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.