin(phase2) + k @ Vin  
(eq. 9)  
(eq. 5)  
where R and R are the scaling down resistors for BO  
bo1  
bo2  
VREGULAR  
ƪ
ƫ
Where k is a constant k + Ct @  
@ L @ It .  
sensing (see brownout section)  
In addition, I is programmed by the pin 3 resistor so that  
2
t
Hence, the input current is then proportional to the input  
voltage and the ac line current is properly shaped.  
This analysis is valid for DCM but also CrM which is just  
the maximum ontime obtained when V  
is max  
REGUL  
(1.66 V) is given by:  
Rt2  
a particular case of this functioning where (t = 0). As a  
3
Ton,max (ms) ^ 50 @ 10*9  
@
2
result, the NCP1632A automatically adapts to the  
conditions and jumps from DCM and CrM (and vice versa)  
without power factor degradation and without discontinuity  
in the power delivery.  
Vpin7  
(eq. 10)  
From this, we can deduce the input current and power  
expressions:  
2
62 @ 10*14 @ Rt2  
L @ Vin(rms)  
The total current absorbed by the two phases is then:  
Rbo1  
@ ǒ1 ) Ǔ @  
Rbo2  
VREGUL  
VREGUL(max)  
Iin(rms)  
^
Ct @ V  
Iin(total)  
+
REGUL @ Vin  
L @ It  
(eq. 11)  
(eq. 6)  
2
Rbo1  
This leads to the following line rms current and average  
input power:  
62 @ 10*14 @ Rt2  
VREGUL  
VREGUL(max)  
@ ǒ1 ) Ǔ @  
Rbo2  
Pin(avg)  
^
L
Ct @ V  
Iin(rms)  
+
REGUL @ Vin(rms)  
(eq. 12)  
L @ It  
(eq. 7)  
(eq. 8)  
Ct @ V  
2
Pin(avg)  
+
REGUL @ Vin(rms)  
L @ It  
PWM  
comparator  
timing capacitor  
sawtooth  
+
to PWM latch  
Vton  
OA1  
V
REGUL  
+
SKIP  
R1  
OVP  
OFF  
S3  
C1  
OCP  
0.5*  
V
BOcomp  
(from BO block)  
(Isense  
210 m)  
IN1  
S1  
pfcOK  
S2  
> Vton during (t1+t2)  
Inrush  
DT  
(high during deadtime)  
> 0 V during t3 (deadtime)  
> Vton*(t1+t2)/T in average  
Figure 6. Vton Processing Circuit  
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10  
 
NCP1632A  
Regulation Block and Low Output Voltage Detection  
The swing of the error amplifier output is limited within  
an accurate range:  
A transconductance error amplifier with access to the  
inverting input and output is provided. It features a typical  
transconductance gain of 200 mS and a typical capability of  
20 mA. The output voltage of the PFC stage is typically  
scaled down by a resistors divider and monitored by the  
inverting input (feedback pin – pin2). The bias current is  
minimized (less than 500 nA) to allow the use of a high  
impedance feedback network. The output of the error  
amplifier is pinned out for external loop compensation  
(pin5). A type2 compensator is generally applied between  
pin5 and ground, to set the regulation bandwidth in the range  
of 20 Hz, as need in PFC applications (refer to application  
note AND8407).  
It is maintained above a lower value (V – 0.6 V typically)  
F
by the “low clamp” circuitry. When this circuitry is  
activated, the power demand is minimum and the  
NCP1632A enters skip mode (the controller stops  
pulsating) until the clamp is no more active.  
It is clamped not to exceed 3.0 V + the same V voltage  
F
drop.  
Hence, V  
features a 3 V voltage swing. V  
is then  
pin5  
pin5  
offset down by (V ) and divided by three before it connects  
F
to the “V  
processing block” and the PWM section.  
ton  
Finally, the output of the regulation is a signal (“V  
REGUL  
of the block diagram) that varies between 0 and 1.66 V.  
Dynamic Response Enhancer  
pfcOK  
Vout low  
150 mA  
detect  
50 mA  
VREGUL  
+
0.955*Vref  
1.66 V  
Error Amplifier  
FB  
20 mA  
+
Vref  
OFF  
Vcontrol  
+
V
F
+
4R  
VCONTROL  
V
F
V
REGUL  
3 V  
5R  
VF  
3 V +VF  
Figure 7. Regulation Block  
Figure 8. VREGUL versus VCONTROL  
Zero Current Detection  
Provided the low bandwidth of the regulation loop, sharp  
variations of the load, may result in excessive over and  
undershoots. Overshoots are limited by the OverVoltage  
Protection (see OVP section). A dynamic Response  
Enhancer circuitry (DRE) is embedded to contain the  
undershoots. Practically, an internal comparator monitors  
While the on time is constant, the core reset time varies  
with the instantaneous input voltage. The NCP1632A  
detects the demagnetization completion by sensing the  
inductor voltage. Sensing the voltage across the inductor  
allows an accurate zero current detection, more specifically,  
by detecting when the inductor voltage drops to zero.  
Monitoring the inductor voltage is not an economical  
solution. Instead, a smaller winding is taken off of the boost  
inductor. This winding (called the “zero current detection”  
or ZCD winding) gives a scaled version of the inductor  
voltage that is easily usable by the controller. Furthermore,  
this ZCD winding is coupled so that it exhibits a negative  
voltage during the MOSFET conduction time (flyback  
configuration) as portrayed by Figure 9.  
the feedback signal (V ) and connects a 200 mA current  
FB  
source to speedup the charge of the compensation network  
when VFB is lower than 95.5% of its nominal value. Finally,  
it is like if the comparator multiplied the error amplifier gain  
by about 10.  
One must note that a large part of the DRE current source  
(150mA out of 200 mA) cannot be enabled until the converter  
output voltage has reached its target level (that is when the  
“pfcOK” signal of the block diagram, is high). This is  
because, at the beginning of operation, it is generally  
welcome that the compensation network charges slowly and  
gradually for a soft startup.  
In that way, the ZCD voltage (“V  
”) falls and starts to  
AUX  
ring around zero volts when the inductor current drops to  
zero. The NCP1632A detects this falling edge and prevents  
any new current cycle until it is detected.  
