The maximum power handling capability is determined by both circuit operation and thermal condition. For a given output voltage, the maximum power increases with input voltage before triggering the thermal protection. An over-power-protection (OPP) is implemented to limit maximum output power and reduces power stage RMS current at high input voltage. The OPP is implemented by a feed-forward control from the input voltage to the OPP burst duty cycle (D_OPP). The D_OPP adds a "baby" burst within the on-time of "Mama" burst from the main feedback loop for the (VDD-VEE) regulation. When the input voltage increases, the D_OPP reduces automatically to limit the averaged output power.

At high ambient temperature, the thermal performance determines the maximum power and safe operating area (SOA). A protective thermal shut-down is triggered after overtemperature is detected. The high-efficiency and optimized thermal design for transformer and silicon provide a high power handling capability at high ambient temperature in a small package.

Figure 8-4 Diagram of Over-Power-Protection with baby burst