Isolated Flyback Converter with 18V-28V Input and 12V Output

The project presented here is a micropower no-opto isolated flyback converter featuring the LT8304 chip from Analog Devices. This circuit outputs 12V and maintains tight regulation with a load current from 10mA up to 1A and over an input voltage from 18V to 28V. The project needs less than 0.5% of its full output power as a minimum load to maintain good output voltage regulation. The transformer leakage inductance causes a voltage spike on the primary side after the power switch turns off. To limit this leakage inductance spike within the MOSFET voltage rating of 150V, an RC snubber, and a TVS clamp are installed to dampen the ringing and clamp the MOSFET drain voltage to a safe level.