The FAN604H is an advanced PWM controller aimed at achieving power density of ≥10W/in3 in universal input range AC/DC flyback isolated power supplies. It incorporates Quasi-Resonant (QR) control with proprietary Valley Switching with a limited frequency variation. QR switching provides high efficiency by reducing switching losses while Valley Switching with a limited frequency variation bounds the frequency band to overcome the inherent limitation of QR switching. FAN604H features mWSaver® burst mode operation with extremely low operating current (300 μA) and significantly reduces standby power consumption to meet the most stringent efficiency regulations such as Energy Star’s 5-Star Level and CoC Tier II specifications.FAN604H includes several user configurable features aimed at optimizing efficiency, EMI and protections. FAN604H has a wide blanking frequency range that improves light load efficiency and eliminating audio noise for adaptive application. It incorporates user-configurable constant current reference, which allows controlling the maximum output current from primary-side, thereby optimizing transformer design to improve the overall efficiency. It also includes several rich programmable protection features such as over-voltage protection (OVP), precise constant output current regulation (CC).