The SY50296/8A is a high frequency quasi-resonant (QR) flyback converter designed for Power Delivery (PD) adaptors and quick chargers. It integrated GaN FET in a small package and suitable for wide output voltage range applications. Switching frequency can be 25kHz–500kHz and transformer size can be smaller.
The SY50296/8A operates using peak current control. It provides a QR mode in which the GAN FET can be turned on at a valley point to reduce switching loss, especially under high input voltages.
In conventional QR flyback solutions, the valley number always varies between 1 and 2 or 3 and 5, which increases VO ripple and creates audible noise. The SY50296/8A uses a proprietary circuit to lock the valley number between 1 and 6, for improved stability compared with other conventional QR solutions.
If load decreases, SY50296/8A will enter discontinuous conduction mode (DCM) to reduce the switching frequency for higher efficiency. If the load is very light, the SY50296/8A will enter burst mode to reduce power loss.
The SY50296/8A provides comprehensive functions to ensure reliable operation, including: HV startup, X-cap discharge, brown-out protection, output and VCC overvoltage protection (OVP), output undervoltage protection (UVP), internal over temperature protection (OTP), and open-loop protection (OLP).
It is recommended to use SY5239 as secondary side Synchronous Rectifier (SR) controller and Zero Voltage Switching (ZVS) can be achieved for higher efficiency.
The SY50296/8A is available in a QFN5*7-18 package.
