FAN7621B: PFM Controller for Half-Bridge Resonant Converter

The FAN7621B is a pulse frequency modulation controller for high-efficiency half-bridge resonant converters.Offering everything necessary to build a reliable and robust resonant converter, the FAN7621B simplifies designs and improves productivity, while improving performance. The FAN7621B includes a highside gate-drive circuit, an accurate current controlled oscillator, frequency limit circuit, soft-start, and built-in protection functions. The high-side gate-drive circuit has a common-mode noise cancellation capability, which guarantees stable operation with excellent noise immunity. Using the zero-voltage-switching (ZVS) technique dramatically reduces the switching losses and efficiency is significantly improved. The ZVS also reduces the switching noise noticeably, which allows a small-sized Electromagnetic Interference (EMI) filter. The FAN7621B can be applied to various resonant converter topologies; such as series resonant, parallel resonant, and LLC resonant converters.

Features

• Variable Frequency Control with 50% Duty Cycle for Half-bridge Resonant Converter Topology
• High Efficiency through Zero Voltage Switching (ZVS)
• Fixed Dead Time (350ns)
• Up to 300kHz Operating Frequency
• Pulse Skipping for Frequency Limit (Programmable) at Light-Load Condition
• Remote On/Off Control using CON Pin
• Protection Functions: Over-Voltage Protection (OVP), Overload Protection (OLP), Over-Current Protection (OCP), Abnormal Over-Current Protection (AOCP), Internal Thermal Shutdown (TSD)

Application Notes