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11  
NCP1632A  
Figure 9 shows how it is implemented.  
below zero (below the 0.25 V lower threshold of the ZCD  
comparator to be more specific). As a result, the ZCD  
For each phase, a ZCD comparator detects when the  
voltage of the ZCD winding exceeds its upper threshold (0.5  
V typically). When this is the case, the coil is in  
circuitry detects the V  
falling edge.  
AUX  
It is worth noting that as portrayed by Figure 10, V  
is  
AUX  
demagnetization phase and the latch L  
is set. This latch  
also representative of the MOSFET drainsource voltage  
ZCD  
is reset when the next driver pulse occurs. Hence the output  
of this latch (Q ) is high during the whole offtime  
(“V ”). More specifically, when V  
is minimal (below the input voltage V ). That is why V  
is below zero, V  
DS  
AUX DS  
ZCD  
IN  
ZCD  
(demagnetization time + any possible dead time). The  
output of the comparator is also inverted to form a signal  
is used to enable the driver so that the MOSFET turns on  
when its drainsource voltage is low. Valley switching  
reduces the losses and interference.  
which is AND’d with the Q  
output so that the AND gate  
ZCD  
output (V  
) turns high when the V  
voltage goes  
ZCD  
AUX  
Rzcd2  
Rzcd1  
D1  
1
ZCD1  
16  
ZCD2  
Vin  
L1  
AND1  
V
DMG1  
PWM  
latch  
PH1  
Vzcd1  
SET1  
+
Vcc  
Qzcd1  
S
Negative  
and  
positive  
clamp  
Negative  
and  
positive  
clamp  
DRV1  
Q
S
L
ZCD  
Q
Q
ZCD  
0.5 V  
CLK1  
(from phase  
management  
block)  
M1  
14  
R
R
output  
buffe r 1  
Inrush  
200ms  
delay  
reset signal  
(from PH1 PWM  
comparator)  
DT  
S
R
Q
Vout  
D2  
OFF  
L2  
Vin  
(from Fault  
management  
block)  
V
DMG2  
output  
PWM  
latch PH2  
Vzcd2  
SET2  
buffe r 2  
Vcc  
+
DRV2  
M2  
Qzcd2  
CLK2  
(from phase  
management  
block)  
S
S
R
Cbulk  
Q
Q
Cbulk  
11  
R
0.5 V  
Inrush  
reset signal  
(from PH2 PWM comparator)  
Figure 9. Zero Current Detection  
At startup or after an inactive period (because of a  
protection that has tripped for instance), there is no energy  
in the ZCD winding and therefore no voltage signal to  
activate the ZCD comparator. This means that the driver will  
never turn on. To avoid this, an internal watchdog timer is  
integrated into the controller. If the driver remains low for  
To prevent negative voltages on the ZCD pins (ZCD1 for  
phase 1 and ZCD2 for phase 2), these pins are internally  
clamped to about 0 V when the voltage applied by the  
corresponding ZCD winding is negative. Similarly, the ZCD  
pins are clamped to V  
(10 V typical), when the  
ZCD(high)  
ZCD voltage rises too high. Because of these clamps, a  
resistor (R and R of Figure 9) is necessary to limit  
more than 200 ms (typical), the timer sets the L  
latch as  
ZCD  
ZCD1  
ZCD2  
the current from the ZCD winding to the ZCD pin. The  
clamps are designed to respectively source and sink 5 mA.  
the ZCD winding signal would do. Obviously, this 200 ms  
delay acts as a minimum offtime if there is no  
demagnetization winding voltage is detected.  
It is hence recommended to dimension R  
and R  
to  
ZCD1  
ZCD2  
limit the ZCD1 and ZCD2 pins current below 5 mA.  
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12  
 
NCP1632A  
DRV  
time  
V
IN  
V
DS  
time  
time  
V
AUX  
CLOCK  
time  
Q
ZDC  
time  
time  
V
ZCD  
DT  
time  
Figure 10. Zero Current Detection Timing Diagram  
(VAUX is the Voltage Provided by the ZCD Winding)  
Current Sense  
The NCP1632A is designed to monitor a negative voltage  
proportional to the input current, i.e., the current drawn by  
Figure 11, a current sense resistor (R ) is practically  
inserted in the return path to generate a negative voltage  
CS  
the two interleaved branches (I ). As portrayed by  
(V ) proportional to I .  
CS in  
in  
VAUX2  
V
Iin  
in  
VOUT  
VAUX1  
L2  
D2  
EMI  
filter  
ICS  
OCP  
C
IN  
L1  
D1  
IILIM1  
Current  
Mirror  
M2  
DRV  
2
ICS  
Inrush  
ICS  
M1  
DRV  
1
Iinrush  
CBULK  
CS  
(QZCD1 and  
ZCD2 are  
from the  
QZCD 2  
QZCD 1  
9
Q
Negative clamp  
ICS  
DRV2  
ZCD block)  
DRV1  
ROCP  
RCS  
Iin  
Figure 11. Current Sense Block  
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13  
 
NCP1632A  
The NCP1632A uses V to detect when I exceeds its  
particularly if no inrush limiting circuitry is implemented.  
CS  
in  
maximum permissible level. To do so, as sketched by  
Figure 11, the circuit incorporates an operational amplifier  
that sources the current necessary to maintain the CS pin  
The power switches should not turn on during this severe  
transient. If not, they may be overstressed and finally  
damaged. That is why, the NCP1632A permanently  
monitors the input current and delays the MOSFET start of  
voltage near zero. By inserting a resistor R  
between the  
OCP  
CS pin and R , we adjust the current that is sourced by the  
switching until (I ) has vanished. This is the function of the  
CS  
in  
CS pin (I ) as follows:  
I
comparison to the I  
threshold (14 mA typical).  
CS  
CS  
inrush  
When I  
exceeds I  
, the comparator output  
CS  
inrush  
ǒ
Ǔ
ǒ
Ǔ
* RCS @ Iin ) ROCP @ ICS ^ 0  
(eq. 13)  
(“Inrush”) is high and prevents the PWM latches from  
setting (see block diagram). Hence, the two drivers (DRV1  
and DRV2) cannot turn high and the MOSFETs stay off.  
This is to guarantee that the MOSFETs remain open as long  
as if the input current exceeds 10% of the maximum current  
limit. Again, this feature protects the MOSFETs from the  
possible excessive stress it could suffer from if it was  
allowed to turn on while a huge current flowed through the  
coil as it can be the case at startup or during an overload  
transient.  
