• Integrated 100V HV Start-up circuit
• Flexible Topology：

• Primary-Side Regulated (PSR) Flyback (250kHz/400kHz Selectable)
• Secondary-Side Regulated (SSR) Flyback (Programmable Frequency)

• Precision Voltage Reference  Output Diode Compensation in PSR Mode
• Source/Sink=0.5A/0.9A GATE Drivers  Programmable Soft-start
• Programmable Line Under Voltage Lockout (UVLO) with Adjustable Hysteresis
• External Programmable Thermal Shutdown
• OLP compensation for wide-input range
• Cycle-by-Cycle Current Sense Limit
• Frequency Modulation for EMI reduction
• Hiccup Protection for OLP, SCP, OVP and Thermal Shutdown 

The SY5609 is a fully-featured PWM controller integrated high voltage start-up circuit that operates over a wide input range up to 100V.

The SY5609 adopts current mode, quasi constantfrequency control to avoid sub-harmonic oscillation with no need of slope compensation. The SY5609 is specifically designed for both low cost, small size, high efficiency isolated solution with primary-side regulates (PSR) Flyback and Secondary-side regulates (SSR) Flyback application. Additional features include precision reference, output diode Compensation compensation (in PSR), over-voltage protection (in PSR) , line undervoltage lockout, cycle by cycle current limit, frequency modulation, soft-start, external programmable thermal shutdown and internal OTP.

The SY5609 is available in a QFN 4X4-20L package.