Onsemi NCP1937

Description

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 aCritical Conduction Mode (CrM) with a maximum frequency clamp.The circuit incorporates all the features necessary for building a robustand compact PFC stage while minimizing the number of externalcomponents. The quasi−resonant current−mode flyback stage features aproprietary valley−lockout circuitry, ensuring stable valley switching.This system works down to the 4th valley and toggles to a frequencyfoldback 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

• Wide VCC Range from 9 V to 30 V with Built−in OvervoltageProtection
• High−Voltage Startup Circuit and Active Input Filter CapacitorDischarge Circuitry for Reduced Standby Power
• Integrated High−Voltage Brown−Out Detector
• Integrated High−Voltage Switch Disconnects PFC Feedback ResistorDivider to Reduce Standby Power
• Fault Input for Severe Fault Conditions, NTCCompatible (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 A Enabling Very Low Input PowerApplications PFC Controller Features
• Critical Conduction Mode with Constant On Time
• Control (Voltage Mode) and Maximum FrequencyClamp
• 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 Clampfor 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

More information

• Datasheet
• IC product information