Which leads to:  
RCS  
ROCP  
ICS  
+
Iin  
(eq. 14)  
In other words, the CS pin sources a current (I ) which  
is proportional to the input current.  
Two functions use I : the over current protection and the  
inrush current detection.  
CS  
CS  
OverCurrent Protection (OCP)  
The propagation delay (I < I  
) to (drive outputs  
CS  
inrush  
If I exceeds I  
(210 mA typical), an overcurrent is  
CS  
ILIM1  
high) is in the range of few ms.  
detected and the ontime is decreased proportionally to the  
difference between the sensed current I and the 210 mA  
OCP threshold.  
The ontime reduction is done by injecting a current I  
in the negative input of the “V  
OPAMP. (See Figure 6)  
However when the circuit starts to operate, the  
NCP1632A disables this protection to avoid that the current  
produced by one phase and sensed by the circuit prevents the  
other branch from operating. Practically, some logic  
grounds the Inrush protection output when it detects the  
presence of “normal current cycles”. This logic simply  
consists of the OR combination of the Drive and  
demagnetization signals as sketched by Figure 11.  
in  
neg  
processing circuit”  
TON  
I
CS * IILIM1  
Ineg  
+
(eq. 15)  
2
This current is injected each time the OCP signal is high.  
OverVoltage Protection  
The maximum coil current is:  
While PFC circuits often use one single pin for both the  
OverVoltage Protection (OVP) and the feedback, the  
NCP1632A dedicates one specific pin for the undervoltage  
and overvoltage protections. The NCP1632A  
configuration allows the implementation of two separate  
feedback networks (see Figure 13):  
ROCP  
RCS  
Iin(max)  
+
IILIM1  
(eq. 16)  
Inrush Current Detection  
When the PFC stage is plugged to the mains, the bulk  
capacitor is abruptly charged to the line voltage. The charge  
current (named inrush current) can be extremely huge  
1. One for regulation applied to pin 2.  
2. Another one for the OVP function (pin 8).  
Vout (bulk voltage)  
Vout (bulk voltage)  
Rout1  
Rout1  
16  
15  
14  
13  
12  
11  
10  
9
1
2
16  
15  
14  
13  
12  
11  
10  
9
1
FB  
FB  
2
3
4
5
6
7
3
4
5
6
7
Rout3  
Rout2  
Rovp1  
Rovp2  
Rout2  
OVP  
OVP  
8
8
Figure 12. Configuration with One Feedback  
Figure 13. Configuration with Two  
Network for Both OVP and Regulation  
Separate Feedback Networks  
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14  
 
NCP1632A  
Oscillator Section – Phase Management  
The oscillator generates the clock signal that dictates the  
The double feedback configuration (Figure 13) offers  
some upgraded safety level as it protects the PFC stage  
even if there is a failure of one of the two feedback  
arrangements. In this case:  
maximum switching frequency (f ) of the interleaved PFC  
osc  
stage. In other words, each of the two interleaved branches  
cannot operate above half the oscillator frequency (f /2).  
osc  
The bulk regulation voltage (“V  
”) is:  
out(nom)  
The oscillator frequency (f ) is adjusted by the capacitor  
osc  
R
out1 ) R  
Rout2  
Vout(nom)  
+
out2 @ Vref  
applied to OSC pin (pin 4). Typically, a 220 pF capacitor  
approximately leads to a 260 kHz oscillator operating  
frequency, i.e., to a 130 kHz clamp frequency for each  
branch.  
As shown by Figure 14, a current source I (140 mA  
typically) charges the OSC pin capacitor until its voltage  
(eq. 17)  
The OVP level (“V ”) is:  
out(ovp)  
R
ovp1 ) Rovp2  
CH  
Vout(ovp)  
+
@ Vref  
Rovp2  
(eq. 18)  
exceeds V  
(5 V typically). At that moment, the  
OSC(high)  
Where V is the internal reference voltage (2.5 V typically)  
Now, if wished, one single feedback arrangement is  
possible as portrayed by Figure 12. The regulation and OVP  
ref  
oscillator enters a discharge phase for which I  
(105 mA  
DISCH  
typ.) discharges the OSC pin capacitor. This sequence lasts  
until V goes below the oscillator low threshold V  
OSC  
OSCL  
blocks having the same reference voltage (V ), the  
ref  
and a new charging phase starts*. An internal signal  
(“SYNC” of Figure 14) is high during the discharge phase.  
A divider by two uses the SYNC information to manage the  
phases of the interleaved PFC: the first SYNC pulse sets  
“phase 1”, the second one, “phase 2”, the third one phase 1  
againetc.  
According to the selected phase, SYNC sets the relevant  
“Clock generator latch” that will generate the clock signal  
(“CLK1” for phase 1, “CLK2” for phase 2) when SYNC  
drops to zero.  
resistance ratio R  
over R  
adjusts the OVP threshold.  
out2  
out3  
More specifically,  
The bulk regulation voltage (“V  
”) is:  
out(nom)  
R
out1 ) Rout2 ) R  
Vout(nom)  
+
out3 @ Vref  
R
out2 ) Rout3  
(eq. 19)  
(eq. 20)  
The OVP level (“V  
”) is:  
out(ovp)  
R
out1 ) Rout2 ) R  
Vout(ovp)  
+
out3 @ Vref  
Rout2  
Actually, the drivers cannot turn on at this very moment  
if the inductor demagnetization is not complete. In this case,  
the clock signal is maintained high and the discharge time is  
The ratio OVP level over regulation level is:  
Vout(ovp)  
Rout3  
Rout2  
+ 1 )  
prolonged although V  
is below V  
, until when the  
OSC  
OSCL  
Vout(nom)  
(eq. 21)  
core being reset, the drive pin turns high. The prolonged  
OSC discharge ensures a substantial 180degree phase shift  
in CrM, outofphase operation being in essence,  
guaranteed in DCM. In the two conditions (CrM or DCM),  
the interleaved operation is stable and robust.  
For instance, (V  
= 105% V ) leads to:  
out(nom)  
out(nom)  
(R  
out3  
= 5% R ).  
out2  
When the circuit detects that the output voltage exceeds  
the OVP level, it maintains the power switch open to stop the  
power delivery.  
