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The SD8666QS is a quasi-resonant current mode PWM+PFM controller with built-in high voltage power MOSFET, and external sensing resistor, is applicable to SMPS applications.

The SD8666QS features multi-mode control., At heavy load condition. it operates in QR mode to reduce switch loss in the high line input voltage, and it operates with fixed frequency (65KHz) in CCM mode in the low line input voltage. At medium load or light load conditions, it works in QR+PFM mode to improve the conversion efficiency. At no load condition, it enters burst mode to reduce the standby power dissipation.

The SD8666QS has frequency jitter function for low EMI. The available peak current compensation function ensures the limit output power consistency even with different AC input voltages. The soft startup reduces the device stress during power-on process.

The SD8666QS integrates comprehensive protections including VCC overvoltage protection, output over-load protection, output overvoltage protection, leading edge blanking, cycle-by-cycle peak current limit, short circuit protection for output diode, AC input voltage undervoltage protection and over temperature protection, etc.

Main feature

QR mode for low EMI and low switch loss

PFM mode at light load condition for higher conversion efficiency

Entering burst mode at no load condition

Frequency rising at low voltage and heavy load condition for high limit output power

Frequency jitter for low EMI

Peak current compensation

Soft startup 

VCC overvoltage protection

Output overload protection

Leading edge blanking

Cycle-by-cycle current limit

Output diode short protection

Undervoltage protection for AC input voltage

Adjustable output overvoltage protection

Over temperature protection

Ordering Information
Product Name Package form Marking Hazardous Substance Control Packing Type Remarks
SD8666QS EHSOP-5-325-1.7 SD8666QS Halogen free Tube
SD8666QSTR EHSOP-5-325-1.7 SD8666QS Halogen free Tape&Reel
Block Diagram

SD866QS 英文.png

title Types of Size (KB) date Download the latest English version
SD8666QS PDF 122 2020-10-23 SD8666QS Datasheet