The L6566B is an extremely versatile current-mode primary Pulse Width Modulation (PWM) Controller specifically designed for high-performance offline flyback converters. It is also suited for single-stage single-switch input-current-shaping converters (single-stage PFC) for applications supposed to comply with EN61000-3-2 or JEITA-MITI regulations. Both fixed-frequency (FF) and quasi-resonant (QR) operation are supported. The device features an externally programmable oscillator, it defines converter's switching frequency in FF mode and the maximum allowed switching frequency in QR mode. When FF operation is selected, the ICs work like a standard current-mode controller with a maximum duty cycle limited at 70% minimum. The oscillator frequency can be modulated to mitigate EMI emissions. QR operation, when selected, occurs at heavy load and is achieved through a transformer demagnetization sensing input that triggers MOSFET's turn-on.
Feature
- Selectable multi-mode operation - fixed frequency or quasi-resonant
- Advanced light load management
- Low quiescent current (<3mA)
- Adaptive UVLO
- Line feedforward for constant power capability vs mains voltage
- Pulse-by-pulse OCP, shutdown on overload (latched or autorestart)
- Transformer saturation detection
- Programmable frequency modulation for EMI reduction
- Latched or autorestart OVP
- Brownout protection