*As detailed in the following sections, V  
is V  
OSCL  
OSC(low)  
4 V typically by default to set the frequency clamp level  
used in heavyload conditions. V is varied between 1  
OSCL  
and 3 V in FFOLD mode (frequency foldback mode) in  
response the FFOLD pin voltage.  
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15  
NCP1632A  
DRV1  
SYNCbar  
R
ICH  
CLK1  
Generation  
latch  
5 V  
SYNC  
CLK1  
OSC  
Q
S
S
COSC  
OSC  
latch  
Q_ph1  
SYNCbar  
Phase1  
Q
R
DRV2  
divider  
by two  
R
CLK2  
Generation  
latch  
CLK2  
Phase2  
Q
S
IDISCH  
Q_ph1  
SYNCbar  
4 V  
VOSCL  
ICS (from CS block)  
FFOLD mode  
Control  
of the  
oscillator  
low  
FFOLD  
1 V and 3 V  
clamps  
1 V  
3 V  
threshold  
( VOSCL  
)
HFC  
mode  
FFOLD  
mode  
+
4 V / 3 V  
Figure 14. FFOLD Mode Management  
If a capacitorC  
frequency is provided by:  
is applied to the OSC pin, the oscillator  
significant deadtime and prevent transitions between CrM  
and DCM within the input voltage sinusoid.  
OSC  
In Figure 15 a) configuration, a single oscillator sets a  
60 @ 10*6  
fosc  
^
C
OSC ) (10 @ 10*12  
)
frequency clamp. For instance, C  
= 220 pF forces  
OSC  
(eq. 22)  
120 kHz to be the maximum frequency within each branch  
(the FFOLD mode reduces this level in light load  
conditions). Such a clamp value is likely to force DCM  
operation in part of the input voltage sinusoid. To be able to  
force full CrM operation over a large working range, we  
And the switching frequency of each individual branch is  
clamped to the following f  
:
clamp  
30 @ 10*6  
fosc  
2
fclamp  
+
^
C
OSC ) (10 @ 10*12  
)
(eq. 23)  
would need to reduce C  
to a very low value (if not, the  
OSC  
clamp frequency can be lower than the switching one  
leading to DCM operation near the line zero crossing in  
particular). Still however, the oscillator must keep able to  
keep synchronized to the current cycle for proper  
outofphase control. This requires the oscillator swing to  
not to exceed its 1 V to 5 V range even in heavy load  
conditions when the switching frequency in each individual  
branch generally drops below 100 kHz. This is generally not  
possible with a single small capacitor on the OSC pin.  
Recommended Configuration  
As detailed above, the circuit automatically transitions  
between CrM and DCM depending on the current cycle  
duration being longer or shorter than the clamp frequency  
set by the oscillator. However, these transitions can lead to  
small discontinuities of the line current. To avoid them, the  
circuit should be operated in CrM without frequencyclamp  
interference when the line current is high and in deep DCM  
when it is below a programmed level. Deep DCM means that  
the switching frequency is low enough to ensure a  
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16  
 
NCP1632A  
OSC pin  
OSC pin  
OSC pin  
ROSC  
COSC  
ROSC  
(e.g., 5.1 kW)  
COSC  
(e.g., 82 pF)  
(e.g., 5.1 kW)  
(e.g., 68 pF)  
COSC  
(e.g., 220 pF)  
CFF  
(e.g., 270 pF)  
CFF  
(e.g., 330 pF)  
a) Basic configuration  
b) Option 1  
c) Option 2  
Figure 15. External Components Driving the OSC Pin  
Instead, the schematic of either Figure 15 b) or  
Figure 15 c) is to be used where:  
C sets the frequency in light load where the frequency  
FF  
foldback can force deep DCM operation (deep DCM  
means operation with a large deadtime to be far from the  
zone where the circuit can transition from CrM to DCM  
C  
(which value is much less than the second  
OSC  
capacitance C ) sets the highfrequency operation  
FF  
necessary for operating in CrM  
and vice versa). As previously mentioned, C also  
FF  
ensures that the oscillator voltage can stay above 1 V in  
deep CrM conditions.  
R  
limits the influence of the C capacitor as long as  
OSC  
FF  
the oscillator swing remains below (R  
.I  
) where  
OSC OSC  
I
is the charge or discharge current depending on the  
being limited by  
OSC  
Finally, Figure 15 b) and c) configurations provide some  
kind of variablecapacitance oscillator. For instance, Option  
b) provides the following typical characteristics:  
sequence. The voltage across C  
R
muchhighervalue capacitor (C ) is engaged when  
OSC  
(to about 1 V with 5.1 kW), the second  
OSC  
FF  
heavyload CrM operation imposes a larger oscillator  
swing.  
1
vramp  
1
vramp  
7.00  
5.00  
7.00  
5.00  
5 V  
5 V  
1
1
3 V  
4 V  
3.00  
3.00  
ms  
Tbranch ^3.3  
ms  
Tbranch ^13.6  
1.00  
1.00  
1.00  
1.00  
396u  
398u  
400u  
time in seconds  
402u  
404u  
392u  
396u  
400u  
time in seconds  
404u  
408u  
300 kHz frequency clamp in HFC  
mode (V > 4 V)  
73 kHz frequency clamp when entering  
FFOLD mode (V  
= 3 V)  
FFOLD  
FFOLD  
1
vramp  
7.00  
5.00  
5 V  
3.00  
1
1 V  
1.00  
ms  
Tbranch ^36  
1.00  
360u  
380u  
400u  
420u  
440u  
time in seconds  
28 kHz minimum frequency clamp (deepest  
DCM @ V = 1 V)  
FFOLD  
Figure 16. Clamp Frequency in Each Individual Branch with the Configuration of Figure 15 b)  
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17  
 
NCP1632A  
Figure 17 illustrates the oscillator operation at a low  
FFOLD voltage.  
3
IL1  
VDS1  
2
7
7.00  
VDS2  
IL2  
6
5
5 V  
5.00  
VOSC  
8
3.00  
9
1.00  
VFFOLD forces the OSC valley  
V
is in the range of 1.1 V  
FFOLD  
4
1.00  
FFOLD / HFC Flag (high in FFOLD mode)  
9.50m  
9.54m  
9.58m  
time in seconds  
9.62m  
9.66m  
Figure 17. Operation at a Low VFFOLD Value (VFFOLD = 1.1 V)  
HFC vs FFOLD Modes  
The transitions between the HFC and FFOLD modes and  
the frequency foldback characteristics are controlled by the  
FFOLD pin.  
