Universal Input AC/DC Switching Buck Regulator – 85V -265V AC Input – 5V/150mA DC Output

The project presented here is a universal input AC/DC switching buck regulator with ultra-low standby power that is capable of delivering up to 2.5W output power. The RAA223012 chip is the heart of the project which combines constant off-time control for heavy load and Pulse Frequency Modulation (PFM) for light-load operation. Constant off-time controls switching frequency above the audible frequency of approximately 50kHz. PFM eliminates any potential audible noises while offering superior light-load efficiency and ultra-low power consumption (<10mW at no load). Efficiency is achieved up to 75%. The built-in frequency dithering further reduces the EMI noise spectrum.  The RAA223012 also features input brownout protection that prevents input circuitry from the overcurrent at low input voltage, and hiccup protections for output fault conditions such as short-circuit, overload, and open feedback.