An isolated flyback controller with single stage active power factor correction (PFC) has been developed by Linear Technology Corporation. The device has a power factor of more than 0.97, which is enabled by actively modulating the input current, which takes away the need for an extra switching power stage and associated components.

In addition, no opto-isolator or signal transformer is required for feedback since the output voltage is sensed from the primary-side flyback signal.

The controller complies with the IEC61000-3-2 Harmonic Current Emissions specification. Efficiencies greater than 86 percent can be achieved with output power levels up to 100W.

The device’s input voltage range is dependent on the choice of external components and it can operate over a 90VAC to 277VAC range. The LT3798 can be designed into high input voltage DC applications, making it suitable for industrial, EV/EHV automotive, mining and medical applications.