The NCP1632A optimizes the PFC stage efficiency over  
the whole load range by entering the frequency foldback  
(FFOLD) mode when the line current magnitude is lower  
than a programmed level (see next section). More  
specifically, the circuit operates in:  
Frequency foldback (FFOLD) mode when the line  
current magnitude is lower than a programmed level. In  
this mode, the circuit frequency clamp level is reduced as  
a function of the FFOLD pin voltage in order to reduce the  
frequency in mediumand lightload operation. The  
frequency can decrease down to about 30 kHz at very low  
power (depending on the OSC pin capacitor)  
High frequency clamp (HFC) mode when the line current  
is high. In this mode, the clamp level of the switching  
frequency is set high so that the PFC stage mostly runs in  
critical conduction mode which is more efficient than the  
discontinuous conduction mode in heavy load conditions.  
Frequency Foldback (FFOLD) Management  
As detailed in the “current sense” section, the NCP1632A  
CS pin sources a current proportional to the input current  
(I of Figure 14). I is internally copied and sourced out  
CS  
CS  
of the FFOLD pin. This current is changed into a dc voltage  
by means of an external (R//C) network applied to the  
FFOLD pin. The obtained V  
voltage is proportional to  
FFOLD  
the line average current. As illustrated by Figure 18, the PFC  
stage enters the frequency foldback mode (FFOLD mode)  
when  
V
goes below 3.0 V, and recovers  
FFOLD  
highfrequency clamp mode (HFC mode) when the FFOLD  
voltage exceeds 4 V.  
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18  
 
NCP1632A  
V
V
OUT  
IN  
I
IN  
EMI  
Filter  
PFC Stage  
C
IN  
R
SENSE  
I
IN  
I
CS  
Current Mirror  
R
CS  
Lowpass filter to  
build a signal  
proportional to  
the average input  
current  
I
I
CS  
CS  
CS  
I
CS  
9
(ICS is  
proportional  
to the total  
input current)  
Negative clamp  
Oscillator low  
FFOLD  
6
threshold control  
HFC  
mode  
FFOLD  
mode  
+
4 V / 3 V  
Figure 18. Frequency Foldback Control  
In HFC mode, the oscillator lower threshold (V  
) is  
60% load at 270 V rms  
OSCL  
fixed and equal to V  
In FFOLD mode, V  
voltage as follows:  
(4 V typically).  
OSC(low)  
The PFC stage will recover HFC mode (V  
27% load at 90 V rms  
= 4 V) at:  
FFOLD  
is modulated by the FFOLD pin  
if V is between 1 and 3 V  
FFOLD  
OSCL  
81% load at 270 V rms  
V  
V  
V  
= V  
= 1 V if V  
= 3 V if V  
OSCL  
OSCL  
OSCL  
FFOLD  
Above values assume a ripplefree V  
voltage. The  
FFOLD  
is below 1 V  
exceeds 3 V  
FFOLD  
power thresholds for transition can be shift and the  
hysteresis reduced by the V ripple.  
At the transition between the two modes, the oscillator  
low threshold is 3 V. In the example of Figure 19, this leads  
the branch clamp frequency to be 73 kHz when entering and  
just before leaving the FFOLD mode.  
FFOLD  
FFOLD  
As an example, the FFOLD external resistor can be  
= 3 V) when the line current  
selected so that (V  
FFOLD  
threshold is equal to 20% of the maximum current.  
In a 90 to 270 V rms application, above criterion leads the  
PFC stage to enter FFOLD mode at:  
20% load at 90 V rms  
Figure 19 shows a “natural” transition FFOLD to HFC  
mode.  
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19  
NCP1632A  
7
6
VDS1  
IL1  
7.00  
IL2  
VDS2  
5
2
5 V  
3 V  
VOSC  
5.00  
4
1
3.00  
VFFOLD exceeds the 4 V threshold  
1.00  
DCM operation  
CrM operation  
1.00  
FFOLD / HFC Flag (high in FFOLD mode)  
3
8.44m  
8.48m  
8.52m  
8.56m  
8.60m  
time in seconds  
Figure 19. “Natural” Transition FFOLD to HFC Mode when VFFOLD exceeds 4 V  
HFCmode Recovery  
able to provide the full power. To solve this, the NCP1632A  
forces HFC operation whenever the DRE comparator trips*  
and remains in HFC mode until the output voltage recovers  
its regulation level (that is when OVLFlag1 of Figure 21  
turns low). At that moment, the conduction mode is  
normally selected as a function of the FFOLD pin voltage.  
See Figure 20.  
The FFOLD pin sources a current proportional to the input  
current. Placing a resistor and a capacitor between the  
FFOLD and GND pins, we obtain the voltage representative  
of the line current magnitude necessary to control the  
frequency foldback characteristics. The NCP1632A  
naturally leaves the FFOLD mode operation when the  
sensed input current being large enough, the FFOLD pin  
*The dynamic response enhancer (DRE) comparator trips  
when the output voltage drops below 95.5% of its  
regulation level.  
voltage (V  
) exceeds 4 V. Such a FFOLD to HFC  
FFOLD  
transition is shown by Figure 19.  
DRE  
Skip Mode of Operation  
The circuit enters skip mode when the regulation block  
HFC mode  
S
Q
Q
5
2
output (V  
) drops to its 0.6 V lower clamp level. At  
CONTROL  
very light load and low line conditions, ontimes can be  
short enough no to enter the lowconsumption skip mode.  
To prevent such an inefficient continuous operation from  
occurring, the NCP1632A forces a minimum ontime which  
corresponds to 10% the maximum ontime.  
R6  
100k  
R
OVLFlag1  
3
(high when V < V  
)
FB  
REF  
This does not mean that the PFC stage will enter skip  
mode when the load is less than 10% of the full load (or even  
much more considering the necessary headroom in the max  
Figure 20. Easing HFCmode Recovery  
Now, the FFOLD pin is heavily filtered and this time  
ontime setting when selecting R ). Since, the NCP1632A  
constant may cause long V  
settling phases. If while in  
t
FFOLD  
reduces the switching frequency in light load (FFOLD  
mode), this minimum ontime corresponds to much lower  
power levels, typically, in the range of 2% of the full power.  
very lightload conditions, the load abruptly rises, the  
FFOLD pin time constant may dramatically delay the  
HFCmode recovery. As a result, during the FFOLD mode  
of operation, the PFC stage may run in DCM and may not be  
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20  
 
NCP1632A  
Excessive die temperature detected by the thermal  
shutdown.  
