• PF>0.95, THD<5%
• Boost Quasi Resonant (QR) Operation
• Boost Burst Operation at Light Load
• LLC Fast Dynamic Response
• LLC Integrated Half Bridge Driver
• Input BO/BI Protection
• HV OVP Protection
• Boost Output, LLC Output OVP Protection
• Cycle by Cycle Peak Current Protection
• Over Temperature Protection
• LLC Capacitive Mode Protection

The SY5955A is a PFC+LLC combo controller that integrates a Boost PFC controller and a resonant halfbridge controller. The Boost converter operates in CrM/DCM mode to minimize switching losses and enhance EMI performance. A proprietary control method is utilized to achieve unity power factor (PF) and the lowest total harmonic distortion (THD). The burst function increases efficiency at low Load conditions. Reliable input brownout/brown-in protection, Boost output over-voltage protection (OVP) and under-voltage protection (UVP), over-current protection, and Boost feedback protection ensure safe operation. The LLC converter with proprietary control achieves a fast dynamic response and simplifies the design of loop compensation parameters. The number of peripheral devices is significantly reduced, resulting in lower BOM costs. The SY5955A also features output over-voltage protection (OVP), over-temperature protection (OTP), and over-load protection (OLP) for safe operation.