L6566 Flyback Converter Controller - STMicroelectronics

STMicroelectronics introduced the new L6566 Flyback Converter Controller,  targeted to  applications such as TV and LCD monitors, small size LCD TVs, AC/DC adapters and high end chargers.

L6566 Flyback Converter Controller - Block Diagram

Key features of L6566 Flyback Converter Controller:

• Selectable multi mode operation: fixed frequency or qusi resonant
• Advance light load management
• On board 700 V high voltage start up
• <3mA quiescent current
• Adaptive UVLO
• -600/+800mA totem pole gate driver with active pull down during UVLO
• Line feedforward for constant power capability vs  mains voltage
• Tansformer saturation detection
• Pulse by pulse OCP, shutdown on overload
• Switched supply rail for PFC controller
• Brownout protection

The new Flyback Converter Controller features an externally programmable oscillator which defines the converter’s switching frequency in FF mode and the maximum allowed switching frequency in QR mode. When FF operation is selected, the IC works like a standard current-mode controller (UC384x-like) with a maximum duty cycle limited at 70 % min. QR operation, when selected, occurs at heavy load and is achieved through a transformer demagnetization sensing input that triggers the Power MOSFET’s turn-on.

With a very small load, in FF or QR operation the IC enters controlled burst-mode operation that, along with the built-in non-dissipative high-voltage start-up circuit and a reduced quiescent current, helps keep the consumption from the mains low while meeting the most demanding energy saving regulations.

Using the L6566 Flyback Converter Controller, instead of a traditional PWM saves about 25Wh per day assuming 6 hours operation at full load, while the reduced standby consumption (220mW compared to the 500mW allowed by the Environmental Protection Agency (EPA) Code of Conduct saves another 5Wh per day. Yearly energy savings in an LCD TV are 9.6kWh assuming the TV is in use for 320 per year. Assuming 70M units produced and a 25% market share, this gives an annual energy saving of 170GWh. A similar calculation for AC/DC Adapters (280 days use, 50M units and 25% market share) gives an annual energy saving of 115GWh. These two applications alone can save the equivalent of 10% of the output of a medium-size (3000GWh/year) power station, which also saves about 300,000 metric tons of CO2 emissions.

L6566 Flyback Converter Controller is supplied in two versions:

• L6566A is specifically designed for offline flyback converters operating from a front-end Power Factor Corrector. The L6566A provides an interface with the PFC controller that turns-off the pre-regulator at light load.
• L6566B is designed for offline flyback converters where a front-end PFC is not expected. L6566B has a frequency modulation input that modulates the oscillator frequency. This modulation is used to reduce the peak value of EMI emission.

The L6566 Flyback Converter Controller  is available in an SO-16 package, priced at $0.50 in quantities of 2500 pieces.

More info: L6566 Flyback Converter Controller - STMicroelectronics