STMicroelectronics | EVL6566B-65W-QR

Both fixed-frequency (FF) and quasi-resonant (QR) operation are supported. The user can pick either of the two depending on application needs. 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 % min. 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. Under some conditions, ZVS (zero-voltage switching) can be achieved. Converter’s power capability rise with the mains voltage is compensated by line voltage feed forward. At medium and light load, as the QR operating frequency equals the oscillator frequency, a function (valley skipping) is activated to prevent further frequency rise and keep the operation as close to ZVS as possible.

Features:

• Selectable multi-mode operation: fixed frequency or quasi-resonant
• On-board 700 V high-voltage start-up
• Advanced light load management
• Low quiescent current (< 3 mA)
• Adaptive UVLO
• Line feed forward for constant power capability vs mains voltage
• Pulse-by-pulse OCP, shutdown on overload
• Transformer saturation detection
• Programmable frequency modulation for EMI reduction
• Latched or autorestart OVP
• Brownout protection
• -600/+800 mA totem pole gate driver with active pull-down during UVLO
• SO-16N package

Applications:

• Hi-end AC-DC adapter/charger
• LCD TV/monitor, PDP
• digital consumer, IT equipment
• single-stage PFC