NCP1937_V01中文資料安森美半導(dǎo)體數(shù)據(jù)手冊PDF規(guī)格書

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.

Common General Features

? 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)

? 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 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