The UCC3888 controller is optimized for use with off-line, low-power, low-voltage, regulated bias supplies. Unique circuit topology, this device can be seen as two cascaded flyback converters, each in continuous operation mode, driven by a single external power switch. The significant advantages of this method are the ability to achieve high voltage slew rates of up to 400 V, transformerless and low internal losses of 2.7 V.
The control algorithm adopts the UCC3888 to set the time inversely proportional input line voltage switch, and set the shutdown time to be inversely proportional, output voltage switch. This action is referenced by an internal automatic feedback control loop and reference