onsemi NCP1937A2DR2G

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.

• Wide VCC 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) Load
• 0.5 A / 0.8 A Source / Sink Gate Drivers
• Internal Temperature Shutdown Power
• Power Savings Mode Reduces Supply Current Consumption to 70 μA Enabling Very Low Input Power Applications
• Feed−Forward for Improved Operation across Line and stable PFC Disable Threshold Based on Output
• 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
• 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