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© Semiconductor Components Industries, LLC, 2013
November, 2013 − Rev. 3
1 Publication Order Number:
NCP1937/D
NCP1937
Combination Power Factor
Correction and Quasi-
Resonant Flyback
Controllers for Adapters
This combination IC integrates power factor correction (PFC) and
quasi−resonant flyback functionality necessary to implement a
compact and highly efficient Switched Mode Power Supply for an
adapter application.
The PFC stage exhibits near−unity power factor while operating in a
Critical Conduction Mode (CrM) with a maximum frequency clamp.
The circuit incorporates all the features necessary for building a robust
and compact PFC stage while minimizing the number of external
components.
The quasi−resonant current−mode flyback stage features a
proprietary valley−lockout circuitry, ensuring stable valley switching.
This system works down to the 4
th
valley and toggles to a frequency
foldback mode with a minimum frequency clamp beyond the 4
th
valley to eliminate audible noise. Skip mode operation allows
excellent efficiency in light load conditions while consuming very low
standby power consumption.
Common General Features
• Wide V
CC
Range from 9 V to 30 V with Built−in Overvoltage
Protection
• High−Voltage Startup Circuit and Active Input Filter Capacitor
Discharge Circuitry for Reduced Standby Power
• Integrated High−Voltage Brown−Out Detector
• Integrated High−Voltage Switch Disconnects PFC Feedback Resistor
Divider to Reduce Standby Power
• Fault Input for Severe Fault Conditions, NTC
Compatible (Latch and Auto−Recovery Options)
• 0.5 A / 0.8 A Source / Sink Gate Drivers
• Internal Temperature Shutdown
• Power Savings Mode Reduces Supply Current
Consumption to 70 mA Enabling Very Low Input Power
Applications
PFC Controller Features
• Critical Conduction Mode with Constant On Time
Control (Voltage Mode) and Maximum Frequency
Clamp
• Accurate Overvoltage Protection
• Bi−Level Line−Dependent Output Voltage
• Fast Line / Load Transient Compensation
• Boost Diode Short−Circuit Protection
• Feed−Forward for Improved Operation across Line and
Load
• Adjustable PFC Disable Threshold Based on Output
Power
QR Flyback Controller Features
• Valley Switching Operation with Valley−Lockout for
Noise−Free Operation
• Frequency Foldback with Minimum Frequency Clamp
for Highest Performance in Standby Mode
• Minimum Frequency Clamp Eliminates Audible Noise
• Timer−Based Overload Protection (Latched or
Auto−Recovery options)
• Adjustable Overpower Protection
• Winding and Output Diode Short−Circuit Protection
• 4 ms Soft−Start Timer
http://onsemi.com
SOIC−20
Narrow Body
CASE 751BS
MARKING DIAGRAM
HV/X2
BO/X2
QFB
PControl
PONOFF
QCT
Fault
PSTimer
PFBHV
PFBLV
GND
PCS/PZCD
PDRV
QDRV
QCS
NCP1937 = Specific Device Code
xx = A1, A2, A3, B1, B2, B3, C1, C4 or C61
A = Assembly Location
WL = Wafer Lot
YY = Year
WW = Work Week
G = Pb−Free Package
120
NCP1937xxG
AWLYWW
VCC
QZCD
See detailed ordering and shipping information on page 5 of
this data sheet.
ORDERING INFORMATION
Verzeichnis
- ・ Abmessungen des Paketumrisses on Seite 37
- ・ Paket-Footprint-Pad-Layout on Seite 37
- ・ Teilenummerierungssystem on Seite 1 Seite 37
- ・ Markierungsinformationen on Seite 1 Seite 37
- ・ Blockdiagramm on Seite 3 Seite 18 Seite 19 Seite 22 Seite 26
- ・ Typisches Anwendungsschaltbild on Seite 2
- ・ Beschreibung der Funktionen on Seite 4
- ・ Anwendungsbereich on Seite 1
- ・ Elektrische Spezifikation on Seite 7 Seite 8 Seite 9 Seite 10 Seite 11