UnderVoltage Protection (“UVP” high)  
Brownout situation (“BONOK” high)  
Latchingoff of the circuit by an external signal  
applied to pin 10 and exceeding 2.5 V (“STDWN” of  
the block diagram turns high).  
Low Clamp  
Too low the current sourced by the R pin (“R  
”)  
t(open)  
t
During the PFC stage startup, that is, until the output  
voltage reaches its regulation level. The startup phase is  
detected by the latch “L ” of the block diagram.  
STUP  
“L ” is in high state when the circuit enters or recovers  
STUP  
Figure 21. VCONTROL Low Clamp  
operation after one of above major faults and resets when  
the error amplifier stops charging its output capacitor, that  
is, when the output voltage of the PFC stage has reached  
its desired regulation level. At that moment, “STUP” falls  
down to indicate the end of the startup phase.  
The circuit consumption is minimized (below 1 mA) for  
a skipping period of time.  
PfcOK / REF5V Signal  
The NCP1632A can communicate with the downstream  
converter. The signal “pfcOK/REF5V” is high (5 V) when  
the PFC stage is in nominal operation and low otherwise.  
More specifically, “pfcOK/REF5V” is low:  
Finally, “pfcOK/REF5V” is high when the PFC output  
voltage is properly and safely regulated. “pfcOK/REF5V”  
should be used to allow operation of the downstream  
converter.  
Whenever a major fault condition is detected which turns  
off the circuit, i.e.:  
BrownOut Protection  
The brownout pin is designed to receive a portion of the  
Incorrect feeding of the circuit (“UVLO” high). The  
UVLO signal turns high when V  
drops below  
CC  
input voltage (V ). As V is a rectified sinusoid, a capacitor  
IN  
IN  
V
(10 V typically) and remains high until V  
CC(OFF)  
CC  
must be applied to the BO pin so that V is proportional to  
BO  
exceeds V  
(12 V typically).  
CC(ON)  
the average value of V .  
IN  
FeedForward  
Circuitry  
Current Mirror  
Rt  
I
BO  
Vbo (BO pin voltage)  
Rt  
Vbo  
IBO2 charges the timing  
I
BO  
V
in  
capacitorforbothphases of  
the interleaved PFC  
Ac line  
BOCOMP  
EMI  
Filter  
R
R
Vbo  
VBOCOMP (high when VBO < 1 V)  
bo1  
bo2  
1 V  
BO  
BO_NOK  
C
in  
T
S
delay  
2
S
C
bo  
R
cs  
50ms  
50ms  
delay  
L
Q
BO  
delay  
R
Vdd  
980 mV  
reset  
reset  
reset  
7 mA  
This PNP transistor maintains  
the BO pin below the BO  
threshold when the circuit is  
not fed enough to control the  
state of the BO block  
Circuitry for  
S
1
brownout  
detection  
Figure 22. Brownout Block  
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21  
 
NCP1632A  
The BO pin voltage is used by two functions (refer to  
Figure 22):  
The line lower threshold is:  
R
bo1 ) R  
Rbo2  
p
(Vin,rms  
)
+
@
bo2 @ VBO(th)  
boL  
Feedforward. Generation of an internal current  
Ǹ
2 2  
proportional to the input voltage average value (I ). V  
Rt  
BO  
Hence the ratio upper over lower  
is:  
@ǒ1 )  
thǓreshold  
is buffered and made available on the R pin (pin 3).  
t
(Vin,rms  
)
R
bo1 @ Rbo2 @ IBO  
2
p
Hence, placing a resistor between pin 3 and ground,  
enables to adjust a current proportional to the average  
boH  
boL  
+
(Vin,rms  
)
(Rbo1 ) Rbo2 @ VBO(th)  
input voltage. This current (I ) is internally copied and  
As in general R  
is large compared to R , the  
Rt  
bo1  
bo2  
squared to form the charge current for the internal timing  
capacitor of each phase. Since this current is proportional  
to the square of the line magnitude, the conduction time  
is made inversely proportional to the line magnitude. This  
feedforward feature makes the transfer function and the  
power delivery independent of the ac line level. Only the  
precedent equation can simplify as follows:  
(Vin,rms  
)
R
bo2 @ IBO  
2
boH  
boL  
@ǒ1 ) Ǔ  
^
p
VBO(th)  
(Vin,rms  
)
Details of Operation of the Circuitry for Brownout  
Detection  
regulation output (V  
) controls the power amount.  
In nominal operation, the voltage applied to pin 7 must be  
higher than the 1 V internal voltage reference. In this case,  
REGUL  
Note that if the I current is too low (below 7 mA  
Rt  
the output of the comparator BOCOMP (V  
) is  
typically), the controller goes in OFF mode to avoid  
damaging the MOSFETs with too long conduction time.  
BOCOMP  
low (see Figure 22). Conversely, if V goes below 1 V,  
BO  
V
turns high and a 980 mV voltage source is  
In particular, this addresses the case when the R pin is  
BOCOMP  
t
connected to the BO pin to maintain the pin level near 1 V.  
The high state of V is used to detect a brownout  
condition. However, the brownout detection is not  
open.  
BOCOMP  
Brownout protection. A 7 mA current source lowers the  
BO pin voltage when a brownout condition is detected.  
This is for hysteresis purpose as required by this function.  
In traditional applications, the monitored voltage can be  
very different depending on the phase:  
immediate. First, as soon as a high level occurs, this  
information is stored by a latch (L of Figure 22) and a  
BO  
50 ms delay is activated. No BO fault can be detected until  
this time has elapsed. The main goal of the 50 ms lag is to  
help meet the holdup requirements. In case of a short mains  
interruption, no fault is detected and hence, the “pfcOK”  
signal remains high and does not disable the downstream  
converter. In addition, the BO pin voltage being kept at  
980 mV, there is almost no extra delay between the line  
Before operation, the PFC stage is off and the input  
bridge acts as a peak detector (refer to Figure 23). As  
a consequence, the input voltage is approximately flat  
and nearly equates the ac line amplitude:  
Ǹ
vinꢀ(t) + 2 @ Vin,rms, where V  
is the rms voltage  
in,rms  
of the line. Hence, the voltage applied to the BO pin  
Rbo2  
(pin 7) is: VBO + 2 @ Vin,rms  
recovery and the occurrence of the steady state V voltage,  
BO  
Ǹ
which otherwise would exist because of the large capacitor  
typically placed between pin7 and ground to filter the input  
voltage ripple. As a result, the NCP1632A effectively  
“blanks” any mains interruption that is shorter than 38 ms  
(minimum guaranteed value of the 50 ms timer).  
