• Suitable for CCM, DCM and QR Mode Flyback Converters
• DSEN Pin Sensing up to 200V
• DSEN Falling Slope Rate Detection to Avoid False Turn on of SR MOSFET by Parasitic Ring
• Uses DSEN High Voltage Blanking Time to Enhance System ESD Performance
• GATE Pin Clamped Before VDD on
• Dual Supply Channel for 3.3V to 21V Output Systems
• Up to 500kHz Switching Frequency
• 10 ns Typical Turn off Propagation Delay
• 2A Sink, 0.5A Source Gate Driver Capability
• Compact Package: SOT23-6

The SY5231A is a synchronous rectification controller with high performance capabilities, ideal for use in flyback converters operating in CCM (Continuous Conduction), DCM (Discontinuous Conduction), and QR (Quasi-Resonant) modes.

It can drive both standard and logic-level N-channel MOSFETs for secondary-side synchronous rectification.

To prevent false turn-on by parasitic ringing under DCM or QR mode, the device uses the DSEN voltage falling slope rate detection.

The SY5231A features a DSEN high-voltage blanking time detection function that enhances system ESD performance, preventing external noise from false turnon of the SR (Synchronous Rectifier) MOSFET.

Under CCM operating mode, it has an extremely short turn-off delay time, while the DSEN voltage regulation fully utilizes the conduction time of the SR MOSFET for optimizing the efficiency under DCM and QR modes.

During light load conditions, the controller enters power saving mode to improve light load efficiency.