NCP1937: Combination Power Factor Correction & Quasi-Resonant Flyback Controller

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 4th valley and toggles to a frequency foldback mode with a minimum frequency clamp beyond the 4th valley to eliminate audible noise. Skip mode operation allows excellent efficiency in light load conditions while consuming very low standby power consumption.

Features
  • <10mW No Load Standby Performance
  • High Voltage Startup Circuit and Active Input Filter Capacitor Discharge Circuitry
  • High Voltage Line Voltage Detector
  • Integrated High Voltage Switch Disconnects PFC Feedback Resistor Divider
  • Fault Input for Severe Fault Conditions
  • Bi-Level Line-Dependent Output Voltage
  • Boost Diode Short-Circuit Protection
  • Adjustable PFC Disable Threshold Based on Output Power
  • Frequency Foldback with Minimum Frequency Clamp
  • Minimum Frequency Clamp
  • Valley Switching Operation with Valley-Lockout
  • PFC
  • QR Flyback Controller
Benefits
  • Lowest no load performance
  • Eliminates the need for an external HV startup circuit and X2 resistors.
  • Optimize performance based on 110 v or 220 V ac mains
  • Reduces no load standby power
  • Enhanced protection capability
  • Optimized system with different input voltages
  • Enhanced protection features
  • Optimized system to improve efficiency
  • Enhanced efficiency at light and no load
  • Eliminates audible noise
  • Noise free operation
Applications
  • Adapters
  • Combo PFC+QR
End Products
  • All-In-One (AIO) Computers
  • High Power Notebook Adapters
Design & Development Tools (1)
Document TitleDocument ID/SizeRevisionRevision Date
NCP1937 Design WorksheetNCP1937 DWS.XLS (183.0kB)0
Data Sheets (1)
Document TitleDocument ID/SizeRevisionRevision Date
Combo PFC & QR Flyback ControllerNCP1937/D (964kB)4Jun, 2015
Evaluation Board Documents (4)
Document TitleDocument ID/SizeRevisionRevision Date
NCP1937BADAPGEVB Bill of Materials ROHS CompliantNCP1937BADAPGEVB_BOM_ROHS.PDF (290kB)2
NCP1937BADAPGEVB Gerber Layout Files (Zip Format)NCP1937BADAPGEVB_GERBERS.ZIP (135kB)2
NCP1937BADAPGEVB SchematicNCP1937BADAPGEVB_SCHEMATIC.PDF (366kB)2
NCP1937BADAPGEVB Test ProcedureNCP1937BADAPGEVB_TEST_PROCEDURE.PDF (156.0kB)0
Package Drawings (1)
Document TitleDocument ID/SizeRevision
SOIC20 NB LESS PINS 2, 4 & 19751BS (65.1kB)O
Evaluation/Development Tool Information
ProductStatusComplianceShort Description
NCP1937BADAPGEVBActivePb-free90 W Adapter PFC+QR 10 MW Evaluation Board
Order Information
ProductStatusCompliancePackageMSL*ContainerBudgetary Price/Unit
NCP1937A1DR2GActivePb-free Halide freeSOIC-20 NB751BS1Tape and Reel2500$0.6
NCP1937A2DR2GActivePb-free Halide freeSOIC-20 NB751BS1Tape and Reel2500$0.6
NCP1937A3DR2GActivePb-free Halide freeSOIC-20 NB751BS1Tape and Reel2500$0.6
NCP1937B1DR2GActivePb-free Halide freeSOIC-20 NB751BS1Tape and Reel2500$0.6
NCP1937B2DR2GActivePb-free Halide freeSOIC-20 NB751BS1Tape and Reel2500$0.6
NCP1937B3DR2GActivePb-free Halide freeSOIC-20 NB751BS1Tape and Reel2500$0.6
NCP1937C1DR2GActivePb-free Halide freeSOIC-20 NB751BS1Tape and Reel2500$0.6
NCP1937C4DR2GActivePb-free Halide freeSOIC-20 NB751BS1Tape and Reel2500$0.6
NCP1937C61DR2GActivePb-free Halide freeSOIC-20 NB751BS1Tape and Reel2500$0.6
Specifications
ProductPFC ModeFrequency OperationControl ModeTopologyfSW Typ (kHz)VCC Max (V)Drive Cap. (mA)UVLO (V)LatchUVPInhibition
NCP1937A1DR2GCRMVariableCurrent ModeFlybackVariable300.5YesYesYesYes
NCP1937A2DR2GCRMVariableCurrent ModeFlybackVariable300.5Yes
NCP1937A3DR2GCRMVariableCurrent ModeFlybackVariable300.5Yes
NCP1937B1DR2GCRMVariableCurrent ModeFlybackVariable300.5YesYesYesYes
NCP1937B2DR2GCRMVariableCurrent ModeFlybackVariable300.5Yes
NCP1937B3DR2GCRMVariableCurrent ModeFlybackVariable300.5Yes
NCP1937C1DR2GCRMVariableCurrent ModeFlybackVariable300.5YesYesYesYes
NCP1937C4DR2GCRMVariableCurrent ModeFlybackVariable300.5Yes
NCP1937C61DR2GCRMVariableCurrent ModeFlybackVariable300.5Yes
Combo PFC & QR Flyback Controller (964kB) NCP1937
NCP1937 Design Worksheet NCP1937
NCP1937BADAPGEVB BOM ROHS NCP1937BADAPGEVB
NCP1937BADAPGEVB GERBERS NCP1937BADAPGEVB
NCP1937BADAPGEVB SCHEMATIC NCP1937BADAPGEVB
NCP1937BADAPGEVB TEST PROCEDURE NCP1937BADAPGEVB
SOIC20 NB LESS PINS 2, 4 & 19 NCP1937