At the end of this 50 ms blanking delay, another timer is  
activated that sets a 50 ms window during which a fault can  
be detected. This is the role of the second 50 ms timer of  
Figure 22:  
If the output of OPAMP is high at the end of the first delay  
(50 ms blanking time) and before the second 50 ms delay  
time is elapsed, a brownout fault is detected (BO_NOK  
is high).  
@
.
R
bo1 ) Rbo2  
After the PFC stage has started operation, the input  
voltage becomes a rectified sinusoid and the voltage  
Ǹ
2 2 @ Vin,rms  
Rbo2  
applied to pin7 is: VBO  
+
@
,
p
R
bo1 ) Rbo2  
i.e., about 64% of the previous value. Therefore, the  
same line magnitude leads to a V voltage which is  
36% lower when the PFC is working than when it is  
off. That is why a large hysteresis (in the range of 50%  
of the upper threshold) is required.  
BO  
Other applications may require a different hysteresis  
amount. That is why the hysteresis is made programmable  
and dependent on the internal 7 mA current source. More  
specifically, reusing the components of Figure 22:  
If the output of OPAMP remains low for the duration of  
the second delay, no fault is detected.  
The  
line  
upper  
BO  
threshold  
is:  
In any case, the L latch and the two delays are reset at  
the end of the second delay.  
When the “BO_NOK” signal is high, the driver is  
BO  
R
bo1 ) Rbo2  
Rbo2  
R
bo1 @ Rbo2 @ IBO  
1
ǒ
Ǔ
(Vin,rms  
)
+
@
VBO(th) )  
boH  
Ǹ
R
bo1 ) Rbo2  
2
disabled, the “V ” pin is grounded to recover operation  
control  
where V  
is the BO comparator threshold (1 V  
BO(th)  
with a softstart when the fault has gone and the “pfcOK”  
typically) and I , the 7 mA current source.  
BO  
www.onsemi.com  
22  
NCP1632A  
voltage turns low to disable the downstream converter. In  
addition, both 50 ms timers are reset, the 980 mV clamp is  
removed (S is off) and I , the 7 mA current source, is  
enabled to lower the pin7 voltage for hysteresis purpose (as  
explained above).  
to guarantee that the circuit starts operation in the right state,  
that is, “BONOK” high. When V exceedsV , the pnp  
transistor turns off and the circuit enables the 7 mA current  
source. The 7 mA current source remains on until the BO pin  
voltage exceeds the 1 V BO threshold.  
CC  
CC(on)  
2
BO  
A pnp transistor ensures that the BO pin voltage remains  
below the 1 V threshold until V reaches V  
. This is  
CC  
CC(on)  
Figure 23. Typical Input Voltage of a PFC Stage  
Output Drive Section  
Thermal Shutdown (TSD)  
An internal thermal circuitry disables the circuit gate drive  
and then keeps the power switch off when the junction  
temperature exceeds 140°C typically. The output stage is  
then enabled once the temperature drops below about 80°C  
(60°C hysteresis).  
The circuit embeds two drivers to control the two  
interleaved branches. Each output stage contains a totem  
pole optimized to minimize the cross conduction current  
during high frequency operation. The gate drive is kept in a  
sinking mode whenever the UnderVoltage Lockout  
(UVLO) is active or more generally whenever the circuit is  
off. Its high current capability (500 mA/+800 mA) allows  
it to effectively drive high gate charge power MOSFET.  
The temperature shutdown keeps active as long as the  
circuit is not reset, that is, as long as V keeps higher than  
CC  
V
. The reset action forces the TSD threshold to be  
CC(reset)  
the upper one (140°C). This ensures that any cold startup  
will be done with the right TSD level.  
Reference Section  
The circuit features an accurate internal reference voltage  
(V ). V  
is optimized to be 2.4% accurate over the  
UnderVoltage Lockout Section  
REF  
REF  
The NCP1632A incorporates an UnderVoltage Lockout  
block to prevent the circuit from operating when the power  
supply is not high enough to ensure a proper operation. An  
temperature range (the typical value is 2.5 V). V  
voltage reference used for the regulation and the  
overvoltage protection. The circuit also incorporates a  
is the  
REF  
UVLO comparator monitors the pin 12 voltage (V ) to  
precise current reference (I  
)
that allows the  
CC  
REF  
allow the NCP1632A operation when V exceeds 12 V  
OverCurrent Limitation to feature a 6% accuracy over  
CC  
typically. The comparator incorporates some hysteresis  
the temperature range.  
(2.0 V typically) to prevent erratic operation as the V  
CC  
Fault Mode  
The following block details the function.  
crosses the threshold. When V goes below the UVLO  
CC  
comparator lower threshold, the circuit turns off.  
The circuit off state consumption is very low: < 50 mA.  
This low consumption enables to use resistors to charge  
the V capacitor during the startup without the penalty of  
CC  
a too high dissipation.  
www.onsemi.com  
23  
NCP1632A  
Internal  
Thermal  
Shutdown  
Vref  
Vcc  
VDD  
Regul  
TSD  
Iref  
Stdwn  
UVP  
Vcc_OK  
BO_NOK  
Rt(open)  
UVLO  
+
12 V / 10 V  
Q
R
S
30ms  
blanking  
time  
IRt_Low  
(Ipin3 < 7 mA)  
OFF  
Fault  
management  
Figure 24. Fault Management Block  
The circuit detects a fault if the R pin is open. Practically,  
UnderVoltage Protection (“UVP”)  
Latchoff condition (“Stdwn”)  
Die overtemperature (“TSD”)  
t
if the pin sources less than 7 mA, the “I ” signal sets a  
Rt_Low  
latch that turns off the circuit if its output (R ) is high.  
t(open)  
A 30 ms blanking time avoids parasitic fault detections. The  
Too low the current sourced by the R pin (“R  
”)  
t(open)  
t
latch is reset when the circuit is in UVLO state (too low V  
levels for proper operation).  
