• Secondary Side Regulation
• Integrated 800V Power MOSFET
• HV Start-Up
• 100kHz Switching Frequency
• Pseudo-Fixed Frequency Control to Eliminate Slope Compensation for CCM (Duty Cycle>50%)
• PFM Control for High Average Efficiency
• Burst Mode Control for High Light Load Efficiency
• 23.5kHz Minimum Switching Frequency to Eliminate Audible Noise
• Frequency Modulation to Reduce EMI Noise
• Internal Soft-Start Process
• Programmable Input BO/OVP Through PRT Pin
• OLP, VCC OVP, OTP, Secondary Diode SCP
• Compact Package: DIP7

The SY50428 is an SSR (Secondary Side Regulation) flyback converter featuring PWM/PFM (Pulse Width Modulation/Pulse Frequency Modulation) operating mode and a 100kHz rated switching frequency. It integrates a 800V power MOSFET within a DIP7 package. HV (High Voltage) start up is integrated on DRAIN pin to minimize load loss. It uses a pseudo-fixed frequency control strategy to avoid sub-harmonic oscillation under CCM (Continuous Conduction Mode). SY50428 enters frequency fold-back mode when the load decreases to achieve a high average efficiency. Under light load conditions, it enters burst mode for high efficiency. The device uses switching frequency modulation function to reduce EMI (Electro-Magnetic Interference) noise, and features a soft-start process to reduce current on the power MOSFET during Vin start up.

The SY50428 provides reliable protections including programmable input BO (Brown Out) / OVP (Over Voltage Protection), VCC OVP, OLP (Over Load Protection), OTP (Over Temperature Protection), and secondary diode SCP (Short Circuit Protection).

The SY50428 is available in a compact DIP7 package.