CC  
“UVLO” (improper Vcc level for operation)  
When any of the following faults is detected:  
brownout (“BO_NOK”)  
The circuit turns off. It recovers operation when the fault  
disappears.  
www.onsemi.com  
24  
MECHANICAL CASE OUTLINE  
PACKAGE DIMENSIONS  
SOIC16  
CASE 751B05  
ISSUE K  
DATE 29 DEC 2006  
SCALE 1:1  
NOTES:  
1. DIMENSIONING AND TOLERANCING PER ANSI  
Y14.5M, 1982.  
A−  
2. CONTROLLING DIMENSION: MILLIMETER.  
3. DIMENSIONS A AND B DO NOT INCLUDE MOLD  
PROTRUSION.  
4. MAXIMUM MOLD PROTRUSION 0.15 (0.006) PER SIDE.  
5. DIMENSION D DOES NOT INCLUDE DAMBAR  
PROTRUSION. ALLOWABLE DAMBAR PROTRUSION  
SHALL BE 0.127 (0.005) TOTAL IN EXCESS OF THE D  
DIMENSION AT MAXIMUM MATERIAL CONDITION.  
16  
9
8
B−  
P 8 PL  
M
S
B
0.25 (0.010)  
1
MILLIMETERS  
INCHES  
MIN  
0.386  
DIM MIN  
MAX  
MAX  
0.393  
0.157  
0.068  
0.019  
0.049  
A
B
C
D
F
9.80  
3.80  
1.35  
0.35  
0.40  
10.00  
G
4.00 0.150  
1.75 0.054  
0.49 0.014  
1.25 0.016  
F
R X 45  
K
_
G
J
1.27 BSC  
0.050 BSC  
0.19  
0.10  
0
0.25 0.008  
0.25 0.004  
0.009  
0.009  
7
K
M
P
R
C
7
0
_
_
_
_
T−  
SEATING  
PLANE  
5.80  
0.25  
6.20 0.229  
0.50 0.010  
0.244  
0.019  
J
M
D
16 PL  
M
S
S
A
0.25 (0.010)  
T B  
STYLE 1:  
STYLE 2:  
STYLE 3:  
STYLE 4:  
PIN 1. COLLECTOR  
2. BASE  
3. EMITTER  
4. NO CONNECTION  
5. EMITTER  
6. BASE  
7. COLLECTOR  
8. COLLECTOR  
9. BASE  
10. EMITTER  
11. NO CONNECTION  
12. EMITTER  
13. BASE  
PIN 1. CATHODE  
2. ANODE  
3. NO CONNECTION  
4. CATHODE  
5. CATHODE  
6. NO CONNECTION  
7. ANODE  
8. CATHODE  
9. CATHODE  
10. ANODE  
11. NO CONNECTION  
12. CATHODE  
13. CATHODE  
14. NO CONNECTION  
15. ANODE  
PIN 1. COLLECTOR, DYE #1  
2. BASE, #1  
3. EMITTER, #1  
4. COLLECTOR, #1  
5. COLLECTOR, #2  
6. BASE, #2  
PIN 1. COLLECTOR, DYE #1  
2. COLLECTOR, #1  
3. COLLECTOR, #2  
4. COLLECTOR, #2  
5. COLLECTOR, #3  
6. COLLECTOR, #3  
7. COLLECTOR, #4  
8. COLLECTOR, #4  
9. BASE, #4  
10. EMITTER, #4  
11. BASE, #3  
12. EMITTER, #3  
13. BASE, #2  
7. EMITTER, #2  
8. COLLECTOR, #2  
9. COLLECTOR, #3  
10. BASE, #3  
11. EMITTER, #3  
12. COLLECTOR, #3  
13. COLLECTOR, #4  
14. BASE, #4  
SOLDERING FOOTPRINT  
14. COLLECTOR  
15. EMITTER  
16. COLLECTOR  
14. EMITTER, #2  
15. BASE, #1  
16. EMITTER, #1  
15. EMITTER, #4  
16. COLLECTOR, #4  
8X  
6.40  
16. CATHODE  
16X  
1.12  
STYLE 5:  
STYLE 6:  
STYLE 7:  
PIN 1. SOURCE N‐CH  
PIN 1. DRAIN, DYE #1  
2. DRAIN, #1  
3. DRAIN, #2  
4. DRAIN, #2  
5. DRAIN, #3  
6. DRAIN, #3  
7. DRAIN, #4  
8. DRAIN, #4  
9. GATE, #4  
PIN 1. CATHODE  
2. CATHODE  
3. CATHODE  
4. CATHODE  
5. CATHODE  
6. CATHODE  
7. CATHODE  
8. CATHODE  
9. ANODE  
2. COMMON DRAIN (OUTPUT)  
3. COMMON DRAIN (OUTPUT)  
4. GATE P‐CH  
5. COMMON DRAIN (OUTPUT)  
6. COMMON DRAIN (OUTPUT)  
7. COMMON DRAIN (OUTPUT)  
8. SOURCE P‐CH  
1
16  
16X  
0.58  
9. SOURCE P‐CH  
10. SOURCE, #4  
11. GATE, #3  
12. SOURCE, #3  
13. GATE, #2  
14. SOURCE, #2  
15. GATE, #1  
16. SOURCE, #1  
10. ANODE  
11. ANODE  
12. ANODE  
13. ANODE  
14. ANODE  
15. ANODE  
16. ANODE  
10. COMMON DRAIN (OUTPUT)  
11. COMMON DRAIN (OUTPUT)  
12. COMMON DRAIN (OUTPUT)  
13. GATE N‐CH  
14. COMMON DRAIN (OUTPUT)  
15. COMMON DRAIN (OUTPUT)  
16. SOURCE N‐CH  
1.27  
PITCH  
8
9
DIMENSIONS: MILLIMETERS  
Electronic versions are uncontrolled except when accessed directly from the Document Repository.  
Printed versions are uncontrolled except when stamped “CONTROLLED COPY” in red.  
DOCUMENT NUMBER:  
DESCRIPTION:  
98ASB42566B  
SOIC16  
PAGE 1 OF 1  
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